Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

Engineering science >> Nuclear physics
141 proposition(s).

Additive manufacturing of a high temperature strain jauge

DLORR (CTReg)

Autre DLORR

01-10-2020

SL-DRT-20-0217

manuel.fendler@cea.fr

(.pdf)

The Internet of Things brings intelligence and connectivity within industrial tools. It gathers a real-time knowledge of the equipment parameters, which allows optimizing the processes by a better control and monitoring of the manufacturing conditions. The accumulation of data allows statistical processing by machine learning to improve the process and control in real time thanks to more connectivity and embedded intelligence. At the heart of data collection in the tools, many sensors are designed based on a common sensing element: the strain gauge. However, the operating conditions in the industrial environment are extremely severe; the major degradation stimulus is temperature, with values commonly exceeding 400 ° C, eliminating the use of gauges that are performed exclusively on plastic substrates. The aim of this thesis is to develop high temperature gauge sensors, leveraging additive techniques for both the fabrication and integration of gauges on topologically optimized test bodies.

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Contactless electronics under high-temperature and radiation exposures

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Intégration Gestion d'Energie Capteurs et Actionneurs

SL-DRT-20-0249

gael.pillonnet@cea.fr

(.pdf)

The objective is to design a new generation of contactless electronics to be robust to high-temperature and radiation expositions. Based on the recently introduced ?contactless electronics? paradigm, the PhD student have to define new mechanical structures and electronics schemes to operate in harsh conditions and to offer analog- and digital-operations. This study is based on a complete breakthrough proposal compared to the classical transistor-based electronics to overcome the inherent physical limit of transistor at high-temperature. The PhD student will propose, model and simulate electro-mechanical micro fabricated structures to validate the theoretical principle recently announced by some senior-scientists in our laboratory. The project involves multi-disciplinary study including microelectronics, electromechanical MEMS devices, solid-state physics and gives an excellent opportunity for PhD student to cover a large scientific scope.

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AI processing of time series for smart sensors

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Infrastructure et Ateliers Logiciels pour Puces

01-10-2020

SL-DRT-20-0261

marielle.malfante@cea.fr

(.pdf)

Today, sensors are used to acquire data of a given modality (acoustics, pressure, image, etc.). Usually, such data are stored before being analysed, for instance with machine learning methods. The relevant information is thereby extracted. A large variety of sensors and use cases can be considered: ? Microphones for the automatic classification of acoustic landscapes, ? Pressure sensors to study deformation and monitor various architectures (brides, dams, wind turbines, etc.), ? Seismometers to detect signals warning of a seisms or of a volcanic eruption, ? Smart watches or bracelets to detect stress phases, ? Etc. The issue of smart sensors consists in creating and designing sensors whose output is the relevant information, straightaway (see Fig. 1). Most of the time the raw signal no longer has to be transferred and stored. Smart sensors are a challenge in numerous fields, typically when sensors have to run autonomously in remote environments, or with limited power and storage access. For instance when studying acoustic landscapes pour environmental monitoring (forest, underwater areas, etc). IoT and wearable sensors are also targeted. Turning a sensor into a smart sensor presents a challenge at many levels. For instance, efficient AI methods to process the data need to be designed, with constraints in term of computation power and energy. Another challenge consists in building those analysis tools from small datasets, or from weakly supervised datasets. CEA is already conducting researches on those issues, and AI based methods are particularly relevant. This PhD subjects focuses on sensors recording time series: IMU, microphones, connected bracelets, etc. The core of the issue is to work on AI methods for time series, in one or several applicative fields. The PhD registers in a larger subject, namely AI reliability (anomaly detection, detection of events of class unseen during the training stage, etc.), but also the development of AI methods under labelling constraint. The topic is ambitious and several approaches are considered.

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Realization by additive manufacturing of a 3D ceramic / metal device, applied to remote power transfer and to remote control.

DMIPY (CTReg)

Autre DMIPY

01-09-2020

SL-DRT-20-0282

regis.delsol@cea.fr

(.pdf)

CEA Tech's materials platform focuses on the shaping of advanced ceramics and offers R&D partnerships in additive manufacturing involving ceramics parts. The proposed thesis aims the increase of the knowledge and expertise needed to design and realize ceramic / metal devices. The chosen application is the remote control and the remote power transfer of a mechatronic system consisting of one or several sensors. The first phase of the thesis of a duration of 9 months will consist in a bibliography study and a dimensioning study in order to choose the best ceramic / metal couple with respect to the application case. The second phase of a duration of 9 months will consist in additive manufacturing and metallization of planar prototypes and will consist in mechanical, morphological and dielectric characterization. The third phase of a duration of 12 months will lead to additive manufacturing and metallization of the final 3D prototype. Eventually, the performance of the prototype will be evaluated though functional testing.

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Integration of piezoelectric-based power converters

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Intégration Gestion d'Energie Capteurs et Actionneurs

SL-DRT-20-0286

adrien.morel@cea.fr

(.pdf)

The aim of this thesis is to integrate high-efficiency power converters based on resonating piezoelectric transducers. A large part of the work is to develop the integrated circuit to handle high switching frequency operation while maintaining an adiabatic energy transfer. Based on our recently published results [Pollet2019], the integration of the power stage and the control between phases paves the way of the miniaturization of the piezoelectric transducer using microelectronics process. The PhD student will cover the sizing, IC design, electro-mechanical characterization and feedback control of miniaturized piezoelectric-based power converters. [Pollet2019] B. Pollet et al., A New Non-Isolated Low-Power Inductorless Piezoelectric DC?DC Converter, Trans. on Power Electronics, 2019.

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Embedded AI for the semantic interpretation of a probabilistic environment model

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Infrastructure et Ateliers Logiciels pour Puces

01-10-2020

SL-DRT-20-0291

tiana.rakotovao@cea.fr

(.pdf)

The perception and modelling of an environment is a major issue when developing autonomous vehicles. How to model the surroundings of a vehicle? How to detect and identify the various obstacles? What about free spaces, and areas safe to drive on? Which sensor combination is the most appropriate to reach an exhaustive description and modelling of the environment? Those questions all have beginnings of answers, but still remain open and not yet solved. There also is a strong constraint regarding the need for embedding systems, which is one of the CEA focuses. Which processing and analysis can be considered while targeting embedded systems? Occupancy Grid is a model used to represent the surroundings of a vehicle and present various advantages. Several sensors of various modalities are used to compute the grid: each modality brings a specific information. For instance, infra-red is efficient by night, LIDAR offers a 360° field of view but is not robust to bad weather conditions, in which case a radar would be preferable. Ultrasound sensors on the contrary are used to analyse very short distances. CEA has developed approaches based on Bayesian fusion to produce SigmaFusion library. SigmaFusion is a tool to fuse the information of different sensors to produce an occupancy grid, which evolves with time. A strong point of SigmaFusion is the computing optimization: the technology is particularly efficient and competitive under strong embedded constraints (low cost integration with low energy consumption on micro-controller certified for critical task for the automotive market). An issue currently addressed is the use of EdgeAI methods to gain a semantic interpretation of an occupancy grid. A typical question is the level of knowledge and interpretation that can be reached while respecting the embedding constraint. Is it possible to detect the object evolving in a grid automatically, in real time and at low energetic cost (pedestrians, cyclists, cars, etc.)?

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Electrochemical deposition of insulating polymer films

Département des Plateformes Technologiques (LETI)

Laboratoire

01-10-2020

SL-DRT-20-0308

paul.haumesser@cea.fr

(.pdf)

The electrohoretic deposition is a well known technique to form polymeric coatings with a variety of materials such as polyetherimide (PEI). This technique usually requires the application of several (tens of) volts. Under such conditions, electrochemical reactions occur at the electrodes, such as solvent decomposition, that promote polymer precipitation at their surface. Recent results suggest that these electrochemical reactions are sufficiently active at much lower overpotentials (below 3V). This would enable deposition processes under mild conditions with improved control over the film properties. In this thesis, the mechanisms at play during the deposition of PEI under such mild conditions will be studied, with the aim of developing a process suitable for the fabrication of capacitors with high breakdown voltage. This approach will also be extended to other insulating polymers compatible with healthcare applications (such as packaging of wiring circuits for implant systems) or to hydrophilic and/or porous polymers for the encapsulation of biologic structures (cells, enzymes, bacteria) or cell filtration in biochips.

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Characterization of all-solid-state batteries using neutron and synchrotron facilities

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Matériaux

01-10-2019

SL-DRT-20-0317

lionel.picard@cea.fr

(.pdf)

In view to increasing both energy density and safety of lithium batteries, all solid state battery systems are currently of interest, either based on the use of polymer or inorganic electrolyte materials, or the combination of them as hybrid electrolytes. Research activities in this field are already well established at CEA-Grenoble, such as the developments of ionic conductive ceramic materials and single-ion conductive polymers. In this frame, the PhD student will aim at supporting this work through better understanding of the hybrid electrolyte system. The objectives of the PhD student will be the in depth characterisation of the structure and properties of such systems, including local/nanoscale organisation, organic-inorganic interfaces and electrolyte-electrode interfaces. The studies will use materials already available at CEA and novel cathodes from UMICORE, as well as new material under development. The student will employ cutting-edge neutron and synchrotron techniques, such as small angle scattering, tomography, micro-beam and imaging techniques, to characterise the hybrid materials both ex situ and operando in devices and propose potential optimisation to the systems.

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Development of high-performance NdFeB permanent magnet using Powder Injection Moulding

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Formulation des Matériaux

01-11-2020

SL-DRT-20-0329

sebastien.rolere@cea.fr

(.pdf)

Due to their remarkable magnetic properties, permanent magnets made of NdFeB alloys are an important part of the Energy Transition, with several applications in Energy (wind turbines) and in Transport (electric vehicle) sectors, for example. NdFeB magnets are usually produced by powder compression and sintering, and complex shapes are obtained through expensive machining operations. The powder injection moulding (PIM) process allows the direct production of parts with complex geometries through the conventional plastics processing technics, and is a way to reduce both machining operations and waste materials. Therefore, PIM is currently under consideration for the manufacturing of permanent NdFeB magnets with high density and magnetic performances and complex geometries. Nevertheless, the use of organic polymer binders for injection moulding (i), and the post-injection chemical and physical debinding steps (ii) during the PIM procedure, can be responsible of potential organic (i.e. carbon and/or oxygen) contaminations of the NdFeB powder, and consequently, of a significant degradation of magnetic properties of the magnets. Each of these contributions needs to be in-depth studied, for optimizing the magnetic properties of injection-moulded permanent NdFeB magnets. In particular, the understanding of the physicochemical interactions between polymer binders (and/or their degradation products) with the NdFeB powders, should lead to the development of feedstocks compatible with the injection moulding of low-contaminated permanent magnets.

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Concrete Programming Model for computer with quantum accelerator

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Infrastructure et Ateliers Logiciels pour Puces

01-10-2020

SL-DRT-20-0364

Henri-Pierre.Charles@cea.fr

(.pdf)

Quantum computers will provide unprecedent performances thanks to a very different computing model from the classic computers. The information medium is no longer a 2 states bit but a qbit carrying analog information. Besides, the possibility of entangle a multitude of qbits and manipulate them in a coherent way will provide unprecedented computing power. These quantum computers, with specific applications, will be accelerators of for conventional computers and can not carry a full application. This type of heterogeneous architecture already exists: a GPU or a DSP are pro- grammed from a conventional processor. But in this case the calculation models are similar and the data use the same representation: the two's complement binary format to integer numbers, the IEEE 754 format for floating point numbers, UNICODE for characters, etc. In a quantum machine (as in the vision of DELFT University [3]), it will be necessary to mix two types of very different calculation models (Von Neumann and Quantum models) and data representation spaces that are also different. This thesis will explore different calculation models and ways to move from one model to the other. A programming language and tools for compilation to implement algorithms and make them operate on different platforms (hardware or simulated) will be the main outcome of the thesis. The candidate will have to learn and synthesize a certain number of knowledge: current quantum machines (via platforms of simulation and/or real machines), take into account the characteristics of the physical qbits performed at LETI, discover the calculation models adapted to quantum computation (ZX calculus [2]), assimilate the algorithms / applications [6] known in the quantum field. The subject is pluridisciplinary complex, but CEA is an ecosystem where all this knowledge is present both in the design of physical qbits, in the design of physical qbits, in the electronic, in terms of computer architecture and languages and UGA will provide knowledge, both at the algorithmic level and at the model level of programming level. Through the synthesis of knowledge, the candidate will propose new way to program quantum accelerators in connection with current programming languages [7] based on pre-existing models such as the calculated ZX [2]. With a classic part for the control and access to data and a quantum part for the accelerated part of the program. The classical applications [6] of the domain can be used as benchmarks and will demonstrate the value of the approach, other algorithms will be studied to identify possible candidate for quantum acceleration. [1] H. Bohuslavskyi, A. G. M. Jansen, S. Barraud, V. Barral, M. Cassé, L. Le Guevel, X. Jehl, L. Hutin, B. Bertrand, G. Billiot, G. Pillonnet, F. Arnaud, P. Galy, S. De Franceschi, M. Vinet, and M. Sanquer. Cryogenic subthreshold swing saturation in fd-soi mosfets described with band broadening. IEEE Electron Device Letters, 40(5):784787, May 2019. 3 [2] Niel de Beaudrap and Dominic Horsman. The ZX calculus is a language for surface code lattice surgery. arXiv preprint arXiv:1704.08670, 2017. [3] X. Fu, L. Riesebos, L. Lao, C. G. Almudever, F. Sebastiano, R. Versluis, E. Charbon, and K. Bertels. A Heterogeneous Quantum Computer Architecture. In Proceedings of the ACM International Conference on Computing Frontiers, CF '16, pages 323 330, New York, NY, USA, 2016. ACM. [4] Harald Homulle, Stefan Visser, Bishnu Patra, Giorgio Ferrari, Enrico Prati, Car- men G. Almudéver, Koen Bertels, Fabio Sebastiano, and Edoardo Charbon. Cry- oCMOS Hardware Technology a Classical Infrastructure for a Scalable Quantum Computer. In Proceedings of the ACM International Conference on Computing Frontiers, CF '16, pages 282287, New York, NY, USA, 2016. ACM. [5] Louis Hutin, Benoit Bertrand, Yann-Michel Niquet, Jean-Michel Hartmann, Marc Sanquer, Silvano De Franceschi, Tristan Meunier, and Maud Vinet. SOI MOS Technology for Spin Qubits. ECS Transactions, 93(1):3536, October 2019. [6] Ashley Montanaro. Quantum algorithms: an overview. November 2015. [7] Benoît Valiron, Neil J. Ross, Peter Selinger, D. Scott Alexander, and Jonathan M. Smith. Programming the quantum future. Communications of the ACM, 58(8):52 61, 2015. [8] Rodney Van Meter and Clare Horsman. A Blueprint for Building a Quantum Com- puter. Commun. ACM, 56(10):8493, October 2013.

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Investigation of manufacturing process related structure and performance of fuel cell electrode

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Composants Pemfc

01-10-2020

SL-DRT-20-0365

arnaud.morin@cea.fr

(.pdf)

Zero emission automotive using hydrogen as a fuel and powered by a proton exchange membrane (PEM) fuel cell are now commercially available. However, large-scale commercialization of PEM fuel cell vehicles requires progress in performance, cost and durability, for which the electrode is the most limiting component. It is made of a random assembly of platinum based nanoparticles within a proton conducting polymer network. The electrode is obtained from a slurry after evaporating the solvents. Currently, research and development to improve the performance of the electrode and reduce the cost of manufacturing rely on a trial and error basis. The goal of this project is to increase the knowledge on the relationships between ink composition, electrode structure, properties and performance. The evolution of the ink during the drying process and the so obtained electrode will be characterized using neutron and X-Ray scattering, as complementary tools to unravel the organization of the catalyst material and of the polymer. By correlating these results with Operando electrochemical, structural and imaging measurements, we aim at rationalizing the design of the electrodes. This project involves partners having all the complementary skills needed for this study of most interest for the industrial partner, which is a leader in the research, development and production of fuel cell cars.

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Design of neural networks adapted to FHE and MPC

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire composants logiciels pour la Sûreté et la Sécurité des Systèmes

01-10-2019

SL-DRT-20-0388

aymen.boudguiga@cea.fr

(.pdf)

In this thesis, the student will investigate the variety of scenarios in which homomorphic encryption provides a meaningful countermeasure to confidentiality threats applying to neural net systems. To do this, she/he will leverage on the many degrees of freedom in neural network design as well as homomorphic encryption scheme design to propose specialized networks and FHE-schemes efficiently working together. The candidate will attempt to push this application/FHE co-design strategy to its limits in order to notably: evaluate deep neural networks over encrypted data (input/output privacy), evaluate encrypted deep networks over clear or encrypted inputs (model/output privacy with optional input privacy). This will require to define an efficient FHE-neuron as well as to bring privacy-by-design at all stages of its lifecycle: from the unitary encrypted-domain execution of the neuron itself, to input-private and/or model-private evaluation of networks of that neuron, and then up to the training of networks of such neurons (over clear data). In addition, she/he will investigate the use of MPC for the same evaluations. Ideally, she/he will identify situations where using either FHE or MPC are more suitable for ensuring data confidentiality. In addition, synergies between FHE and MPC usage will be studied. Furthermore, implementing proof of concepts will provide clear experimental evidences of either the practicality of marrying a neural network technique with a specific homomorphic encryption or MPC scheme or measuring/estimating the remaining gap to achieve the evaluation of networks of practically relevant size and complexity.

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Proved simplification engine for software deductive verification

Département Ingénierie Logiciels et Systèmes (LIST)

Laboratoire pour la Sûreté du Logiciel

01-09-2020

SL-DRT-20-0396

loic.correnson@cea.fr

(.pdf)

The Frama-C platform developped at CEA is dedicated to formally establish the absence of bugs in critical sofwares. It is used at an industrial scale in various domains, such as avionics and energy production plants. No asses such waranties on critical sofwares, it is necessary to automate the verfication process with proof assistants (Coq, PVS, HOL) and SMT solvers (Z3, CVC4, Alt-Ergo). However, for these techniques to be applicable on industrial codes, it is necessary to first simplify our proof objectives. Inside Frama-C, we have developped the Qed engine which is precisely in charge of building and simplifying logical formula. This engine was typically responsible for dramatic gains in performance for proving critical codes at Airbus, leading to the adoption of the approach in their production process. Since Qed early developments in 2015 the engine has been extended with many improvements with an increasing complexity. It now becomes difficult to certify that the engine remains sound and only produce valid simplifications. To this end, the subject of the thesis is to completely redesign the Qed engine with the Why-3 proof environment by specifying its simplification algorithms and formally verifying their correctness. Eventually, the extracted code from this Why-3 development will replace the existing engine inside Frama-C.

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Hardware countermeasure techniques of cryptographic algorithms exploiting in-memory computing

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Intégration Silicium des Architectures Numériques

01-10-2020

SL-DRT-20-0401

simone.bacles-min@cea.fr

(.pdf)

The LISAN Laboratory (Digital Design & Architecture Laboratory) develops and designs innovative chip systems based on multicore architectures and low-power architectures dedicated to the Internet of Things (IoT). The field of IoT overcomes many prerequisites, especially in the area of security of autonomous connected objects in energy. New architectures are supposed to be the most energy efficient as possible. The implementation of IoT security must also be guided by the available energy without causing any security breach. An intelligent memory, called C-SRAM, able to perform in memory computing has been designed within the laboratory. The aim of the thesis is to study the possibilities of this memory from the point of view of security. The intrinsic properties of this intelligent memory make it possible to envisage the implementation of several algorithms and in particular new countermeasures against combined physical attacks (side-channels and faults).

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Integration of ULP neurons network based on Injection Locked Oscillators

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Intégration Gestion d'Energie Capteurs et Actionneurs

01-09-2020

SL-DRT-20-0418

franck.badets@cea.fr

(.pdf)

Neural Networks have demonstrated their superiority compared to Von Neumman computing machines for complex classification tasks. Embedding neural networks near the sensors (Edge IA) is a promising way to afford decision autonomy to sensor nodes. This could lead to a global decrease of the power consumption of sensor networks by decreasing the information rate between the nodes and the calculation center which will have also to provide a smaller amount of calculation. Decreasing the power consumption of neurones is a hot research topic as it is a key toward Edge IA. Beside digital implementations, some analog implementations are proposed, but these solutions are bulky and their power consumption is still high. The aim of the thesis work is to demonstrate the feasibility of the implementation of a neural network using Ultra Low Power Injection Locked Oscillators as neurones. Thesis work should lead to the silicon demonstration of learning ability of such networks. Applicant should have a good knowledge of statistical learning and neural networks in particular. He should have good knowledge of analog electronics. Theoretical study will necessitate strong expertise on both mathematics and modelling using python

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Advanced nanocomposites for additive manufacturing

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire Synthèse et Intégration des Nanomatériaux

01-10-2020

SL-DRT-20-0419

thomas.pietri@cea.fr

(.pdf)

The proposed scientific objectives are at the crossroads of nanomaterials and additive manufacturing. Various 3D printing technologies of polymeric matrices have been developed, allowing a conversion of a numerical model with a great precision. But, due to the very recent development of these technologies, the currently available materials appear insufficiently mature and require significant improvements. A great chance of success for properties enhancement could certainly come from the fabrication of advanced nanocomposites (through inclusion of nanomaterials within a polymeric matrix). The work that will be carried out during his PhD will take advantage of the synthesis and functionalization of one-dimensionnal nanomaterials (nanowires, nanotubes). After characterization of the intrinsic properties of the nanocomposites, printable wires will be produced and used with 3D printers. High performance nanocomposites will be used for the fabrication of 3D elements with high conduction of electricity and/or heat. Applications for health will also be considered.

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Study of dynamic degradation and reliability of advanced GaN on Si power devices

Département Composants Silicium (LETI)

Laboratoire de Caractérisation et Test Electrique

01-10-2020

SL-DRT-20-0430

william.vandendaele@cea.fr

(.pdf)

GaN-on-Si based power devices are now considered as the next generation of mass market devices for high frequency & low looses power converters (DC/DC, AC/DC or DC/AC). In this vision, LETI is developing its own pîlot line of GaN on Si power devices (CMOS compatible) from the GaN epitaxy to the final power module. These devices are supposed to operate dynamically between high voltage stage (650V and below) and high current state (> 20A) at high frequencies (> 100kHz). Statics and dynamic performances being proved, it is worth of interest to test and study reliability of these devices under high voltage stress and high temperature as well as under practical swithching conditions (hard/soft/ZVS). These studies aim to understand the underlying physical degradation mechanisms arising under operating conditions and ultimately to stabilize the technologie for industrial technological transfer. The PhD student will be responsible of : - Finalizing exisiting dynamic setups and create new ones especially concerning on-wafer switching test (limitations/feasibility) - In Depth study of HEMT electrical parameters degradation (Ron, Vt, Sw?) as well as Diode parameters (Vf, Sw) during DC or AC stress to determine the root cause of the degradation leading to reliability reduction. - Determination of Switching SOA of GaN based devices from LETI as well as studying new acceleration factors such as duty factor or switching frequency - Localization and Identification of Failure point and understanding of the Failure root cause through FA studies (IR or visible camera + FIB/MEB studies) - Proposal of new technological solutions to overcome some early failures and low realiblity issues The PhD student will be curious, open minded and team worker.

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Optimization of dielectric/GaN interface for MIS gate power devices

Département Composants Silicium (LETI)

Laboratoire Composants Electroniques pour l'Energie

01-09-2020

SL-DRT-20-0432

laura.vauche@cea.fr

(.pdf)

To definitively penetrate into the power electronics market, one of the main challenges for GaN remains the development of a reliable normally-off HEMT solution. In the case of GaN-based MIS channel-High Electron Mobility Transistors (HEMTs), the dielectric/GaN interface properties are critical. The goal of the thesis is to optimize the dielectric/GaN interface for MIS gate power devices. For this, 1. The dielectric/GaN interface properties will be evaluated by XPS (X-ray Photoelectron Spectroscopy). This technique allows to study the oxidation degree at GaN surface. Additional analyses by ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) and HRTEM (High Resolution Transmission Electron Microscopy) will be carried out in order to characterize the materials chemical composition and crystalline structure. 2. GaN-based devices quality will be studied by transistor and capacitance electrical characterization (mobility, on-resistance, channel resistance, threshold voltage, hysteresis), as well as fine electrical measurements (interface state density extraction reliability). 3. The impact of processing steps (wet chemical cleaning, etching, stripping, thermal and plasma treatments)on interface quality will be evaluated, allowing to select the most appropriate MIS gate processing.

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Point-of-Care medical device development for high sensitivity multiplexed detection of blood biomarkers for health care management of cardiac patients

Département Microtechnologies pour la Biologie et la Santé (LETI)

Laboratoire Biologie et Architecture Microfluidiques

01-09-2020

SL-DRT-20-0451

myriam.cubizolles@cea.fr

(.pdf)

Health systems must adapt to new societal and economic constraints that constitute an important challenge to address for the health of tomorrow. In this context, the development of Point-of-Care (POC) devices to carry out in vitro analyses provide valuable assistance to the decision-making of the practitioner for the diagnosis and/or prognosis of the disease. In this context, we propose a PhD subject to explore a new strategy to quantify blood biomarkers (proteins, peptides). This strategy is an alternative to the ELISA gold standard method, based on immuno-detection coupled to enzymatic amplification. We propose an innovative approach to develop a medical device for the high sensitivity detection of various significant blood biomarkers for cardiac diseases. The employed strategy is based on the use of original reagents (aptamers) allowing an isothermal multiplex biomolecular amplification, fast and highly sensitive, coupled with protocol integration and automation inside dedicated microfluidic cartridges. The developed biomedical device will be tested on clinical samples.

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Microstructural changes in additive manufacturing materials during Hot Isostatic Pressing: modelling and experimental study

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire Conception et Assemblages

01-10-2020

SL-DRT-20-0470

emmanuel.rigal@cea.fr

(.pdf)

Additive manufacturing (AM) processes are promising techniques for manufacturing metallic components from powder or wire feedstock. AM materials exhibit microstructures very different from cast or forged equivalent materials. They are out of equilibrium, sometimes anisotropic, with specific features like a high dislocation density and defects (unmelted particles, pores) which may be detrimental to mechanical properties (creep, fatigue resistance). Defects can be mitigated using a heat treatment under high gas pressure (hot isostatic pressing HIP), at the expense of material softening. The objective of the PhD thesis is to model the microstructural évolutions during HIP in order to optimise the HIP cycle for a given AM microstructure: defects shall be decreased enough while softening shall be limited. A detailed characterisation of the initial microstructure will be done (defects, grain size, dislocation density, precipitates, texture?) in order to provide data for the DIGIMU software. This software uses the level set method to simulate, by finite element calculation, the evolution of a volumic element representative of a microstructure during thermomechanical loading. This software will be enriched. The comparison between modelled evolution and experimentally observed ones will be used to assess the relevancy of the modelling (HIP will be applied on samples). Furthermore, attention will be paid to the evaluation of the impact of the HIP treatment on mechanical properties of AM material (316L steel will be used).

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5G mmW integrated BiDirectional TRX for hybrid and digital beamforming system

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Architectures Intégrées Radiofréquences

01-10-2020

SL-DRT-20-0478

baudouin.martineau@cea.fr

(.pdf)

This thesis addresses the topic of compact, low-cost millimeter wave transceiver in the context of the new coming 5G FR2. Indeed, a considerable number of chips and an area-efficient design will be necessary for hybrid and digital MIMO beamforming. However, conventional transceiver designs use switch-based bidirectional approach with one Tx and one Rx working alternatively in time duplex. For this reason, bi-directional transceiver completely sharing amplifiers and matching networks between the transmitter and the receiver is proposed. Additionally, bidirectional phase shifter, quadrature mixer and baseband amplifier will be studied and design offering a complete solution for hybrid and digital beamforming architecture. The thesis study will cover the architecture, the design and the measurement of such blocs in standalone and the full transceiver. The awaited innovation will encompass several aspect: bidirectional front-end compatible with hybrid configuration, mmW digital beamforming compatible, LO multiplication and local quadrature generation, CMOS SOI process. This phd research will give the opportunity to work in cross-scientific disciplinary from millimeter wave to baseband design and transceiver system architecture offering a very large panel of experiences and competencies. The thesis will take place in the CEA Leti institute under the supervision of Mr Martineau Dr and Mr Belot Hab. The publication in journals and international conferences will be encouraged and facilitated.

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Study of Vertical GaN Device Architectures

Département Composants Silicium (LETI)

Laboratoire Composants Electroniques pour l'Energie

01-10-2020

SL-DRT-20-0481

julien.buckley@cea.fr

(.pdf)

LETI is currently transferring an AlGaN/GaN epitaxy-based power device technology on 200mm Silicon wafers to a well-established industrial partner in the field of power devices (Silicon, SiC,?) Current GaN transistor technologies that are available on the market have a lateral architecture. They allow to render electric power conversion circuits up to the several 10 kilowatt range. The implementation of a vertical architecture will allow to address power ranges above the megawatt. The work proposed in this PhD will involve a study aiming to evaluate the performance and physical properties at the basis of the operation of vertical devices using GaN substrates. The tasks will involve as well the management of the device fabrication (epitaxy, deposition, lithography, implantation) and electrical measurements. Finite element simulations (TCAD using Synopsys tools) will be performed in order to tune the dimensions of structures that will be included in a mask set and subsequently be used to test physical hypotheses to interpret the electrical results.

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Aluminum/ Silicon carbide nanocomposites obtained by laser powder bed fusion additive manufacturing process.

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Formulation des Matériaux

01-11-2020

SL-DRT-20-0483

mathieu.soulier@cea.fr

(.pdf)

Metal matrix composite composed of an aluminum metal matrix embedding silicon carbide inclusions is widely used in various industries from automotive to aerospace or defense. Such composites allow the reduction of the parts weight thanks to an increase of the Young modulus/density ratio drastically higher compared to steels or titanium alloys. The study aims at developing aluminum composites reinforced by nanosized silicon carbide particles to improve the material stiffness without compromising on the elongation to fracture criterion. In addition, shaping by an additive manufacturing process based on a laser powder bed fusion process (L-PBF) should allow further improvements in terms of weight reduction, thus fully complying with the strategical objectives of material savings and environmental impact. The first objective of the thesis is to develop the powder mixing process to obtain homogeneous and stable nanocomposite powder, using either a blade mixing to coat aluminum particles by the nano SiC, or a milling process to include the reinforcements inside the aluminum particles. For the case of blade mixing, the challenge is to identify process conditions that allow an homogeneous repartition of the nano-Sic within the solidified material. The second objective of the thesis is to test the potential of tailored specific nano-SiC reinforcements. To this end, the idea is to use the laser pyrolysis process that allows a modification of the surface chemistry to improve the SiC wettability and also limit its decomposition in the aluminum matrix.

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Piezoelectric MEMS actuator hydraulically amplified

Département Composants Silicium (LETI)

Labo Composants Micro-actuateurs

01-09-2020

SL-DRT-20-0488

laurent.mollard@cea.fr

(.pdf)

The main objective of micro-actuators research is an architecture that can generate large displacements and forces over a wide frequency range, while not consuming a significant amount of electrical power. To date, no solution meets all these criteria. Indeed hydraulic actuators do not meet the criterion of compactness and frequency but allow significant force and displacement. Similarly, electromagnetic actuators have a good frequency range with excellent force and stroke output, but they are generally heavy and require significant electrical current. Piezoelectrics are also known for their excellent operating bandwidth and can generate large forces in a compact size, but traditionally they have very small displacements. The technological breakthrough of the thesis will consist to develop a hydraulic amplification mechanism, by applying small displacements on a large surface, sa as to move a liquid, and to generate, by conservation of the volume, important displacements on a weaker moving surface. Therefore, the thesis will consist to develop and integrate into a MEMS (Micro Electro-Mechanical System) system, this hydraulically amplified piezoelectric actuator (called HDAM system for "Hydraulic Displacement Amplification Mechanism") and optimize it

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ultra low temperature solid phase recrystallization assited by nanosecond laser annealing

Département des Plateformes Technologiques (LETI)

Laboratoire

01-09-2020

SL-DRT-20-0514

Pablo.ACOSTAALBA@cea.fr

(.pdf)

During last years, great progress has been made in reducing the thermal budget required for the manufacture of microelectronics devices. Moreover, nanosecond laser annealing represents a very promising alternative for the integration of microelectronic devices whose thermal budget must be limited. Since very few years, CEA/LETI has started a very ambitious program on advanced thermal treatments for microelectronics. In this context, a nanosecond laser annealing equipment has been installed in the LETI clean room. This innovative process makes it possible to reach very high temperatures for extremely short durations (a few tens of ns). This implies that the thermal budget applied to the irradiated structures is very low. It has recently been demonstrated that nanosecond laser annealing can be used to obtain solid phase recrystallization of partially amorphized silicon layers. This method can be used to optimize different steps of the manufacturing processes, as for exemple dopant activation on source and drain. It is therefore fundamental to understand the physical mechanisms and to explore the impact of different parameters on the recrystallization kinetics in order to manage this process in basic materials such as Si and SiGe. This thesis aims evaluating the contribution of nanosecond laser annealing on the structural and electrical properties of different semiconductor stacks

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Lensless imaging and artificial intelligence for rapid diagnosis of infections

Département Microtechnologies pour la Biologie et la Santé (LETI)

Laboratoire Systèmes d'Imagerie pour le Vivant

01-10-2020

SL-DRT-20-0518

caroline.paulus@cea.fr

(.pdf)

The objective of the thesis is to develop a portable technology for pathogen identification. Indeed, in a context of spread of medical deserts and resurgence of antibiotic-resistant infections, it is urgent to develop innovative techniques for rapid diagnosis of infections in isolated regions. Among optical techniques for pathogen identification, lens free imaging methods draws attention because they are the only ones currently able to offer simultaneous characterization of a large number of colonies, all with low-cost, portable and energy-efficient technology. The objective of the thesis is to explore the potential of lensless imaging combined with artificial intelligence algorithms to identify bacterial colonies present in a biological fluid. The thesis will aim to optimize the sizing of the imaging system (sources, sensors) and to study image processing and machine learning algorithms necessary for colony identification. Two cases of clinical applications will be studied.

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Improvement of CdZnTe based gamma imager CdZnTe using machine learning

Département d'Optronique (LETI)

Laboratoire Architecture Systèmes Photoniques

01-11-2020

SL-DRT-20-0522

gmontemont@cea.fr

(.pdf)

Gamma imaging is a technique widely used in medical imaging (molecular imaging, nuclear medicine) and security (transportation, industry). CdZnTe semiconducting detectors usage is currently emerging for SPECT (Single Photon Emission Computed Tomography, using gamma-cameras) and portable gamma imaging. Indeed, they enable performance improvements in speed, sensitivity and image quality. These detectors operate at room temperature and are sensitive to five physical parameters of the interaction: deposited energy E, interaction time T and the 3-dimensional position XYZ. These parameters are estimated by real-time analysis of anode electronics signals. However, the link between electrical signals and physical parameters is not fully known, as material physical properties are not uniform inside detector. The goal of this Ph.D. internship is to overcome these limits by using machine learning techniques to model actual detector response. Recent multi-layered deep learning technique enable to build and train complex and flexible system models, and to overcome our lack of knowledge about detector physics. The identification of internal physical parameters of the detector would allow to optimize estimation of interaction location, time and energy. This will lead to a better image quality and then capability to detect small and weak objects, enabling better diagnoses and lower false alarm rate. The student may have a background in applied mathematics (machine learning) and/or instrumentation physics. He/she need to have taste for multi-disciplinary research, mixing experimental physics and data science.

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Ecodesign methodology for new generations of batteries

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des Eco-procédés et EnVironnement

01-10-2020

SL-DRT-20-0535

elise.monnier@cea.fr

(.pdf)

The development of the electrification of vehicles requires the design of cheaper and more efficient battery technologies. In response to this demand, many development paths are under study, such as new generations of Li-ion with reduced cobalt content or high energy density, all solid state lithium batteries or Li-Sulphur batteries, among other. Apart from the performance aspect, there is a real need to assess the environmental impact of these technologies over their entire life cycle (LCA), and to look at eco-design options for the development of the batteries of the future. The proposed thesis will aim at addressing these issues, using a multidisciplinary approach combining the skills of at least three laboratories from CEA LITEN. At the end of the thesis, the expected results will be: an environmental evaluation of the 3 new generation of battery technologies (advanced Li-Ion, Li-S and All-Solid), compared to reference battery technologies as well as an eco-design methodology to guide decision support in the development of low TRL battery technologies.

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Applied formal semantics in hardware compiler frameworks

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire composants logiciels pour la Sûreté et la Sécurité des Systèmes

01-10-2020

SL-DRT-20-0540

Mihail.Asavoae@cea.fr

(.pdf)

The development of RISC-V instruction set architecture (ISA) is supported by new methodologies and tools which are dedicated to increase the productivity of hardware designs (i.e., high-level design languages and specialized compilation chains). At the language level, Chisel and FIRRTL Hardware Description Languages (HDLs) aim to raise the level of abstraction of hardware design. It thus becomes appealing to formally reason on functional and temporal properties of these high-level designs and rely on appropriate compilation extensions to transfer these high-level properties down to the level of generated Verilog, for example. In this PhD proposal, we target a formal verification framework for computer architectures to support the specification and verification of timing-related safety and security properties. The following two contributions are expected of this PhD thesis: 1) the design and implementation of a verification infrastructure based on formal executable semantics of Chisel and FIRRTL HDLs and 2) the design and implementation of an assertion language to express timing safety and security properties, which are to be verified with the aforementioned formal infrastructure. The scientific contributions of this thesis are expected to evaluated on a selection of the rich-set of architecture designs provided by the RISC-V ecosystem.

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Porous structures of hydrogenated nanodiamonds for CO2 transformation in exploitable products

Département Métrologie Instrumentation et Information (LIST)

Laboratoire Capteurs Diamants

01-10-2020

SL-DRT-20-0571

(.pdf)

Since its identification as a source of solvated electrons usable for photocatalysis, hydrogenated bulk diamond is actively investigated for CO2 reduction. This behaviour is conferred by the C-H dipoles present at the surface that favor the electron emission to the interface with surrounding media. Moreover, its electronic structure (negative electron affinity) allows the emission of photoelectrons, able to initiate the CO2 reduction at one electron or to form solvated electrons. Hydrogenated nanodiamonds behave a similar electronic structure as we demonstrated few years ago. This PhD aims first to elaborate porous materials using diamond nanoparticles via innovative and scalable technics to allow a tunable and efficient use for CO2 reduction. Performances for CO2 reduction will be then evaluated while mechanisms involved in the production of reducing species under illumination will be investigated via a more fundamental approach. The first barrier concerns the elaboration of nanocomposite porous matrix fabricated from hydrogenated diamond particles for photo(electro)catalysis. An original process (HIMAYALAN) developed at LEDNA, combining nanoparticles jets under vacuum to magnetron sputtering, will be used. Porous layers of nanoparticles embedded in another material (silica or amorphous carbon) will be fabricated exhibiting a very high porosity. A co-doping of such composites with metallic particles is also performed to improve the optical absorption performances. A proof of concept is currently under progress with the Bottom-up project CORAIL. The second obstacle corresponds to the boron doping of diamond particles (size 10 to 200 nm) which confers it an electrochemical activity. In that case, their catalytic efficiency can be enhanced applying a bias. Different synthesis routes are considered: from the milling of boron doped diamond films (commercial particles) to a more innovative and scalable approach based on the synthesis of core shell boron doped diamond. The former process patented at LCD will be developed during an ANR PRCE project starting in April 2020. The second aspect of this PhD concerns the evaluation of porous nanocomposite diamond layers for the CO2 reduction via photo(electro)catalysis. A dedicated set-up will be developed at LCD including a lamp and the ability to work under CO2 pressure. The crystalline structure and the properties of hydrogenated boron doped diamond particles will be investigated using SOLEIL Synchrotron facilities. Relations with their photocatalytic performances will allow to improve their efficiency. XPS studies on isolated particles will be achieved on PLEIADES beamline to extract the surface structure at the atomic level and the location of heteroatoms. Photo-ionisation and photo-fragmentation studies versus the wavelength of incident radiation will be performed on DESIRS beamline.

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Side-Channel Analysis against the confidentiality of embedded neural networks: attack, protection, evaluation

Département Systèmes (LETI)

Laboratoire Sécurité des Objets et des Systèmes Physiques

01-09-2020

SL-DRT-20-0584

pierre-alain.moellic@cea.fr

(.pdf)

One of the major trends of Artificial Intelligence is the large-scale deployment of Machine Learning systems to a large variety of embedded platforms. A lot of semi-conductor practioners propose "A.I. suitable" products, majoritarely with neural networks for inference purpose. The security of the embedded models is a major issue for the deployment of these systems. Several works raised threats such as the adversarial examples or the membership inference attacks with disastrous impact. These works consider the ML aglorithms through a pure algorithmic point of view without aking into consideration the specificities of their physical implementation. Moreover, advanced works are compulsory for physical attacks (i.e., side-channel and fault injection analysis). By considering a overall attack surface gathering the theoretical (i.e. algorithmic) and physical facets, this subject propose to analyze side-channel analysis threats (SCA) targeting the confidentiality of the data as well as the model (reverse engineering) of embedded machine learning systems and the development of appropriate protections. Several works have studied physical attacks for embedded neural networks but with usually naive model architecture on 'simple' 8-bit microcontrolers, or FPGA or at a pure simulation level. These works do not try to link the fault models or the leakages with well-known algorithmic threats. Being based on the experience on other critical systems (e.g., cryptographic primitive), the main idea of this PhD subject will be to jointly analysis the algorithmic and physical world in order to better understand the complexity of the threats and develop efficient defense schemes. The works will answer the following scientific challenges: (1) Caracterization and exploitation of side-channel leakages: how to exploit side-channel leakages (power or EM) to guess sensible information focused on the training data or information on the model architecture. (2) Evaluation of the relevance of classical countermeasures such as hiding or masking techniques for this kind of systems and threats. (3) Develop new protections suitable to embedded neural networks.

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Optomechanical reference oscillators

Département Composants Silicium (LETI)

Laboratoire Composants Micro-Capteurs

01-09-2020

SL-DRT-20-0592

marc.sansaperna@cea.fr

(.pdf)

Clocks (reference oscillators) are ubiquitous elements in electronic circuits. The arrival of new technologies such as 5G or autonomous vehicles requires a level of performance that is not attainable by commercial clock technologies. One of the most promising routes to improve performance is the development of clocks based on micro-electromechanical (MEMS) resonators at high frequency (1-5 GHz, tens of GHz in the future). However, it is challenging to build high-performance MEMS resonators in the GHz range, mainly due to the difficulty of detecting their minuscule vibration amplitudes. Recently several groups have demonstrated the possibility of building optomechanical devices in piezoelectric materials. This technology, which was confined to fundamental studies, is now mature enough to evolve towards applications, and solves many of the difficulties involved in the implementation of MEMS clocks in the GHz range. The objective of the thesis is to develop a MEMS clock based on this novel optomechanical technology. The thesis will take place in the Microsensors Laboratory of the CEA-Leti, in collaboration with the RF Components Laboratory. The Leti is a pioneer in the implementation of on-chip optomechanical and piezoelectric resonators. The PhD student will work in collaboration with Leti Engineers to design the MEMS resonators and their fabrication process, based on an analytical study and finite-element simulations. Then, the student will have the opportunity to contribute to the fabrication of the devices in clean room. Finally, the student will characterize them in the Leti's laboratories, to extract their performance and implement a first demonstrator of MEMS clock.

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Protecting elliptic curve cryptography against Template atttacks and Horizontal attacks

Département Systèmes (LETI)

Laboratoire Sécurité des Objets et des Systèmes Physiques

01-09-2020

SL-DRT-20-0600

antoine.loiseau@cea.fr

(.pdf)

This study is focused on the security of embedded systems and in particular asymmetric cryptography against horizontal attacks and Template attacks. Recent studies, applied to symmetric cryptography, have made it possible to build new techniques for side channel attacks. By improving the effectiveness of Template attacks, these new attacks make it easier to bypass masking countermeasures. It seems appropriate to study these new tools in depth in the context of Template and horizontal attacks against asymmetric cryptography, especially for elliptic curves. The use of machine learning in the context of side channel attacks. The main purpose of the thesis is to evaluate the security properties of ECCs against the most advanced Template and Horizontal attacks that use machine learning. Depending on the results obtained, new countermeasures will have to be constructed in order to address any new weaknesses.

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Optimisation de l'électrode Ni-YSZ à hydrogène pour une durabilité améliorée des cellules à oxydes solides

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire Production d'Hydrogène

01-10-2020

SL-DRT-20-0602

karine.couturier@cea.fr

(.pdf)

Solid oxide cells (SOCs) are electrochemical devices operating at high temperature that can directly convert fuel into electricity (fuel cell mode ? SOFC) or electricity into fuel (electrolysis mode ? SOEC). In recent years, the interest on SOCs has grown significantly thanks to their wide range of technological applications that could offer innovative solutions for the transition toward a renewable energy market. Indeed, the SOCs present various advantages, such as a good reversibility, a large fuel flexibility and a very high efficiency. Despite these advantages, the degradation in performances of SOCs is still too high to envisage the industrial deployment of this technology. Among the different degradation phenomena, the microstructural evolution of the fuel electrode, which is classically made of Nickel and Yttria stabilized Zirconia (Ni-YSZ cermet), is recognized to contribute significantly to the cell ageing. In this PhD thesis, the degradation mechanisms of the Ni-YSZ electrode will be studied. For this purpose, an integrated experimental and modelling approach will be adopted coupling (i) electrochemical testing, (ii) modeling and (iii) advanced post-test microstructural characterization. Once the mechanisms of degradation precisely understood, solutions for mitigating the degradation will be proposed via material and microstructural optimizations.

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Low-frequency wireless power transmission for autonomous systems

Département Systèmes (LETI)

Laboratoire Autonomie et Intégration des Capteurs

01-09-2020

SL-DRT-20-0615

pierre.gasnier@cea.fr

(.pdf)

Wireless power transmission (WPT) technologies are expanding rapidly, particularly for wireless charging of electrical systems (phones, electric vehicles, etc.). However, these technologies have a limited transmission range and their high operating frequency prohibits any transmission of energy in the presence or through conductive media (metal walls or seawater), which limits their adoption in complex environments (industrial, military...). The low-frequency WPT technology we propose is based on an electromechanical system comprising two coils and a magnet. This type of technology has the advantage of being able to power wireless sensor nodes for a variety of applications (health monitoring of structures in isolated environments is one example among others). The purpose of the thesis is to study the addition of a piezoelectric converter at the receiver side. This so-called "hybrid" system (electromagnetic/piezoelectric) will take advantage of each converter, in order to improve the receiver's performance and ultimately increase the maturity of the technology (increase in range, power densities, etc.). In this context, the thesis will consist in studying, developing and testing the performance of hybrid WPT solutions. The candidate will develop analytical and numerical models to identify the parameters of influence of the coupled system and compare its performance to the literature. The candidate will also have to develop adapted innovative energy conversion electronics. A joint optimization of the electromechanical system and its associated electronics will lead to the development of a complete high-performance wireless power transmission system. The final goal of the thesis is to analyze and understand the advantages and limitations of this hybrid technology. A multidisciplinary profile oriented towards physics and mechatronics is sought for this thesis. In addition to a solid theoretical background, the candidate must have teamwork skills and an ability for experimentation. The student will integrate the Systems Division of CEA-Leti, within a team of researchers with strong expertise in the development and optimization of electronic and mechatronic systems combining innovative solutions for energy harvesting, wireless power transmission, low-power electronics and sensor integration for the development of autonomous systems.

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Degradation Mechanisms of the Lanthanum Strontium Cobalt Ferrite Used as Oxygen Electrode in Solid Oxide Cells

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire Production d'Hydrogène

01-10-2020

SL-DRT-20-0622

bertrand.morel@cea.fr

(.pdf)

Solid oxide cells (SOCs) are electrochemical devices operating at high temperature that can directly convert fuel into electricity (fuel cell mode ? SOFC) or electricity into fuel (electrolysis mode ? SOEC). In recent years, the interest on SOCs has grown significantly thanks to their wide range of technological applications that could offer innovative solutions for the transition toward a renewable energy market. Indeed, the SOCs present various advantages, such as a good reversibility, a large fuel flexibility and a very high efficiency. Despite these advantages, the degradation in performances is still too high to envisage the industrial deployment of this technology. Among the different degradation phenomena, the destabilization of the oxygen electrode, classically made of Lanthanum Strontium Cobalt Ferrite (LSCF), is recognized to contribute significantly to the cell ageing, especially when operated in electrolysis mode. In this context, the aim of the PhD thesis is to investigate the mechanisms controlling the electrode phase demixing and the diffusion of chemical elements. For this purpose, an experimental and modeling approach will be adopted including electrochemical testing and advanced post-test characterizations. Nano-imaging by synchrotron X-ray fluorescence and diffraction will be conducted on the aged electrodes. The acquired data will be implemented in an existing multiscale model to analyze the degradation mechanisms. Finally, recommendations in terms of materials and manufacturing conditions will proposed to improve the cell lifetime.

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Development of innovative chalcogenide material etching processes for non-volatile memories and photonic

Département des Plateformes Technologiques (LETI)

Laboratoire Gravure

01-09-2020

SL-DRT-20-0625

christelle.boixaderas@cea.fr

(.pdf)

The patterning steps (etching / stripping / cleaning) have adverse effects on the properties of chalcogenide films. It is therefore essential to study this patterning brick in order to propose new dry etching solutions and associated post treatments. After a first phase of bibliographic research and training in clean room on tools necessary for future works, the student will propose a methodology allowing the understanding of the mechanisms of etching of the reference process and modifications of the GeSbTe (and other alloys) by surface analyzes (bottom and sidewall of the structures) It will propose and implement improvements to the reference process (chemistry, plasma parameters, etc.) that will ensure that the chalcogenide remains intact during the flow of memory fabrication. Then, he will have to choose the integrations and materials for a test vehicle in memory and Photonics. The challenge will be to make improvements to the reference process of the memory stack based on the study of the previous phase: stack etching, stripping, management of waiting times between stages. Finally, it would be interesting to measure the impact of the changes by electrical results on the memory cells (gain / loss on the intrinsic characteristics of a PCM memory).

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Development of cellulose-based materials for the conception of biomedical devices by stereolithograpy

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Formulation des Matériaux

01-11-2020

SL-DRT-20-0628

sebastien.rolere@cea.fr

(.pdf)

The development of innovative medical devices mainly relies on the use of high performance multifunctional materials. These materials should display high biocompatibility and controlled degradability, and advantageously specific biological properties, such as muco-adhesion, antimicrobial features, or bioaffinity. Such advanced materials are keys for biomedical research activities. Additive manufacturing technologies are particularly well-suited for the technical specifications of biomedical devices. Notably, StereoLithography Apparatus (SLA) allows the processing of complex geometries from UV-light curing of liquid materials. SLA is currently under consideration to develop biomedical devices from cellulose materials. Cellulose is a biocompatible bio-based polymer, extracted from renewable resources. Cellulose chemical structure possesses many hydroxyl functional groups for potential chemical modification and further biomolecules attachment. The aim of the present project is the design and fabrication, using SLA, of biomedical devices able to present various bio-specific properties, from chemically-modified cellulose materials.

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Ferroelectric Tunnel Junctions (FTJs) for Memory Applications and Ultra-Low Power Neuromorphic Circuits

Département Composants Silicium (LETI)

Laboratoire de Composants Mémoires

01-10-2020

SL-DRT-20-0635

laurent.grenouillet@cea.fr

(.pdf)

The recent discovery of ferroelectricity in hafnium oxide (HfO2) thin films generates a strong interest to save information in a non volatile way for ultra-low power memories, via the application of an electric field to switch the material's electrical polarization. More recently, preliminary results demonstrating HfO2-based ferroelectric tunnel junctions (FTJs) were reported with this CMOS-compatible and scalable material. Here the ferroelectric layer enables to modulate the tunneling current passing through the junction, depending on its polarization. This opens numerous perspectives to those new devices. The objectives of the PhD work will be to fabricate, characterize and model ferroelectric tunnel junctions to better understand the physics of those devices, and then optimize their performance. The optimized devices will then be co-integrated in the form of arrays above complex CMOS circuits to serve as artificial synapses in an ultra low power neuromorphic processor. This work will be performed in collaboration with european partners in the framework of H2020 BeFerroSynaptic EU project.

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Multi-scale modeling of the electromagnetic quantum dot environment

Département Composants Silicium (LETI)

Laboratoire de Simulation et Modélisation

01-10-2020

SL-DRT-20-0637

helene.jacquinot@cea.fr

(.pdf)

Multi-scale modeling of the electromagnetic quantum dot environment In the near future, emerging quantum information technologies are expected to lead to breakthroughs in the world of high performance computing and secure communication. Among solid-state approaches, ?Silicon on Insulator? (SOI) based spin quantum bit (qubit) is an alternative approach to nowadays superconducting based one [1]. They are much more compact and have demonstrated over the last few years significant achievements, with long coherence time and fast single qubit rotation. A clear challenge is now to investigate the scalability issues going from single to multiple of the spin qubits in SOI, taking into account its associated classical CMOS platform used for control, read-out and initialization of the quantum state [2]. The main goal of this PhD work is to assess different strategies to implement spin control on 2D qubit arrays using microwaves signals. The candidate will i) characterize radio-frequency (RF) test structures at very low temperature using state-of-the-art equipment and compare results with dedicated electromagnetic simulations, ii) develop a toolbox to allow multi-scale optimization from single to qubit arrays, iii) integrate RF spin microwave control for 2D qubit array using CEA-LETI silicon technologies. This PhD work will be performed in the frame of a tripartite collaborative project between CEA-LETI, CEA-IRIG and CNRS-Institut Néel (ERC ?Qucube?). [1] Maurand, R. et al. A CMOS silicon spin qubit, Nat. Communications 7, 13575 (2016). [2] Meunier, T. et al. Towards scalable quantum computing based on silicon spin, Symp. on VLSI Technology, 2019.

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Embedding of high temperature resistant Fiber Bragg Gratings into metal structures obtained by additive manufacturing processes

Département Métrologie Instrumentation et Information (LIST)

Laboratoire Capteurs Fibres Optiques

01-10-2020

SL-DRT-20-0645

guillaume.laffont@cea.fr

(.pdf)

LCFO laboratory from the Technological Research Division at CEA List, in partnership with the LISL laboratory from the CEA DEN, specialized in metal additive layer manufacturing processes, proposes a PhD thesis aiming at developing methods to integrate optical fiber sensors (OFS) based on high temperature resistant Fiber Bragg Gratings (FBGs) in metallic components obtained thanks to metal additive layer manufacturing processes either for the aerospace or for the nuclear industry. Thanks to recent developments, ultra-stable FBGs have been realized using direct writing processes into silica optical fibers with femtosecond lasers. These temperature and strain transducers combined with special optical fibers designed for very high temperature environments will be considered for the instrumentation of components obtained by metal additive layer manufacturing. This project aims at contributing to the adoption of in situ monitoring of 3D-printed metallic components, paving the way for their Structural Health Monitoring (SHM) to anticipate failures in the fabrication process and to optimize operating costs thanks to the development of predictive and conditional maintenance-based procedures.

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Behavior of inorganic elements in supercritical water gasification

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire de Conversion de ressources Carbonées par voie Hydrothermale

01-10-2020

SL-DRT-20-0649

geert.haarlemmer@cea.fr

(.pdf)

To valorize very wet or even liquid carbon resources, a very promising process for energy valorization is the gasification in supercritical water that produces a synthesis gas (mixture of CH4, H2 and CO2). Gasification in supercritical water is based on phenomena related to water properties under high pressure and high temperature. Beyond its critical point (temperature 374 ° C and pressure 22.1 MPa), water becomes a very reactive medium and promotes gasification reactions. Among the resources targeted by this process, we can cite, for example, waste from the agri-food industry (fruit and brewer's grains ...), industrial effluents (black liquor), microalgae, digestates from anaerobic digestion, sewage sludge ... The development of gasification process in supercritical water is at the laboratory pilot scale. Research and development actions are still needed to reach the industrial scale. One of the main barriers is the management of pollutants in the resource such as H2S and the presence of inorganics. The aim of this thesis is to better understand the behavior of salts and pollutants in supercritical water conditions. With this knowledge, an evaluation of the different inorganic and pollutant management strategies is expected, either thermodynamically or chemically, and thus help the laboratory to propose design solutions for future supercritical water gasification pilots.

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Resonators and devices based on elastic waves obtained through the hybridization of surface and bulk waves

Département Composants Silicium (LETI)

Laboratoire Composants Radiofréquences

01-09-2020

SL-DRT-20-0668

alexandre.reinhardt@cea.fr

(.pdf)

Bulk or surface elastic wave devices are currently an enabling technology for radiofrequency emission/reception circuits used in mobile phones. Since, at constant frequency, the wavelength of elastic wave is close to 100,000 times smaller than electromagnetic wavelengths, the treatment of a signal carried by elastic waves instead of an electrical signal offers a tremendous miniaturization. With the increase in frequency bands operated simultaneously by each single mobile phone, requirements brought onto radiofrequency filters become more and more stringent. This motivates the research on new types of components exploiting new elastic waves. Conventional technologies rely on bulk acoustic waves (BAW) or surface acoustic waves (SAW) propagating respectively along the thickness or the surface of a piezoelectric material. Such kind of materials offer the possibility to couple electric signals into elastic waves, and conversely. In the last few years, a new kind of propagation mode, called "hybrid SAW/BAW" has been proposed, based on the excitation of waves by a periodic array of piezoelectric stubs. First realizations have been proposed, but their properties are not yet fully determined. This PhD subject focuses therefore on the study of the potentialities offered by these new kinds of modes. On one hand, the properties of such waves are strongly related to the combination of piezolectric material, of the nature of the substrate, on their respective crystal orientations as well as on the geometric dimensions of the piezoelectric stubs. The candidate will therefore investigate the design space in order to reveal what performances can be expected from such structures and optimise their design towards applications such as RF filters or time references, ideally for applications above 3 GHz. This work will leverage the simulation models available at CEA-LETI and those developped by the FrecNSys company. A second part of the PhD is expected also to explore more fundamental possibilites opened by these modes arising from the coupling between elastic surface waves and a periodic array of electrically active structures. Such periodic structures belong to the broader range of so-called elastic metamaterials, which offer unusual propagation properties such as frequency ranges in which wave propagation is forbidden, artificial slowing of waves, strong confinement or nonreciprocal propagation. Since active structures are involved, additional interesting effects may be explored. The candidate will leverage the expertise on elastic metamaterials brought by the acoustic department of ISEN. Eventually, an experimental part will be devoted to the proposition of designs to be implemented in the clean rooms of CEA-LETI and participation to the technological developments. The goal is here to assess the exprimental feasibility of such structures.

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Hybrid modeling for the simulation of ultrasonic inspection of laminate composite for the detection of inter-plies damages or weaknesses

Département Imagerie Simulation pour le Contrôle (LIST)

Laboratoire Simulation et Modélisation en Acoustique

01-10-2020

SL-DRT-20-0671

nicolas.leymarie@cea.fr

(.pdf)

In the framework of the simulation of ultrasonic non-destructive techniques (UT), we consider to design specific simulation tools dedicated to laminate composites. These materials are nowadays widely used in the aeronautical field but show fragility under dynamic stresses such as impacts. Even for low-energy impacts, composite components can be weakened by localized damage, mainly by transverse cracking and delamination. Due to their anisotropic, heterogeneous and multi-layered properties, the development of UT methods for the inspection of such structures is very challenging. Numerical simulation is therefore useful, both for analysis and for the design and optimization of new UT techniques. Based on innovative numerical works, the aim of this study is to propose numerical methods dedicated to the simulation of new UT methods and in particular to the analysis of oblique incidence controls of realistic damage defects. For this, we will rely on existing developments recently done at CEA LIST based on the transient spectral element method, especially by using effective interface conditions to model a realistic delamination or local porosities in inter-plies matrix.

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Integrated Bioelectrodes and Biopolymer-Microneedle Devices for Transdermal Electrochemical Sensing

Département Microtechnologies pour la Biologie et la Santé (LETI)

Laboratoire Chimie, Capteurs et Biomatériaux

01-10-2020

SL-DRT-20-0673

isabelle.texier-nogues@cea.fr

(.pdf)

Electrochemical sensors have attracted considerable interest owing to their tremendous promise for portable and rapid monitoring of personal health. Current devices are limited to single analyte detection (mostly glucose) in biofluids over short times using invasive sample collection. In this PhD, we propose to combine electro-enzymatic sensor technology with less-invasive, painless microneedle (MN)-based sampling for rapid detection of different biomarkers (e.g. glucose and nitrate) in interstitial fluid. The goal is to establish a sensitive and convenient platform for analyte detection for better metabolic profiling of diabetes and cardiovascular disease. This PhD project will explore the use of hydrogel-forming microneedles (e.g. saccharide-based) coupled with single/dual bioelectrode systems for signal transduction. The mechanical, structural and sensor properties will be characterised and optimised. Toxicity and in-vivo assays will be performed on rodents with first device prototypes. The PhD. Work will be carried out at DTBS CEA Grenoble in collaboration with Dr. Gross from Dpt. Of Molecular Chemistry (UGA). The applicant should hold a Master degree in Chemistry, with focus on polymer chemistry, biomaterials, or electrochemistry.

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Cryogenic electronics to massively address silicon quantum bits

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Intégration Gestion d'Energie Capteurs et Actionneurs

SL-DRT-20-0675

xavier.jehl@cea.fr

(.pdf)

Research on quantum computing currently focuses on upscaling the number of qubits in order to reach useful calculation capabilities. The mature CMOS technology for circuits offers the opportunity to develop on-chip integration of CMOS spin-qubits together with classical electronics. Readout chips at sub-Kelvin temperatures form a key element in the massive addressing of a qubit matrix compared to nowadays solutions with cable-limited room-temperature instruments. Our previous studies on circuits made with the industrial 28-nm Fully Depleted Silicon on Insulator technology have demonstrated the operation of basic circuit elements down to temperatures as low as 20 mK with acceptable power dissipation. Using this toolbox of cryogenic circuits, the thesis concentrates on the design and operation of more complex cryogenic circuits in order to massively address CMOS-inspired qubits matrix at low temperatures. The ultimate goal is to readout 1000's of spin qubits in a line-column arrangement. The PhD student will explore alternative solutions for scalable readout such as the frequency multiplexing of electrometer sensors or of resonant oscillating circuits.

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3D reconstruction of nanoscale objects from stereoscopic electron microscope images

Département des Plateformes Technologiques (LETI)

Laboratoire

01-09-2020

SL-DRT-20-0679

aurelien.fay@cea.fr

(.pdf)

Keywords: Applied mathematics, Images treatment, Modeling, Inverse problem, Microelectronics. Robust, non-destructive and fast 3D metrology is a world-wide major challenge of microelectronics industry to better improve and control the nanotechnology processes [1]. CEA-LETI has state-of-the-art electron microscopes (SEM) for imaging objects from different points of view (stereoscopy). These equipments could be used in production to reconstruct the 3D topography of objects from reliable SEM imaging models and innovative algorithms. CEA-LETI already has strong expertise in this field [2, 3], and several industrial partners show a strong interest in the development of this technology. The objective of this thesis is to develop a 3D metrology from SEM images the most precise and robust as possible. For this, the PhD student will use the Computational Lithography group's theoretical and simulation resources to improve and develop new SEM imaging models. The scope of these models is broad, from the simulation of micrometric objects to nanoscale structures. The PhD student will train the SEM models on a collection of multi-stereo SEM images of patterns, whose 3D topographies will be measured via 3D reference metrology. He will then investigate different mathematical strategies of 3D reconstruction, allowing rapid convergence and quality. Eventually, 3D reconstruction will be applied to different industrial products of interest. Means: CLG python libraries, Collaborative development SVN, Continuous integration, HPC CPU/GPU, LETI technological platform. [1] B. Bunday, 7/5 nm logic manufacturing capabilities and requirements of metrology, SPIE 9780 (2018) [2] J. Bélissard et al., Limits of model-based CD-SEM metrology, Proc. SPIE 10775, 1077518 (2018) [3] C. Valade, Tilted beam SEM, 3D metrology for industry, Proc. SPIE 10959, 109590Y (2019)

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Continual learning for multimodal dataset

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Infrastructure et Ateliers Logiciels pour Puces

01-01-2020

SL-DRT-20-0686

marina.reyboz@cea.fr

(.pdf)

Like any embedded systems, edge AI (eAI) connects with its environment, via sensors and possibly actuators. It has to handle a variety of sensor inputs, in a multimodal environment. Even though several artificial neural networks (ANN) already exist, each of them handling one specific modality, there is still a huge challenge to build an ANN for multimodality. In the international state of the art, a spiking neural network classifying images and sound (MNIST dataset +sound) demonstrated better recongition rate and better robustness. The challenge is thus to find a generic approach, able to take State-of-the-Art modality-specific ANNs, and integrate them into a multimodal ANN. Another challenge for eAI is the capability to adapt to a new situation, e.g., a given user or a specific environment. An AI algorithm, even though it has been trained on a large global database, has to adapt. We mamed this property custumisation. The challenge follows: how an ANN, trained on a global database, could be fine-tuned for a specific use-case (e.g., a given user, a specific environment)? From an unimodal bio-inspired model of incremental Learning, the second part of the thesis will focus on coupling multimodal and custumisation aspects.

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Innovative mmw receivers architectures and circuits for resilient modulation schemes

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Architectures Intégrées Radiofréquences

01-10-2020

SL-DRT-20-0689

joseluis.gonzalezjimenez@cea.fr

(.pdf)

Existing telecommunication and data communication networks are evolving towards extremelly high capacity and data-rate connections that will require innovative transceiver architectures. For wireless data links, 5G and beyond 5G systems will be required in the next 5 to 10 years abel to provide 100Gb/s or higher data rates by efficiently using the wide spectrum available at millimeter-wave(mmW) frequencies. Traditionnal transceiver architecture that have been used in the past may result too power consuming or simply not performant enough to respond to this challenge. The LETI research institute has been conducting research during the lasts year in the field of innovative modulations schemes and transceiver architectures trying to respond to the abovementined high data-rate in wireless environements considering the limitation imposed by existing electronic devices required to build the transceivers. Currently some solutions have been proposed from a theoretical perspective that need to the be brought forward in order to find optimal implementation with state-of-art technologies for integrated circuits design and fabricatino. This thesis subjet is inscreibed in the continuations of those previous works and will explore the practical implementation of circuits based on innovative modulation schmemes and architectures for hihg-speed, large-bandwidn, imperfection resilient mmW receivers.

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Characterizations of electronic defects in perovskite crystals used for medical X-ray imaging

Département d'Optronique (LETI)

Laboratoire Architecture Systèmes Photoniques

01-09-2020

SL-DRT-20-0690

eric.grosdaillon@cea.fr

(.pdf)

The photonic systems architecture laboratory is part of the CEA LETI optronics department. We have a solid expertise in the development of new detection modules including a semiconductor or scintillator detector combined with readout electronics for X-ray or gamma imaging in the fields of medical imaging or security control. The objective of this thesis is to study the traps levels and densities in the bandgap of a new perovskite-based semiconductor material for direct X-ray detection developed for medical radiography. Its use as photoconductive devices in matrix imagers should improve the spatial resolution of images and increase the signal, thus reducing the dose given to the patient, or even providing access to new information on tissue composition. To reach this goal, the student, physicist and experimenter, will develop specific test bench to identify and characterize these electronic traps in the volume of crystals and at the interfaces of the devices. He will determine the nature of the defects of the thick crystalline layers developed by a doctoral student at CEA LITEN. The student will model the effect of these trap levels on the performance of the devices. In parallel, the student will study the origin of the current of darkness in perovskite devices. These results will be correlated with experimental measurements made by a doctoral student from CEA LETI. Finally, he will provide feedback on the development of crystals and devices in order to minimize the traps density and improve their overall performance.

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RTN entropy source extraction from RRAM for TRNG application

Département Systèmes (LETI)

Laboratoire Sécurité des Objets et des Systèmes Physiques

01-06-2020

SL-DRT-20-0693

florian.pebay@cea.fr

(.pdf)

As a consequence of the rapid development of the Internet of Things (IoT), where devices are massively interconnected, security breaches are discovered daily. The growing threat of physical attacks, on which connected objects are widely exposed, forces chipmakers to increase the security of their products. True Random Number Generators are the cornerstone of device security; they are required for running cryptographic algorithms and fully integrated into encryption engines. The security level of the system directly depends on the randomness of the bits generated. Furthermore, IoT chips are facing harsh constraints in terms of price and power consumption. In order to be integrated into these chips, TRNG must offer an efficient tradeoff between cost and security. In this perspective, TRNGs based on already integrated components, such as RRAM memories, is a promising lead.

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Fast Transcranial Acoustic Simulations and adaptive imaging for Personalized Dosimetry in Ultrasound Brain Therapy

Département Imagerie Simulation pour le Contrôle (LIST)

Laboratoire Simulation et Modélisation en Acoustique

01-10-2020

SL-DRT-20-0700

sylvain.chatillon@cea.fr

(.pdf)

The treatment of brain diseases remains very difficult, mainly because of the poor access of pharmacological agents to the brain due to the presence of the blood-brain barrier (BBB). Focusing low intensity ultrasound waves in the brain, combined with circulating microbubbles (ultrasound contrast agents), significantly increases the release of the drug into brain tissue, with an established therapeutic effect in many animal models. This permeabilization of the BBB is non-invasive, local and reversible provided that the intensity of the beam is well controlled through the skull because the implosion of microbubbles could lead to microhemorrhages. The structure and the complex geometry of the skull bone lead to a strong attenuation as well as specific phase shifts of the ultrasonic wave front during its crossing. The features of the focal task are severely impaired and the use of personalized simulation is unavoidable to ensure reproducible, controlled and safe therapy. These aberrations can be corrected by using a phased array ultrasonic probe of large aperture associated with delay laws calculated notably from ultrasonic wave propagation models, using a description of the morphology of the skull obtained by MRI or computed tomography (CT). In addition, the relative instability of the microbubbles makes it necessary to monitor their cavitation activity in order to be able to intervene in real time in the event of an acoustic signature announcing a risk of definitive lesion of the tissues (ultra-harmonic and broadband cavitation). Thus, in the previous NeuroSpin work, the use of a feedback loop based on passive cavitation detectors makes it possible to guarantee the safety of the macaque protocol. To go beyond the simple detection of these signals, it would be desirable to be able to map this activity through the skull using passive imaging with correction of aberration on reception. The objective of this hesis is to adapt and optimize the numerical simulation and imaging tools developed by CEA-LIST for Non Destructuve Testing (NDT) applications in order to: (i) predict and correct the pressure field obtained during a Transcranial Focused Ultrasound Therapy and (ii) significantly improve the quality of passive acoustic cavitation mapping during the procedure. This thesis, carried out in collaboration between the S. Chatillon team at the DRT / LIST and that of B. Larrat at the DRF / JOLIOT / NeuroSpin, will comprise the following three stages: - Validation of the propagation model on samples of human skulls. - Optimization of the trajectory to reach a target point to be treated (inverse problem). - Transcranial imaging of microbubble cavitation activity during the procedure

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Fine chemical nanocaractisation of GaN structures for nano and opto-electronic applications

Département des Plateformes Technologiques (LETI)

Autre laboratoire

01-10-2020

SL-DRT-20-0701

marc.veillerot@cea.fr

(.pdf)

The use of III-N materials is widespread, not only for the electronic power components but also for new low consumption lighting technologies based on µLEDs. However, a better control of the material properties (composition & doping) as well as the quality of critical interfaces is necessary to increase the electrical performance of the components. XPS and SIMS chemical characterization techniques are already being used to help improving these structures. However, both of these techniques need to be developed and combined to produce the reliable information needed to optimize materials and fabrication processes for GaN-based devices. This PhD subject is built on two lines of work. The first, of immediate industrial interest, is the fine combined characterization of surfaces and interfaces for thin planar stacks (a few nm) of AlGaN / GaN and oxide / GaN type. The development of specific methodologies is required such as low energy SIMS for high depth resolution and high energy XPS for analysing buried interfaces. The second, more prospective, is the characterization of three-dimensional structures integrated into the final devices of micron size. For this purpose, we will focus on variants of XPS and SIMS techniques with higher lateral resolution. This part of the work, carried out in collaboration with academic and / or industrial partners, will make it possible to anticipate the characterization capabilities of future devices.

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Colorimetric detection of organophosphorus based pesticides: From organic synthesis to colorimetric paper detector

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire Synthèse et Intégration des Nanomatériaux

01-09-2020

SL-DRT-20-0714

sebastien.penlou@cea.fr

(.pdf)

This PhD thesis deals with the design and synthesis of chromogenic dyes and the processing method needed for the development of chromogenic detector of organophosphorus pesticides. A chromogenic dye is a molecule that changes color when it is in the presence of a target molecule. At the CEA Grenoble, the LSIN laboratory has developed an expertise around the colorimetric detection, via the screening of a chemical library of commercial chromogenic dyes. We identified commercial reactive structures. The aim of this thesis is to synthesize more reactive structural analogues with controlled color change. It is proposed to validate the actual color changes on organophosphorus pesticides. Finally, the study of the reactivity of chromogenic dyes versus organophosphorus pesticides (NMR, FTIR, UV-vis-NIR, mass spectrometry, ...) should allow us to better understand their reactivity and propose a reaction mechanism explaining the color changes observed. A prototype of a low-cost organophosphorus pesticide colorimetric detector will be developed at the end of the thesis.

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Surface physico-chemical properties modification by multi-scale nano-patterning

Département des Plateformes Technologiques (LETI)

Laboratoire

01-10-2020

SL-DRT-20-0720

maxime.argoud@lcea.fr

(.pdf)

Over the past 20 years, surface patterning methods have been developed in the field of advanced lithography for microelectronics. These breakthrough techniques, such as directed self-assembly of block copolymers or nano-imprint lithography, appeared to be a credible low-cost alternative to traditional optical lithography methods. Many studies have demonstrated and confirmed this potential, up to the 300mm wafer scale, however these technologies have not been tranferred for CMOS applications, particularly because of the defectivity and the industrialization of the extreme UV lithography. The maturity of the various processes and materials developed, as well as the associated global understanding, now offers many opportunities for applications for which defectivity is not critical. In particular, the modification of the surface physico-chemical properties by nano-patterning, on several scales, using of the relatively low-cost patterning techniques previously mentioned, could address many application domains (optical properties, biotechnologies, self-assembly of chips ...). The thesis work will focus on the modification of surface physico-chemical properties by nano-patterning. The surface patterning will be achieved by advanced patterning technologies such as self-assembly of block copolymers, over a wide range of periods (from 20 to 200nm), directed or not, and also by nano-imprint lithography. A working axis will concern the implementation, and the associated understanding, of these patterning techniques. Various thin layers or bulk materials may be structured, and the physico-chemical properties obtained will be finely characterized. An original axis of the work will also focus on the multi-scale aspect of this pattering, from the point of view of patterning itself over a wide range of dimensions (from a few nm to several hundred nm), or from the dimension of the modified surfaces (from a few hundred nm² to several tens of cm²). Some properties can be applied to various application domains (optics, biotechnologies, chip self-assembly ...).

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Study of cathode materials for lithium-ion batteries by experimental and theoretical soft and hard X-ray photo-emission spectroscopy

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Nanocaractérisation et Nanosécurité

01-09-2020

SL-DRT-20-0722

anass.benayad@cea.fr

(.pdf)

Photoemission spectroscopy (X-ray, XPS, or ultraviolet, UPS) is a direct probe of the electronic structure of materials and redox processes involved in batteries at the atomic scale. However, it is limited by the extreme surface sensitivity of the material's, with a typical photoelectron path length of a few nanometers to the energies usually available in the laboratory . In addition, spectrum interpretation requires the ability to accurately model this electronic structure, which is particularly delicate in the case of cathode materials that contain transition metals and are used in a wide range of lithium compositions. Indeed, the electronic structure of these materials has electronic correlation effects whose character depends in particular on the filling of the orbitals "d". In this thesis, we propose to use these limitations to our advantage to explore the electronic surface structure including the solid electrolyte interphase (SEI), and the core of the active cathode particle. To do this, we will take advantage of the first hard X-ray laboratory spectrometer in France (HAXPES), which will be installed at the NanoCharacterization Platform (NCPF) in spring 2020, and will probe materials up to about 20 nanometers , . The comparison between the XPS and HAXPES spectra, during battery operation (in operando) and/or post-mortem in the same area, will allow decoupling of the surface and core spectra for different chemical compositions and at different stages of the battery life cycle. The interpretation of the photo-emission spectra will be done by direct comparison with ab initio calculations combining density functional theory (DFT) with dynamic mean field theory (DMFT). This coupling will make it possible both to go beyond the usual techniques based on cluster models, which do not take into account metal shielding, and to validate the quality of theoretical predictions on the effects of electronic correlation (effective mass, potential transfer of spectral weight to Hubbard bands). The thesis will include an instrumental (in particular, calibration of effective surfaces on model systems) and theoretical (prediction of core photo-emission spectra based on DFT+DMFT calculations) development, then will compare the performance and ageing of different cathode materials (LiCoO2, NMC of different compositions) in combination with liquid and solid electrolytes and a Li metal anode. The candidate will be hosted in the L2N laboratories of the DTNM and LMP of the DEHT to conduct his work.

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Innovative haptic interface

Département Composants Silicium (LETI)

Labo Composants Micro-actuateurs

01-09-2020

SL-DRT-20-0724

fabrice.casset@cea.fr

(.pdf)

A haptic interface allows to the user to interact with its environment by the sense of touch. It can be used for example to give complex information in harsh, noisy or low visibility environment. Today, demonstrators provide haptic effects essentially on glass screen. We propose to develop innovative haptic solutions to generate complex effects on curved surfaces, conformable, and potentially in various materials such as metal, plastic? The objective of the candidate will be to design, build and characterize haptic interfaces. A reflection will be conducted on the different possibilities to integrate this haptic function on various substrates. To do this, he will develop analytical models and use finite element method (COMSOL). Supervised by CEA experts on the subject, he will propose the most adapted technology (thin-film actuators or bulk piezoceramics) to integrate piezoelectric actuators able to generate the haptic effect on curved surfaces, conformable, ideally flexible. Finally, a reflection on the global system will be necessary in order to propose an innovative and complex haptic demonstrator integrating different functions such as finger position detection, actuation and driving mechanisms.

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Multi-scale modelling approach of a steam storage with Phase Change Materials integrated into a thermal process

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire Stockage Thermique

01-10-2020

SL-DRT-20-0726

pierre.garcia@cea.fr

(.pdf)

Steam storage allows industrial processes and power plants to be more flexible, more reliable, and more stable by time-shifting steam production from steam use. The use of Phase Change Materials (PCM) offers numerous advantages, like steam discharge at constant pressure, a high energy density, and a significant reduction of the pressurized volume. At CEA, a shell-and-tubes PCM storage technology is being studied for several years, through various experimental facilities and modelling activities. A recent work allowed to develop a multi-scale methodology based upon Computational Fluid Dynamics numeric simulations (modelling the PCM melting front and natural convection in a complex geometry) to feed a component model. The aim of the PhD thesis is on one hand to check this predictive approach on new experimental results, and on the other hand to generalize it on other storage geometries, in order to validate its use for the design of industrial-scale storage systems. Finally, another objective is to integrate the component model derived from the multi-scale approach into a system model so as to study the interactions between the storage and its environment and thus to optimize its operation to meet the process' needs.

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Development of MOFs for the detection, adsorption and destruction of toxic gas

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des Eco-procédés et EnVironnement

01-09-2020

SL-DRT-20-0736

arthur.roussey@cea.fr

(.pdf)

This PhD thesis focuses on the development of novels Metal Organic Frameworks (MOFs) for the adsorption and destruction of toxic chemicals such as H2S or organophosphorus based pesticides. MOFs are a class material with very high specific surface area composed of metallic ions or clusters coordinated with organic ligands. As a wide variety of metals and ligands can be used, innovative materials can be synthesized to obtain specific physical and chemical properties. During the thesis, using molecular engineering, the candidate will synthesize and/or functionalize MOFs to enhance their adsorption capacity and selectivity towards the target chemicals. Mechanistic studies of adsorption or chemisorption will be performed by adsorption capacities and selectivity measurement in conditions representatives of the applications. Materials structure and target/material interactions will be finely characterized using the wide range of available technics (XRD, XPS, FTIR, UV-Vis-NIR, solid-state NMR, ?). The integration of chromogenic ligand will also be investigated to allow direct colorimetric detection of the target chemicals.

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Study of integraiton of 2D materials in RF devices

Département Composants Silicium (LETI)

Laboratoire Intégration et Transfert de Film

01-09-2020

SL-DRT-20-0739

lucie.levan-jodin@cea.fr

(.pdf)

Since the discovery of graphene (Nobel pice 2010 by Andre Geim), the enthusiasm for 2D materials has grown steadily. In fact, these materials have very remarquable properties that make them serious candidates to create new generations of high-performance electronic or optoelectronic devices, miniaturization, flexible devices and low energy consumption. The aim of the thesis is to develop new 2D-based radio frequency (RF) switch concepts for future wireless telecommunications systems. The work is multidisciplinary and will be carried out in close collaboration between two CEA institutes: IRIG will bring its expertise around the growth and characterization of the electrical properties of 2D materials and the LETI will bring its expertise on the integration of thin layers in devices and on design of RF switches. The Phd candidate will seek to identify the key points of this type of device and to improve our understanding of the mechanisms involved, especially when switching. It will develop the methods of transfer of the material into the device and seek to optimize the electrical contact between the 2D materials and the metal electrodes. Finally, it will develop the technological integration processes of switches in planar or vertical configurations, seeking to ensure compatibility with integration on Si for microelectronics.

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Resistance level modulation in PCM memory for neuromorphic applications

Département Composants Silicium (LETI)

Laboratoire de Caractérisation et Test Electrique

01-03-2020

SL-DRT-20-0740

carlo.Cagli@cea.fr

(.pdf)

Since the last 50 years, the processors are based on the von Neumann architecture and the progress in the integration on a very large scale made it possible to realize this computational architecture on a suitable technological substrate. However, today the miniaturization of electronic components is no longer sufficient to increase performance and reduce the power consumption of conventional architectures. In addition new applications, first of all the artificial intelligence, requires completely new paradighms and calculation approaches. New computational architectures inspired by biology have recently been proposed to overcome these difficulties. The main difference between a neuromorphic circuit and a classical architecture is the memory organization: networks of biological neurons are characterized by co-localization of memory (synapses) and computing centers (neurons). PCM memories are see as strong candidates for emulation of synaptic behavior but the ability to modulate their resistance level is still a challenge. This is a key point to enable PCM cell as synaptic component. This work proposal will start with a characterization phase where the ability of PCM to be modulated in different resistance levels will be scrutinized. The collected data will feed a PCM multilevel model, which is essencial to enable new circuit architecture. In a final stage, innovative circuit can be proposed, based on PCM technology, as proof of concept for neurorphic applications.

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Advanced chemical analysis of organic light emitting diodes

Département des Plateformes Technologiques (LETI)

Laboratoire Analyses de Surfaces et Interfaces

01-10-2020

SL-DRT-20-0748

jean-paul.barnes@cea.fr

(.pdf)

The nanocharacterisation platform has recently installed several advanced characterisation techniques : a new time of flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectrometer (XPS). Both instruments are equipped with a novel argon cluster ion source that allows damage free analysis of organic layers such as those found in organic light emitting diodes (OLEDs). The lifetime of OLEDs may be limited by the electrical or environmental ageing or the organic layers contained in the device. For the development of OLEDs it is important to be able to characterise the degradation of organic layers. The objective of this PhD project is to develop the advanced TOF-SIMS and XPS protocols needed to quantify and understand the degradation of the layers. The development of specific sample preparation methods will be carried out in order to be able to analyse the same area of the sample using several different techniques. The candidate will work closely with the team at the CEA-LETI making the OLED devices and materials and the instrument suppliers.

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Critical buried interfaces in imaging devices studied by novel hard X-ray photoelectron spectroscopy techniques

Département des Plateformes Technologiques (LETI)

Laboratoire Analyses de Surfaces et Interfaces

01-10-2020

SL-DRT-20-0750

orenault@cea.fr

(.pdf)

The development of advanced generic technologies such as imagers or memories requires a fine understanding on the properties of critical interfaces. To this end, implementing cutting-edge nanocharacterisation methods and instrumentation is of utmost importance. Here, we address the implementation of a novel X-ray photoelectron spectroscopy technique employing hard X-rays (HAXPES: HArd X-ray Photoelectron Spectroscopy) delivered by a Chromium source in a new kind of photoemission spectrometer recently installed at the Minatec PlatForm For Nanocharacterization, CEA-Grenoble. With this technique, the probing depth of conventional photoelectron spectroscopy is enhanced by a factor of 3-5, enabling to get access to deeply buried interfaces localized 20-50 nm below the surface, which is a typical situation in devices. The thesis work is organized around two aspects : a first one deals with the chemical state analysis of critical buried interfaces in imager devices and other thecnologies developped at ST Microelectronics. The second aspect is focused on interface electronics and in-depth potential distribution, especially targetting the determination of valence band offsets.

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Transparent piezoelectric actuators for haptic

Département Composants Silicium (LETI)

Labo Composants Micro-actuateurs

01-10-2020

SL-DRT-20-0756

gwenael.le-rhun@cea.fr

(.pdf)

The haptic technology (science of touch) is in full rise and attracts more and more interest from industrials in the fields of telephony or automotive. Piezoelectric actuators are used to generate vibrations on a tactile surface to produce a haptic feedback, thus facilitating (or augmenting!) interactions between the user and his environment. Some tactile surfaces, such as screen, dashboard or window, would ideally require the use of transparent actuators. However, thin film piezoelectric actuators are deposited on a silicon substrate and incorporate non-transparent layers (electrodes, etc.). Strong technological constraints, such as the crystallization temperature of the piezoelectric material (around 700 °C for the PZT), make the thin film deposition of transparent piezoelectric stacks on glass particularly complex, or impossible. LETI has recently developed an innovative technology for transferring one or more layers, for example PZT, from a silicon growth substrate to a host substrate such as glass (several patents). The objective of this thesis will be to design and realize transparent piezoelectric actuators on glass substrate for a haptic application. A state of the art on the subject will make it possible to establish the targeted specifications for the chosen device. Based on the knowledge and expertise available at LETI, the PhD student will work on the integration of materials (piezoelectric, electrodes, etc ...) allowing in particular obtaining a functional stack with the required transparency, as well as on the design and the realization of the actuators and their characterizations.

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Microstructure control of additive manufacturing parts by generation and detection of ultrasound by laser

Département Imagerie Simulation pour le Contrôle (LIST)

Laboratoire Instrumentation et Capteurs

01-01-2020

SL-DRT-20-0757

jerome.laurent2@cea.fr

(.pdf)

The metal additive manufacturing (AM) processes show a great potential still growing, and those in very varied applications fields. However, existing systems have limitations, in particular on the ability to adapt the microstructures and to detect online the melting defects [1]. To overcome these limitations, it is necessary to develop new manufacturing strategies that could make it possible to adapt the solidification conditions as well as online non-destructive testing (NDT) inspection methods. Direct energy deposition (DED) or selective laser melting (SLM) processes use metallic powder and a locally concentrated energy source, which generates strong thermal gradients, which most often lead to highly oriented microstructures and relatively rough surfaces, both making NDT inspection and physical interpretations more tricky. The microstructures produced are out of thermodynamic equilibrium and possess coarse grains structure; they are characterized by the entanglement of columnar and equiaxed grains. This type of microstructure influences significantly the mechanical behavior and elastic waves propagation; the size distribution of heterogeneities are close to the acoustic wavelengths, having for effect the attenuation and scattering of elastic waves. One of the major challenges in AM is to reduce/prevent the formation of columnar grains during manufacturing, as their presence within the microstructure is the most unfavorable for the use properties. By controlling the thermal conditions during the solidification/crystallization (cooling rate, temperature gradients), it is a priori possible to favorably induce the formation of equiaxed grains. It is also known that, by insonification of the molten metal with high intensity ultrasound, it is possible to perform a ?grain refinement-like?, or also to generate other effects (cavitation, flow, mixing, spraying, dislocation, scattering and phase transformation [2]). Indeed, when an elastic vibration is applied directly to molten metal, it would be possible to control-like the solidified grain structure, i.e. to change locally the direction of growth and morphology of the microstructure during the solidification phase. Therby perturbating the solidification conditions, then, it is conceivable to cause the formation of equiaxial grains, and, potentially, the number of flaws (microporosities, cracks). This observation sets the objective of this thesis, which aims to shape more optimally the AM microstructures by vibrating the melting pool and to conduct either offline or online monitoring by ultrasonic-laser (LU) technique. On the one hand, the work, in the CEA-DEN-LISL Lab. [3], will consist of controlling the microstructural evolution of AM parts by contactless vibration of the melting pool. Thus, it will seek to modify the dynamics of the melt, for example, by destabilizing the dendritic growth in the solidification front due to elastic waves generation with a continuous-wave modulated or pulsed laser source. The control parameters will be assessed in laboratory conditions using an existing experimental prototype, which will be improve by adding several other instruments (fast/thermal/Schlieren cameras, pyrometer) to generate ?enhanced microstructures? and by improving the coaxial manufacturing nozzle. On the other hand, the work in the CEA-DRT-LIST Lab., will consist to inspect online AM samples by employing a LU method. Thus, it will seek to generate and detect ultrasound by laser in the melt, to monitored, for example, the evolution of solidification front, keyhole outbreak, optical penetration evolution, and so on, by measuring acoustic precursors [4]. Ultrasonic characterization measurements, under laboratory conditions, will also be carried out in order to determine the elastic properties by LU [5], whether using surface waves (Rayleigh) or zero-group velocity modes (local Poisson's ratio, anisotropy, thickness), and other NDT methods available from the LIST lab., which can then be compared to EBSD (homogenization method) and metallurgical cuts. FDTD or Finite Elements simulations of ultrasound in these rough and heterogeneous media will also be considered. References: [1] Zhao et al, Phys. Rev. X, 9, 02052, (2019), Wolff et al, Sci. Rep., 9, 962, (2019), Martin et al., Nat. Com., 10, 1987, (2019), Wei, Mazumder & DebRoy, Sci. Rep., 5, 16446, (2015). [2] G. I. Eskin & D. G. Eskin, ?Ultrasonic melt treatment of light alloy melts', 2nd edn, Boca Raton, FL, CRC Press, (2014), M. C. Flemings, ?Solidification processing', McGraw-HilI press, (1974), T.T. Roehling et al., Acta Materialia 128, 197, (2017), M.J. Matthews et al., Optics Express 25, 11788, (2017). [3] P. Aubry et al., J. Laser Appl., 29(2), (2017) [4] Walter & Telschow, QNDE, 15, (1996), Walter, Telschow & Haun, Proc COM, (1999), Carlson and Johnson, WJ, (1998), He, Wu, Li & Hao, Appl. Phys. Lett., 89, (2006). [5] Clorennec, Prada & Royer, Murray, Appl. Phys. Lett., 89, (2006), Laurent, Royer & Prada, Wave Motion 51(6), (2014) Laurent, Royer, Hussain, Ahmad & Prada, J. Acoust. Soc. Am. 137(6), (2015).

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Integration in tandem devices of passivated contacts PV cells : Towards a multifunctional and universal interface technology

Département des Technologies Solaires (LITEN)

Laboratoire HoMoJonction

01-10-2020

SL-DRT-20-0758

thibaut.desrues@cea.fr

(.pdf)

This project aims to develop cristalline (c-Si) silicon PV cell technolologies with passivated contacts for tandem devices applications. To overcome conventional single junction cells limitations, one interesting research topic is about tandem structures which allow conversion efficiencies above 30%. For these tandem devices, it is necessary to optimise c-Si bottom cells fabrication processes to enhance the complementarity between both devices (Top and Bottom cells). The main goal of the PhD is to obtain universal c-Si Bottom cells adapted for all top cells technologies (Perovskite, CGS, III/V,...). These c-Si bottom cells will rely on the poly-Si/SiOx technology which allow to avoid the use of transparent conductive oxide (TCO)layers and also to obtain a great temperature stability of the devices. This last feature enables high temperature steps for the topcell fabrication processes. This project will consist in: 1/ Develop thin films and stacks optimized for bottom c-Si cells used in tandem architecture 2/ Characterize electrical and optical properties of the developed structures 3/ Integrate these structures into a tandem device using potentially different topcell technologies

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Multiscale modeling of lithium transport in solid and hybrid Li-ion electrolytes and their interfaces

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Modélisation multi-échelle et suivi Performance

01-10-2020

SL-DRT-20-0762

natalio.mingo@cea.fr

(.pdf)

Energy storage is an essential component of a sustainable energy infrastructure based on intermitted renewable sources, such as photovoltaics or windmills. Amongst storage technologies, lithium-ion batteries are possibly the main current option for private electric vehicles. But the adoption of electric vehicles will be greatly facilitated if one can solve important challenges of the current generation-3 Li-ion batteries: insufficient energy density and recharge speed, aging, and safety issues. The upcoming generation-4, based on Li-metal anodes and solid-state (SS) electrolytes, is expected to solve many of these issues: Li-metal SS batteries' theoretical energy densities approach those of petrol2; solid electrolytes can be made very thin to further reduce battery size, and they have been shown to improve safety by decreasing dendrite formation; addition of nanoparticles has been found to improve ion mobility in the electrolyte, enhancing recharge speeds. However, the physical mechanisms responsible for solid-electrolyte/Li-metal system's advantageous qualities are still very poorly understood at the atomic level. To make generation-4 batteries a reality, it is essential to elucidate and quantify these mechanisms. Predictive atomistic simulations, as proposed in this thesis, may play a big role in this respect.

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Deep Reinforcement Learning Agents Revealing Uncertainties in Blockchain Systems

Département Ingénierie Logiciels et Systèmes (LIST)

Lab.systèmes d'information de confiance, intelligents et auto-organisants

01-09-2020

SL-DRT-20-0772

onder.gurcan@cea.fr

(.pdf)

Since its genesis in late 2008, Bitcoin had a rapid growth in terms of participation, number of transactions and market value. This success is mostly due to innovative use of existing technologies for building a trusted ledger called blockchain. A blockchain system allows its participants (agents) to collectively build a distributed economic, social and technical system where anyone can join (or leave) and perform transactions in-between without needing to trust each other, having a trusted third party and having a global view of the system. It does so by maintaining a public, immutable and ordered log of transactions, which provides an auditable trusted ledger accessible by anyone. However, blockchain systems are environments that are too complex for humans to pre-determine the correct actions using hand-designed solutions. Furthermore, the agents performing in these systems have limited observability, and the state and parameter spaces are vast and changing dynamically. Consequently, agents that can learn to tackle such complex real-world uncertain domains are needed. Based on this observation, , the objective of this thesis is to investigate the uncertain constraints of blockchain systems and to propose a deep reinforcement learning decision-making approach based for all agents like that agents will learn to cooperate in a multi-agent setting in blockchain systems and continuously learn the uncertain constraints.

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Design and fabrication of GeSn based components for environmental detection

Département d'Optronique (LETI)

Laboratoire des Capteurs Optiques

01-10-2020

SL-DRT-20-0776

vincent.reboud@cea.fr

(.pdf)

Integrated laser sources compatible with microelectronic technologies is currently one of the main challenges for silicon photonics. CEA is part of the few laboratory that demonstrated mid-infrared optically pumped lasing in GeSn micro-cavities. Our aim is to go towards lasing at room temperature in fully relaxed or tensile-strained heterostructures and quantum wells made of germanium tin alloys. Defect reduction in the gain zone and carrier confinement optimisation in order to reach high gain is the major issue of this study. We would indeed like to minimize the lasing threshold and obtain continuous emission lasers. We also target a decrease the concentration of tin in germanium by focusing strain to further increase the crystalline quality of quantum wells and heterostructures and still reach direct band gap in the structures. Objectives of the research will be (i) to reduce crystalline defects in the gain zone, (ii) to find efficient geometries to confine electrons and holes, (iii) to apply tensile strain to germanium tin crystals, (iv) to evaluate the electrical gain dependence with different strains and doping levels, (v) to characterise the optoelectronic properties of epitaxial materials, (vi) to design and fabricate laser cavities with strong optical confinement in order to reach tunable continuous germanium lasers compatible with the current microelectronic technologies for environmental detection.

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Asymetrical pattern manufacturing for light managment

Département des Plateformes Technologiques (LETI)

Laboratoire Gravure

01-09-2020

SL-DRT-20-0781

slandis@cea.fr

(.pdf)

The introduction of augmented reality, especially on portable optical systems such as eyeglasses, requires the manufacture of specific diffraction gratings to generate immersive images in a very small volume. One of their specificities is that they have an asymmetrical geometry (inclined sidewalls) making them particularly complicated to manufacture with the standard processes used for micro systems and microelectronics.

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Transfer Learning and Optimal Transport applied to additive manufacturing process driving

Département Métrologie Instrumentation et Information (LIST)

Laboratoire Science des Données et de la Décision

01-10-2020

SL-DRT-20-0792

fred-maurice.ngole-mboula@cea.fr

(.pdf)

This PhD thesis aims at exploring possible contributions of optimal transportation field to transfer learning through the following directions: - building a knowledge transferability criterion between a source and a target task based on the regularity of the transportation plan between the source and the target data distributions; - integrating priors on the tasks similarity through the transportation ground metric; - applying Wasserstein barycenter to multi-task learning problems. These works might find multiple practical use-cases of interest in the lab, including additive manufacturing. A more detailed presentation of this PhD thesis subject can be found via the following link: https://drive.google.com/file/d/1TmoIYeK9RKRWV7aHFGeqY48tpobuBJeB/view?usp=sharing

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Thermal optimization of Phase Change memoires: study of innovative PCM and dielectric materials for their integration in advanced PCM cells

Département Composants Silicium (LETI)

Laboratoire de Composants Mémoires

01-09-2020

SL-DRT-20-0796

marie-claire.cyrille@cea.fr

(.pdf)

Phase Change memories are now recognized as a ?mature non volatile memory technology'. They are now proposed by ST Micro for their microcontrolleurs for automotive applications. The chalcogenide (GeSbTe) material used was chosen for its high thermal stability compatible with automotive application but it is slow to crystallize hence leads to high power consumption while programming devices. Thermal optimization of the PCM cell is THE way to enable the reduction of programming currents. The goal of this thesis is to characterize the thermal properties of the chalcogenide and dielectric materials used in the integration of PCM cells and to proposer innovative solutions towards thermal optimization. The thesis will be in collaboration the I2M institute of Bordeaux University which is well recognized for the development of radiometric techniques for thermal conductivity characterization on film films: modulated photothermal radiometry (MPTR); periodic pulse radiometry (PPTR); modulated scanning thermal microscopy (SThM).

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Pure phase optical modulation based on Pockels effect in strained silicon

Département d'Optronique (LETI)

Laboratoire d'Intégration Photonique sur Silicium

01-09-2020

SL-DRT-20-0798

leopold.virot@cea.fr

(.pdf)

The use of silicon photonics has been identified as a mean to overcome interconnect limitations and efficiency, but also as a versatile platform able to address the new problematics encountered in Lidar and quantum photonics applications. However, the possibility to have high-speed pure phase optical modulation has not been addressed yet on this platform. Silicon, as a centrosymmetric material does not exhibits second order non-linearities. Nevertheless, it has been theoretically and experimentally demonstrated that by applying a mechanical strain, its centrosymmetric can be broken, leading to the exhibition of second order non-linearities. Recent proofs of concept have been demonstrated with a modulation at 20GHz based on the use of silicon nitride stress layers deposited by PECVD on top of silicon. The objectives of the PhD will be to enhance the Pockels effect in silicon waveguides by a factor of 10 to 100, in order to reach performances close to LiNbO3. This research activity will include : Fine theoretical study of the involved processes and how to control them, and also electro-optic simulations in order to evaluate the performances of such devices and optimize the overlap between the strain field and the optical mode in the waveguide; The design and fabrication of optical phase modulators optimized to maximize the Pockels effect in the waveguide; DC and RF characterization of optoelectronics devices bas on second order non-linearities.

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Simulation of PEMFC manufacturing irregularities

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Modélisation multi-échelle et suivi Performance

01-10-2020

SL-DRT-20-0799

pascal.schott@cea.fr

(.pdf)

The cost of PEMFC remains the bottleneck for moving the technology to the market place. Membrane electrode assembly (MEA) manufacturing must be cost-effective and assure high quality. In-line diagnostic tools have been developed by the NREL (National Renewable Energy Laboratory), that monitor the quality of electrode coatings. They have been successfully used to detect a variety of electrode coating irregularities in R2R (Roll-to-Roll) manufactured material sets. However, limited understanding exists regarding if and to what extent electrode irregularities impact PEMFC performance and lifetime. The objective of this PhD thesis, is to improve the understanding of and predict lifetime of MEA that contain material irregularities, such as for example membrane holes or cracks, and electrode voids or thick spots. CEA's multi-physics and multi-scale modeling approach will be used, coupled with a statistical analysis of experimental data provided by or collected at NREL. The following focus areas will be addressed: ? Impact of the defects (pinholes, catalyst degradation, non uniform distribution) on performance (potential mixt) ? Impact of the defects (particle size distribution, membrane thinning) on degradation ? Probabilistic failure prediction based on sensitivity analyses of mechanistic model and experimental data The thesis will be located at CEA Grenoble France, with several 3 months missions at NREL, Colorado, USA.

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Development of an alkaline electrolyzer simulator with anion exchange polymer membrane.

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Modélisation multi-échelle et suivi Performance

01-10-2020

SL-DRT-20-0801

gserre@cea.fr

(.pdf)

Alkaline systems with anion exchange polymer membrane (AEM) are of increasing interest because they have the cumulative advantages of alkaline systems and PEM (proton exchange membrane) systems without their disadvantages: no need for platinum as a catalyst, polymer electrolyte instead of diaphragm, no need for KOH solution, no problem induced by acidity. These systems however require a significant research effort before reaching the industrial maturity. To address this theme of alkaline systems AEM, it is proposed to develop a simulator of normal and degraded operations. This tool will be the receptacle of available physicochemical models and coming ones for this technology. In practice, the lab already has a code under Matlab / Simulink for electrolyzer PEM. This code will have to be adapted to AEM electrolyzer by changing the physicochemical performance models (normal operation) and adding those for degradation. This will require analyzing the existing models in the literature and developing those that do not exist or are insufficient, using the results of experiments that will take place at the same time in a nearby laboratory. This thesis will aim at developing the code, first so that it is able to simulate the performances under different operating conditions, then that it can simulate the degradation of these performances over time according to the parameters influencing different types of degradation (membrane ...). The candidate must have skills in modeling and numerical simulation, as well as physico-chemistry and know how to interact with the people who will be doing the tests used to develop / validate new models.

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Remotely powered and searchable sensors

Département Composants Silicium (LETI)

Laboratoire Composants Micro-Capteurs

01-09-2020

SL-DRT-20-0803

patrice.rey@cea.fr

(.pdf)

The need for sensors that can be remotely interrogated makes it possible to envisage new applications both in aeronautics (aircraft wing monitoring, turbine blades), energy (measurements on rotating devices), civil engineering (structural monitoring) consumer applications such as screens, health (medical patch) and also in the fields of security and defense. For these sectors, we can emphasize the interest of this type of remotely powered and searchable sensors, in all situations where a sensor must be placed in an inaccessible location, where the sensor can be buried, in harsch environment for electronics or batteries (high temperature, explosive atmosphere, etc ...), where it can not be electrically connected to the outside (rotating machine, cramped space, etc ...). The "M&NEMS" sensor technology developed by CEA-LETI can meet this need for extreme miniaturization, ultra-low consumption, high performance and low cost. In addition, CEA-LETI is also working on passive sensors with electromagnetic transduction integrating a miniature antenna, sensors that have a very strong interest to be read remotely by an interrogating antenna. This type of sensor coupled to an antenna without an electronic circuit can also enable an increase of the interrogation distance between the reader and the remote-powered sensor, compared to RFID tags that require energy to wake up the circuit. The challenge is to couple and integrate these silicon sensors with an antenna architecture (co-design). The work will consist of designing and manufacturing antenna-sensor systems by jointly studying each of the two components in order to optimize the coupling in remote power and remote transmission. This will require close interaction between the sensor design and the antenna. Several types of sensors operating in static mode or in resonant mode can be studied. To carry out this multidisciplinary work, the PhD student will rely on the expertise and resources of several CEA-LETI laboratories: the Sensors Laboratory (LCMC), the Tests and Reliability Laboratory (LCFC) of the Silicon Components Department and also on the Antenna, Propagation and Inductive Coupling Laboratory (LAPCI) of the Systems Department as well as on a technological platform for the sensor manufacturing. It will be able to collaborate with other PhD students involved in this theme, especially for the design part of the adapted antenna

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Development of an innovative method for identify the thermomechanical properties of thin films. Application to the design and manufacture of a microelectronic device

Département des Plateformes Technologiques (LETI)

Laboratoire Propriétés des Matériaux et Structures

01-10-2020

SL-DRT-20-0804

lionel.vignoud@cea.fr

(.pdf)

Frame and context: the design and manufacture of microelectronic devices require knowledge the thermomechanical properties evolution of the materials that make up the components. Based on experimental measurements, data processing and simulation tools (MATLAB), we propose to develop an innovative method for identifying the module E and the coefficient of thermal expansion of thin layers. We will apply this work to the manufacture of a microelectronic device. Work required: the student in engineering school or master's degree in mechanics and/or materials, will be trained and must master both the experimental measurement techniques used to characterize the materials (in a clean room environment) and the analysis and calculation tools that we will use in this study. He will work on the design, manufacture and reliability of microelectronic devices with different teams from LETI and ST Microelectronics. The objective is to limit component strain, optimize manufacturing steps and finally, make devices more reliable.

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µ-LEDs based on nitride semiconductors in semi-polar orientation

Département d'Optronique (LETI)

Laboratoire des Composants Emissifs

01-09-2020

SL-DRT-20-0813

fabian.rol@cea.fr

(.pdf)

GaN-based microLEDs are on the verge to revolutionize the display world, on one hand providing ultra-high brightness microdisplays for augmented reality applications, on the other hand paving the way for large area displays with unrivaled image quality. Blue-emitting LEDs based on nitride semiconductors exhibit good efficiency, however it is not the case for green and red ones, for which external quantum efficiency does not exceed a few percent. The main reasons are related to the existing growth techniques, which induce high polarization field and high level of crystalline defects. We propose a novel GaN growth technique which will allow to fabricate microleds with improved efficiency both in blue, green and red. The objective of the thesis is first to investigate and improve the growth conditions in order to obtain GaN Led epilayers for blue, green and red emission with better crystalline quality. The objective is also to fabricate and characterize GaN microleds in order to verify the improvement at the device level.

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Antimicrobial functionalization of nanostructures by initiated Chemical Vapor Deposition

Département Microtechnologies pour la Biologie et la Santé (LETI)

Laboratoire Chimie, Capteurs et Biomatériaux

01-10-2020

SL-DRT-20-0814

guillaume.nonglaton@cea.fr

(.pdf)

The production of antimicrobial and antibiofouling surfaces without antibiotics or nanoparticles is still a challenge despite the needs of a growing number of applications, particularly in the hospital field and more specifically for implanted medical devices. The number of patients infected each year with nosocomial diseases is still too high and infections related to implanted medical devices remain an unresolved problem. The limit of current solutions is their very short lifetime and their rapid fouling by biofilm generation. The scientific community increasingly studied bio-inspired coatings made of polymers with antimicrobial, antibiofouling or switchable functions. However, these coatings are still difficult to achieve by green chemistry on structured surfaces using conventional methods. Initiated Chemical Vapor Deposition (iCVD) is a unique technique for producing polymeric surface coatings on micro structured surfaces while retaining the chemical functions of polymers. The aim of this thesis is to study the feasibility of iCVD deposition of bioinspired polymers with a double switchable function antimicrobial and antibiofouling on nanostructures. The candidate will have a profile of material chemist or polymer chemist with a strong affinity for microbiology and health applications with a MSc in material chemistry or polymer chemistry.

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Optimization of a liquid hydrocarbon synthesis reactor from a biobased syngaz and a renewable hydrogen production

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire Echangeurs et Réacteurs

01-10-2020

SL-DRT-20-0815

genevieve.geffraye@cea.fr

(.pdf)

During the past 20 years, « Biomass-to-liquid » processes have considerably grown. They aim at producing a large range of fuels (gasoline, kerozene, diesel, marine diesel oil) by coupling a biomass gazéificationgasification into syngaz syngas unit (CO+CO2+H2 mixture) and a Fischer-Tropsch (FT) synthesis unit. Many demonstration pilots have been operated within Europe. Nevertheless, the low H/C ratio of bio-based syngazsyngas from gasification requires the recycling or even a discharge of a huge quantity of CO2 at the inlet of gaseificationgasification process, which implies complex separation and has a negative impact on the overall valorization of bio-based carbon. Moreover, the possibility to realiserealize, in the same reactor, the Reverse Water Gas Shift (RWGS) and Fischer-Tropsch (FT) reaction in the same reactor with potassium promoted iron supported catalysts has been proved (Riedel et al. 1999) and validated in the frame of a CEA project PhD thesis (Panzone, 2019). Therefore, this concept coupled with the production of hydrogen from renewable electricity opens new opportunities to better valorize the carbonaceous content of biomass. The focus of the PhD is based on the FT synthesis under dynamic regime. On the one hand, the catalytic synthesis will be realized performed with dynamic variations of inlet gases composition (various ratios of CO2, CO, H2, CH4 ?) and total syngas flow in a fixed bed reactor. On the other hand, a reactor model will be built (coupling kinetic, thermodynamic, heat and mass transfer ? with COMSOL software) in order to understand and define and understand physico-chemical effect of such dynamic variations.

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Dopant activation in SiGe thin films: process optimization, characterization and numerical simulation

Département des Plateformes Technologiques (LETI)

Laboratoire

01-04-2020

SL-DRT-20-0817

sebastien.kerdiles@cea.fr

(.pdf)

CEA-LETI has recently installed in its state-of-the-art cleanrooms a new annealing equipment based on a nanosecond pulsed ultraviolet laser. This innovative thermal treatment enables processes at very high temperatures with extremely short durations, leading to heat confinement within a few hundred nanometers below the surface. Thanks to these unprecedented features, such nanosecond laser process is forseen as the next annealing technology generation with huge expectations especially for electronic devices such as advanced CMOS, memories and microsystems (MEMS). In the framework of a european research project (MUNDFAB, with partners laboratories from Germany, Austria, Italy and Poland), CEA-LETI and CNRS-LAAS jointly propose a doctoral research work targeting the development, the optimization and the simulation of dopant activation processes in SiGe thin films by nanosecond laser annealing. To reach this goal, the PhD student will combine experimental work in cleanrooms, electrical and physical characterization and multi-physics numerical simulations. Nanosecond laser annealing will be investigated in ultra-thin semiconducting films containing high concentrations of dopants, introduced directly during the epitaxial film growth or by a subsequent ion implantation. The PhD student will explore the limits of this disruptive annealing technique. Various technological approaches will be explored to tentatively control the crystalline quality of the laser annealed films, the germanium and dopant segregation and the surface roughness. The candidate should have strong knowledge in physics of semiconductors, materials science and microelectronics. He/she should appreciate team work and be rigorous, creative and endowed with good summarizing skills.

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Study of Lithium-plating phenomenon: Characterization and phenomenon simulation

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Analyse électrochimique et Post mortem

01-09-2020

SL-DRT-20-0818

sylvie.genies@cea.fr

(.pdf)

This thesis will be made in the framework of the PHOCUS program "Multi-scale simulation of batteries applied to electrode materials" In electric vehicles battery pack, Lithium-ion batteries must be able to accept fast charges, even at low temperatures. However, during charge process, formation of metallic lithium on the surface of the carbon-based, negative electrode or made of graphite and silicon mixture, can occur and accelerate the capacity loss of the battery and thus the autonomy of the vehicle. The study of this phenomenon known as Lithium-plating is therefore a key axis that would allow extending the life of batteries. Being a phenomenon appearing under current, it is necessary to use operando experimental methods in order to be able to characterize it in real time and to study its kinetics in function of the local conditions within the negative electrode. The thesis objective is to study this lithium-plating phenomenon by coupling electrochemical tests and lithium NMR technique. Indeed, this technique allows to identify the electronic environment of lithium, either metallic, in the oxidized state or intercalated within the carbon matrix and to give a quantification. These operando data will be used to feed and validate a multi-physics model at the electrode scale, developed in the framework of a previous thesis. Once validated, the simulation tool will be used to vary all main parameters to optimize the design of the electrodes and thus provide gain in battery life.

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biophysical analysis of exosomes for diagnosis, and precision medicine

Département Microtechnologies pour la Biologie et la Santé (LETI)

Laboratoire Chimie, Capteurs et Biomatériaux

01-10-2020

SL-DRT-20-0819

vincent.agache@cea.fr

(.pdf)

Cancer is the second leading cause of mortality in Europe, accounting for ~1.3M deaths in 2015. In this thesis we propose a new scenario for cancer liquid biopsy, based on the biophysical fingerprints of exosomes. Recent studies have shown exosomes to mediate signals for hypoxia driven epithelial-mesenchymal transition and metastasis, suggesting they could be powerful cancer biomarkers directly accessible in bodily fluids. There is increasing evidence of the specific biophysical link between exosomes and the parent cell. This thesis aims at developing and implementing new nanomechanical and microfluidics methods to investigate the biophysical signatures of exosomes from different cell lines, including healthy controls and cancer cells, in a perspective of early-cancer diagnosis, and precision medicine.

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New operating strategies and PEMFC system architectures for the optimization of performances

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Système Pemfc

01-10-2020

SL-DRT-20-0820

fabrice.micoud@cea.fr

(.pdf)

Increasing both the electrochemical performances and the lifespan of Proton Exchange Membrane Fuel Cell (PEMFC) is considered as a major challenge to deploy widely this technology . This PhD proposal aims at developing, realizing and studying in details the possibilities and the improvements by the use of new operating strategies and innovative PEMFC system architectures. The gains in terms of system management, electrical power/efficiency and durability will be investigated on laboratory test Bench (controlled and ideal operation for stacks) and on real system. This PhD work shall permit : i) to deepen our understanding of degradation mechanisms and kinetics within PEMFC stack; to validate experimentally our recent innovations for hardware architecture coupled with efficient and reliable monitoring system and iii) to increase the electrochemical performance and reach the best overall efficiency.

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Doping and confinement impacts on TiSi2 formation assisted by nanosecond laser annealing. Application to contacts for advanced imaging technologies

Département des Plateformes Technologiques (LETI)

Laboratoire

01-09-2020

SL-DRT-20-0821

sebastien.kerdiles@cea.fr

(.pdf)

Imaging technologies based on silicon devices are today widely spread in mobile phones, sensing and automotive applications. Many technical optimizations have enabled their increasing market penetration. Currently, in the optical sensor region, namely the pixels, electrical contacts are based on a silicide last integration, in which titanium silicide is formed after contact via etching. The electrical resistance of these ?TiSi' contacts is still too high and exhibits a strong lot-to-lot and within wafer dispersion. The current process will then not be a realistic option for mass production in the coming years. Recent improvements have been demonstrated by combining optimized Ti/TiN deposition with a disruptive thermal treatment available at CEA-LETI, namely the nanosecond laser annealing. The thesis work proposed targets to further develop these processes and understand the corresponding mechanisms and good results. This doctoral research is a collaboration between IM2NP (Institut Matériaux Microélectronique Nanosciences de Provence) in Marseille, CEA-LETI in Grenoble and STMicroelectronics R&D center in Crolles. The main goal of this thesis is to integrate and optimize innovative processes enabling good electrical contacts for advanced imaging technologies being developed in Crolles fab. First, the study will focus on the effects of doping and substrate nature on the titanium silicide formation. P+ and polycrystalline silicon active regions will be explored through sheet resistance measurements, X-ray diffraction and atom probe tomography. A set of optimal conditions will be determined. Then, the impact of the confinement on the silicide contact formation will be investigated using patterned production wafers. Finally, an innovative integration scheme will be proposed and tested on production wafers combining optimal preparation and deposition conditions with nanosecond laser annealing. This new path will be evaluated in terms of yield through electrical and optical characterizations.

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Elaboration and characterization of silicon / perovskite tandem solar cells with PIN architecture

Département des Technologies Solaires (LITEN)

Laboratoire Modules Photovoltaïques Organiques

01-09-2020

SL-DRT-20-0823

muriel.matheron@cea.fr

(.pdf)

Silicon / perovskite solar cells have recently shown major breakthoughs with record efficiencies reaching 28% for 2 terminal tandems (in which both subcells are connected in series). According to literature, best efficiencies are obtained with PIN architecture, due to optimized light management : minimized parasitic absorption from P layer in top cell, possibility to use transparent microcrystalline silicon as tunnel junction, or nanocrystalline silicon oxide with a better index matching property, leading to less parasitic reflection. Such materials (microcrystalline silicon and nanocrystalline silicon oxide) are developed within the frame of a PhD thesis at CEA-Liten, along with optimization of the perovskite single junction PIN architecture performed at CEA-Liten. The aim of the proposed PhD is to combine such developments into PIN tandems. Efforts will be devoted to in-depth characterization of the tunnel / recombination junctions and of the whole device. The goal is to identify charge transport mechanisms occurring at the interconnection layer between both subcells and to detect device limitations. To do so, electrical characterization of tests structures will be conducted, along with variable illumination measurements and photo/electroluminescence imaging of tandems. After a first analysis of PIN structures, new interconnection systems (obtained by chemical modification of interconnection materials) could be proposed and analyzed the same way.

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Recycling of fluorinated polymers contained in new technologies for energy (NTE)

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des Eco-procédés et EnVironnement

01-10-2019

SL-DRT-20-0825

emmanuel.billy@cea.fr

(.pdf)

Fluoropolymers are today very widely used for their mechanical and chemical properties and their durability. Polymers are unavoidable in the field of NTEs such as proton exchange membrane fuel cells (Nafion membrane in PEMFCs), batteries (PVDF at electrodes), or photovoltaic panels (EVA at the glass cell interface). With the advent of carbon-free technologies, the issue of recycling has become central to bringing these technologies to market. Historically, recycling processes were designed for processing different technologies and large volumes. This has led to the establishment of pyrometallurgical processes (high temperature) that are robust, but destructive and non-selective. In a context constrained by strategic, legislative (recycling rate) and environmental issues, it is necessary to recycle "more" and "better". This thesis aims at finding new wet or dry ways for the treatment of fluorinated compounds. The use of ionic liquids for the solubilization of polymers will be a preferred route. Their intrinsic physicochemical properties (very low volatility and flammability) make them ideal candidates for overcoming safety and environmental issues. The thesis work will be divided into three parts. Firstly, a state of the art will be realized for the evaluation of conventional processes and media for the treatment of fluorinated compounds. The state of the art will be tightened on the fluorinated polymers used in the field of new technologies for energy (NTE). A second part will deal with the chemistry of polymers and solvents in which a polymer can be dissolved. A third part of a fundamental nature will aim at linking the macroscopic results to the structural evolutions of the polymers.

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Nonsmooth time-stepping methods for 3D frictional contacts with geometrically nonlinear kinematics

Département Intelligence Ambiante et Systèmes Interactifs (LIST)

Laboratoire de Simulation Interactive

01-09-2020

SL-DRT-20-0826

xavier.merlhiot@cea.fr

(.pdf)

The simulation of the dynamics of multi-body systems with intermittent contacts has several applications, ranging from the engineering of the design of industrial products (circuit breakers, clockwork mechanisms ...) to the development of real-time simulators of complex systems (teleoperated robots operating in a hostile environment, offshore lifts, prototyping of assembly processes in the manufacturing industry, etc.) through the study of granular media. Even if numerical methods provided by nonsmooth mechanics nowadays lead globally to robust and efficient simulations of such systems, a certain number of application cases reach the limits of the state-of-the-art schemes and associated solvers. In particular, it is often necessary to invoke models of dry friction in 3D contact models (e.g. the Signorini-Coulomb contact law), in the presence of nonlinear contact kinematics. Indeed, the nonlinearity of those kinematics can come not only from the curvature of the surfaces in contact, but also from the kinematics of relative motion of the solids, which are often intrinsically nonlinear due to the presence of large rotations. This thesis aims to overcome the current limitations of the numerical methods in this type of situation, by proposing new numerical schemes as well as solvers adapted to application constraints. In this sense, particular attention will be paid to the robustness of the proposed methods (energy behavior, solvability of the constructed algebraic systems, etc.) and to the overall efficiency of the methods (achievable performance levels, possibilities of parallelization, applicability to real-time simulation contexts).

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From Ink to decal, understanding and optimization of PEMFC active layer

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Composants Pemfc

01-10-2020

SL-DRT-20-0827

marie.heitzmann@cea.fr

(.pdf)

When implementing active layers (AL) for proton exchange membrane fuel cells (PEMFC), we are confronted with a major problem that is the control of triple-phase boundary in the AL. In an environmental and economic logic, this is all the more important with the catalysts currently being developed (platinum-free catalysts, ultra low loading catalysts) where the number of active sites is reduced and therefore require optimized microstructure of AL and its interfaces to access all active sites. This thesis aims to study the influence of the implementation parameters that control the homogeneity of the catalytic ink (formulation, dispersion, stability), to develop a method of manufacturing AME by ultrasonic spray controlling the morphology of AL (distribution of ionomer, catalyst, porosity); and finally to evaluate the associated catalytic performances and to determine the optimal 3D structure adapted to these new catalysts.

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Pre-sizing method for multi-source hybrid systems includin the energy management strategy

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Architecture Electrique et Hybridation

01-09-2020

SL-DRT-20-0828

mylene.delhommais@cea.fr

(.pdf)

Embedded hybrid energy source systems are popular for the energy transition but are also complex to size: there is a strong dependence between the design of energy sources (battery, fuel cell, wind turbine, internal combustion engine, etc.) and the choice and configuration of the control law in real time (hybridization rate, real time strategy). The larger the number of sources, the more "complex" the problem to be solved is: the number of decision variables and the couplings between them become too important for traditional optimization methods. Pre-sizing such systems requires a new method of optimization. According to the state of the art of research on the pre-sizing by optimization of hybrid systems including the control law, the method will probably have to be based on a hybridization of different optimization techniques (branch and bound, stochastic, multi-level, quadratic, etc.). The objective of this hybridization would be to correctly manage the interdependencies of the energy sources with the control law during the pre-sizing phase while guaranteeing an optimal system with a reasonable calculation cost. The method proposed in the thesis could be tested, analyzed and improved on different applications such as the Energy Observer.

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Vulnerability study of electronic system against electromagnetic perturbation

Département Systèmes (LETI)

Centre d'Evaluation de la Sécurité des Technologies de l'Information

01-09-2020

SL-DRT-20-0830

(.pdf)

In the field of electronic system evaluation, the Leti ITSEF evaluates the component resistance against perturbation attacks using classical methods (voltage/clock glitch, glitch, photoelectric perturbation). Usual methods allow the evaluator to inject faults on the target with a high level of precision but require a physical access to the product in order to be very close to the area of the perturbation, which is sometimes unrealistic. Indeed, state of the art equipment used by the leti ITSEF for electromagnetic perturbations usually require to put a wire loop at less than 1mm of the component. The Leti ITSEF wants to develop a novel distant perturbation method based on electromagnetic perturbation. On the other hand, the CEA-DAM of Gramat has a serious experience in electromagnetic susceptibility of electronic system against electromagnetic aggressions. They want to use their technology in order to evaluate the vulnerability of a communicating system against an electromagnetic aggression. Objectives The research will be based on previous studies performed by the CEA-DAM of Gramat on the vulnerability of electronic systems against electromagnetic radiations, which is very effective for permanent or temporarily denial of service. First, it will be necessary to make the link between the Gramat technology that is very effective in term of service denial and the Leti technology, which allows a more precise effect. Then, a laboratory demonstrator will be developed to perform perturbation attacks on a representative target. Execution of the Thesis The first part of the thesis will be dedicated to the bibliography review on the effects of electromagnetic perturbations on electronic systems and the study of different ways to produce such electromagnetic perturbations. In the second part, the technical choice from the previous part will be tested against different representative targets of IoT devices. It will be necessary to measure the perturbation impact on different targets and to compare the results regarding a theoretical model. The last part will be dedicated to the prototype development.

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Optomechanical Cristal coupled to a SAW for microwave to infrared transduction

Département Composants Silicium (LETI)

Laboratoire Composants Micro-Capteurs

01-10-2020

SL-DRT-20-0832

guillaume.jourdan@cea.fr

(.pdf)

The most promising quantum computing platforms today are operated at very low temperatures at microwave frequencies, while telecommunication networks capable of preserving information in unconventional states (superposition, entanglement) use infrared (IR) photons at room temperature. Current frequency conversion means offer poor conversion efficiencies (10-6), which make them unusable for processing quantum information. A very highly efficient optical microwave converter is an essential step in linking these two frequency domains and creating a genuine network of distributed quantum computers (quantum internet). The proposed thesis topic aims to develop such a converter by exploiting the multi-scale coupling properties of mechanical nanoresonators. The first technological bricks have recently been produced with coupled mechanical/IR or mechanical/microwave systems in quantum regime. The aim here is to design an optomechanical crystal coupled to an IR resonator. The optomechanical crystal operating at microwave frequencies (GHz) will be actuated with the help of a SAW (Acoustic Wave Surface) powered by a microwave wave. This type of system offers a very low rate of insertion of conventional noise into the conversion process. The AlN deposition will be carried out in Leti's clean room, and then the subsequent steps can be continued at the PTA (academic clean room) which offers more flexibility in terms of the manufacturing process. A collaboration is in place with the Néel Institute (CNRS) in Grenoble to characterize these ultra-low temperature (<100mK) devices. This will allow the devices to be tested and compared with the expected performance. It will then be necessary to review the modelling and design based on the measurements in order to ensure that all phenomena are understood.

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New High Efficiency DC / DC Converter Technology with Integrated Galvanic Isolation for Medium Voltage DC grids

Département des Technologies Solaires (LITEN)

Laboratoire Systèmes PV

01-06-2020

SL-DRT-20-0833

Stephane.CATELLANI@cea.fr

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The primary sources of electrical energy used in renewable energy systems are DC. We can indicate below, the main characteristics in tension of the sources in question: -Photovoltaic (1.5 kVDC) -Systems of energy storage (800 V-1.5 kVDC) -Stacks EHT (950 VDC) -Electric Vehicle Batteries (800 VDC) On the other hand, the new power transmission networks are in direct current: -HVDC: 100 kVDC to 1.6 MVDC Some rail power systems are also DC: -Rain: 1.5kVDC, 3kVDC, experimental network project SNCF 10kVDC Architectures with DC collector are planned in the following applications: -Distribution of energy in charging stations for electric vehicles -Nautical ship propulsion systems -Electrical conversion lines of railway traction units -Photovoltaic power generation Stationary storage of electrical energy The objective of this thesis work will be to obtain a modular DC / DC converter brick compatible with the voltage levels delivered by the ENR sources and allowing to inject on the DC medium voltage. Electrical isolation of primary sources will remain unchanged: therefore, to ensure the isolation of sources, very high efficiency transformer technologies (> 99.5%), integrated in the static conversion stages -Injection can be done on a DC 9kV network (experimental network SNCF) -The power electronics will be made with HT SiC semiconductors whose current performance is much higher than Si equivalents. The DTNM will bring its expertise on magnetic materials for the design of the integrated transformer in the conversion stages.

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Comparison of the safety of Li batteries with liquid electrolyte and solid state. Role of the different materials involved in the mechanisms of thermal runaway.

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Analyse électrochimique et Post mortem

01-09-2020

SL-DRT-20-0834

remi.vincent@cea.fr

(.pdf)

Currently, the technology of all solid state batteries is very popular because it represents one of the credible ways to reach the 400Wh/Kg. By improving safety, this technology allows the integration of lithium metal and the most energetic cathode materials. Nevertheless, all-solid technologies are not totally inert. Thus, it has been demonstrate that the thermal runaway energy is equal to the sum of the energies of the chemical and electrochemical reactions contained in the cell. Based on this methodology, the thesis will identify the security potential of new all solid state technologies. For this, characterizations such as DSC, TGAMS and calorimetry will be implemented to identify the reactivity of the materials of a cell as well as their interactions (e.g. presence or absence of SEI). Based on these analyzes and the models developed at CEA, the PHD will propose a change of scale to predict the reaction kinetics of a cell and thus predict the state of safety of the technology before the realization of a real cell. This will bring elements for the emergence of a new technology.

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Brillouin microspectroscopy for 3D cell microculture

Département Microtechnologies pour la Biologie et la Santé (LETI)

Laboratoire Systèmes d'Imagerie pour le Vivant

01-10-2019

SL-DRT-20-0835

jean-charles.baritaux@cea.fr

(.pdf)

3D cell cultures are in-vitro models that are increasingly used for fundamental research, as well as for novel clinical and therapeutic applications. There is evidence that the biomechanical properties of these cellular structures are intricately linked with physiological parameters such as viability, fonctionality and response to treatment for instance. Brillouin Light Scattering Microscopy (µBLS) is an emerging technique in bioimaging for measuring the viscoelastic properties at the micrometer scale. It relies on the analysis of the light inelastically scattered by the phonons propagating in the medium, in the Brillouin scattering process. The goal of this PhD thesis is to develop an innovative µBLS system for the monitoring of 3D microcultures, and go towards the proof of concept that the mechanical properties measured in BLS may be used to infer the physiological parameters of interest. The PhD student will work on a custom state of the art µBLS instrument built in the Laboratory for bioimaging systems (LSIV), at CEA Leti in Grenoble, France, and will experiment with several types of 3D cultures, to demonstrate the capabilities of this new approach. Candidates with a strong background in optics, biophysics, experimental physics, or electrical engineering, and who are keen of biomedical application of technology are encouraged to apply.

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Optimization of countermeasure insertion for the safety of Integrated Circuits.

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Calcul Embarqué

01-10-2019

SL-DRT-20-0836

lilia.zaourar@cea.fr

(.pdf)

Hardware Trojans (HTs) are malicious blocks inserted into Systems on Chip (SoC) by untrusted parties in the IC design/manufacturing flow. They have been identified as a realistic threat, among others to the car safety and military. HTs aim to change SoCs' behavior, ranging from denial of service, decreased reliability, to confidential information leakage. Such attacks lead to multi-billions dollars loss per year for the semiconductor industry. Countermeasures against HTs exist, divided into two categories: detection and prevention. Ten years of research have shown that detection is a very challenging task, knowing the stealthy nature of the threat and the multiple possible forms of HTs. Prevention consists in modifying the design flow to take into account security issues. Despite its potential cost, it represents a more effective way to overcome HT insertion. So-called Design-for-Hardware-Trust (DfHT) methods exist, with various goals and impacts on performance. The MOOSIC project proposes a framework dedicated to security that can be integrated into the conventional IC design flow. The goal is to take into account, as early in the design phase, both countermeasures against HTs and performance, to ensure that the SoC behavior is guaranteed despite untrusted IPs vendors or foundry. Towards this objective, the project envisions to establish and evaluate security properties and then integrate them during synthesis with multi-objective optimization techniques, which will be built on a mathematical modeling of the problem that takes into account both the performance and the HTs?effects. It is indeed necessary to find a good compromise between the level of security sought after and performance. The candidate will have to propose a complete mathematical model of the problem that supports all the constraints and objectives (security, area, frequency, consumption). He will then have to develop optimization algorithms to effectively solve the problem of insertion of countermeasures on conventional criteria (time, area, consumption). Finally, a validation of the methodology on simple first examples is envisaged as well as some test on industrial use cases improvement with some improvement if necessary. The thesis will take place at the CEA LIST LCE and will be led by the LIP6 / Sorbonne University in Paris.

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Waveguide adressing architecture for retinal projection display integration

Département d'Optronique (LETI)

Laboratoire Architecture Systèmes Photoniques

01-10-2020

SL-DRT-20-0837

christophe.martinez@cea.fr

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CEA Tech Leti is involved for several years in the development of an original concept of optical device for Augmented Reality applications. This retinal projection display concept is based on advanced technological process: SiN waveguide photonics and holographic printers. The PhD is dedicated to the first technology and concern the design of addressing waveguide architecture. It will be done in continuity of a former ending PhD on the design of dense waveguide networks in the visible range. This network, that has to interact with pixelated holograms, has to be addressed by an array of optical emitters. The PhD student will simulate and develop the waveguide multi-level architecture needed to link the emitters (LED, VCESL, laser array) to the waveguides network. He will also follow the technological steps in the clean room and bring the device characterization. The Phd will end by the conception and realization of a prototype demonstrating the interaction between an optical emitter array and a digital hologram through a waveguide network.

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Systematic construction and interpretation of electromagnetic leakages models for embedded processors

Département Systèmes (LETI)

Laboratoire Sécurité des Objets et des Systèmes Physiques

01-10-2020

SL-DRT-20-0838

maxime.lecomte@cea.fr

(.pdf)

Side-channel attacks consist in measuring the physical activity emitted by a circuit (processor, microcontroller or cryptographic accelerator) to extract secrets. The consumption of the circuit or the electromagnetic emanation are the most commonly exploited signals. Due to the development of the Internet of Things (IoT), more and more systems are exposed to these attacks. Unfortunately, integrating countermeasures (software or hardware) against such attacks is extremely expensive. Therefore, it is essential to have an accurate idea of side-channel leakages as early as possible in the design phases. On the one hand to target countermeasures on critical areas and on the other hand to have a realistic view of leakages in order to automate the application of countermeasures. The thesis topic is the exploration of electromagnetic leakage models and different ways of interpreting them. The general objective of this work is to model the leakages of a processor based on its state at different abstraction level: Register Transfer Level (RTL), micro-architecture or even instruction set simulator (ISS). The LSOSP laboratory of CEA-LETI where the thesis will take place has a strong experience on physical measurements and has already performed preliminary research on the subject. Therefore, the candidate will start from these results and will perform physical measurements and manipulate different logic models to create a precise leakage model of the targeted processor.

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Tunable SOI-CMOS/GaN HPA for 5G infrastructure

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Architectures Intégrées Radiofréquences

01-10-2020

SL-DRT-20-0839

ayssar.serhan@cea.fr

(.pdf)

RF GaN technology has emerged as a strong candidate for high power 5G PA (HPA). The high power density, low output capacitance, and high breakdown voltage of GaN transistors make them attractive for the 5G small-cell market that requires several watts of output power at high frequencies (up to 40GHz). In this Ph.D. work, the student will investigate the heterogeneous SOI-CMOS/GaN Integration of a mmWave high-efficiency HPA. The output stage of the HPA will use Doherty architecture in order to achieve high-efficiency in the back-off region. It will be implemented on GaN to achieve the required power levels. To avoid the performances degradation of the Doherty stage over frequency, the input phase and driver level of the main and auxiliary transistors of the Doherty PA need to be carefully controlled. The driver stage of the Doherty stage will be implemented on SOI technology in order to enable tunability of the drive signals (phase and amplitude) using reconfigurable passives on SOI. This digitally assisted HPA will allow the optimization of both linearity and efficiency over wide frequency range of operation in a compact solution. This PhD thésis is proposed as an international PhD, diploma from University of Grneoble Alps, in collaboration with a European Partner. This PhD maybe a strong opportunity for the student for mutual collaboration, and a stay abroad.

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Improvement of Diffusion Welding assembly process for large exchangers manufacturing : identification of critical welding defects and modeling of their closure kinetics

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire Conception et Assemblages

01-09-2020

SL-DRT-20-0841

isabelle.moro@cea.fr

(.pdf)

The diffusion bonding method has been used for many years in order to manufacture heat exchangers. Concretely, these exchangers consist of machined plates, stacked, then put under vacuum in a container and then introduced into a Hot Isostatic Compression (CIC) furnace which, by the simultaneous application of a high pressure and a high temperature, allows the plates to be assembled together by atomic diffusion. The main objectives of the thesis are on the one hand the improvement of the model allowing to describe the kinetics for closing the pores at the interfaces of welding, using both experimental and numerical approaches, and on the other hand the quantification of the influence of different geometries and residual pore levels on the mechanical strength of these interfaces. This will ultimately allow "degraded" CIC cycles to be defined so that they allow a minimum of macroscopic deformation of the exchanger during its assembly by CIC, even if it means accepting defects. However, it should be possible to distinguish allowable defects from those that are not, and via modeling to predict their frequency, their exact geometries and their preferential locations. This thesis presents both experimental and numerical aspects in a context of a strong technological challenge. As a first step, the study will focus on a reference material of type 316L that has already been the subject of numerous preliminary studies. Its behavior has already been studied in a temperature range from ambient to more than 1000 ° C, and a suitable constitutive law and associated parameters have been determined and validated. Numerous structures of 316L type material have already been assembled by CIC, and important feedback already exists within the laboratory concerning the assembly of this type of material. The work to be done during the thesis will consist in the realization of assemblies by CIC on sheets having different types of defects and varied geometries, these defects having been carefully characterized. A follow-up of the progressive elimination of these defects during the welding diffusion and the modeling of this process via the model of Hill and Wallach will make it possible to highlight shortcomings or inadequacies of the different mechanisms constitutive of this same model, which did not never been realized until then. This work will lead to an improvement of the Hill and Wallach model currently used. In a second step, we will seek to identify the harmfulness of different defects according to their geometry, their frequency and their location. To do this, typical assemblies will be manufactured and tested. It will also be necessary to identify the most relevant mechanical test (s), which may also be a function of the location of the defect in the assembly. Thus, a fault located in a side bank of a heat exchanger does not see during the operation of the exchanger the same thermo-mechanical loading as a fault located in an isthmus. This work will eventually make it possible to differentiate in an assembly the welding defects with prohibitive interfaces, from those acceptable. In the end, these two lines of research will allow, on the one hand, via modeling to predict the geometry of the residual pores at the interfaces after assembly by CIC, and on the other hand to be able to predict if these defects after diffusion welding are critical for the structure or not. It will thus be possible to define, in terms of pressure and temperature evolution during assembly by CIC, an optimized cycle which will allow both the minimization of the macroscopic deformations of the structure, and the obtaining of a welding sufficient to ensure the operation of the exchanger.

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Study and Improvement of the formation step of next generation Li-Ion batteries

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Prototypage et Procédés Composants

01-10-2020

SL-DRT-20-0843

yvan.reynier@cea.fr

(.pdf)

Electrical formation of Li-ion batteries is a little studied subject in academic circles, while it represents 30% of the cost of production of the cell and conditions its performance (life, resistance ...). Most studies remain empirical [1-5] or protected by industrial secrecy. The aim of the thesis is to establish a direct link between the parameters of the formation step and the resulting electrochemical performance, using a protocol coupling electrochemical measurements and physicochemical characterization. During his training, the student will develop the monitoring methodology and then determine the most influential parameters. Subsequently, he will apply these results to representative accumulators using design of experiment methodology to optimize the formation step.

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High-performance TeraHertz detectors for passive imaging

Département d'Optronique (LETI)

Laboratoire d'Imagerie thermique et THz

01-10-2020

SL-DRT-20-0845

abdelkader.aliane@cea.fr

(.pdf)

The Terahertz (THz, 300 GHz-3 THz) frequency band triggers a high interest in numerous application domains (imaging, spectrometry, industrial inspection and test, surveillance, instrumentation) thanks to the good propagation properties through non-conductive materials, the presence of resonance frequencies typical of numerous molecules, the potential for high spatial resolution, and their non-ionizing properties. CEA-LETI is a world-leading research laboratory in THz technologies and developed several THz detectors and imaging circuits, both cooled and uncooled, for imaging applications. Since 2018, a THz imager developed and manufactured at CEA-LETI is available commercially in the THz camera from i2S (www.i2s.fr/en). The objective of this PhD thesis is to investigate and develop a new THz detector technology with a significant breakthrough in terms of sensitivity enabling passive imaging applications. The PhD student will work in a team gathering all the expertise, instrumentation and facilities required in this project. He/she will take part in all the activities involved in the development of these new detectors, in particular system studies, design and simulation (thermal, mechanical, electromechanical), fabrication, and characterization.

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Consideration of the risk of propagation of thermal runaway in the development of battery modules. Experimental approach and modeling tool taking into account gas generation.

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Analyse électrochimique et Post mortem

01-09-2020

SL-DRT-20-0846

remi.vincent@cea.fr

(.pdf)

The PHD proposes to study the propagation of thermal runaway in a battery module. The different modes of heat transfer (radiation, conduction and convection) will be quantified and their impacts for the module design will be evaluated. For example, the energy shares released in the gases or the cell will be determined, as well as the probabilities of tearing the bucket and the impact of the thermal conductivity of the foils and welds. This study will deal with the realization of abusive tests on mini-module as well as with a modelization of CFD type (Start CCM + software). Both approaches will feed each other to obtain a predictive model of runaway. The first step will consist in validating that the simulation reproduces well the predominant phenomena to, in a second time, propose optimizations which will be validated in their turn by the experiment. Finally, the thesis will propose in addition to a fine evaluation of the main parameters in the propagation of the thermal runaway, innovative module designs with mitigation solutions specially adapted according to the cells and the targeted application.

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Understanding PEMFC small channels flooding phenomena

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Système Pemfc

01-10-2020

SL-DRT-20-0847

jean-philippe.poirot@cea.fr

(.pdf)

Proton exchange membrane fuel cells (PEMFC) are now considered as a relevant solution for the production of decarbonated electric energy, both for transport and stationary applications. Fluid management within these cells has a significant impact on their performance and durability. The flooding phenomena due to the accumulation of liquid water are detrimental to the operation of the cells, causing performance losses and long term degradation that may be irreversible. With the use of increasingly thin channels in ever more compact fuel cell stacks, these phenomena are becoming more and more frequent. The goal of this thesis is to progress in the understanding of flooding in PEMFCs. The work will consist in analyzing the link between the operating conditions, the design of the channels and the materials used in the cell. On the one hand, they will rely on many experimental results, some of which include neutron images, and secondly on multi-physics models at different scales. This will allow to couple a local approach, at the scale of a fraction of the length of a channel, and a global approach at the scale of the complete cell.

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Development and characterization of a new process for interconnection of high-performance electronic components by sintering nanoparticles

Département Composants Silicium (LETI)

Laboratoire Packaging et 3D

01-10-2019

SL-DRT-20-0848

jcsouriau@cea.fr

(.pdf)

Electronic components are becoming more and more efficient. Packaging must then adapt so as not to be the limiting factor. All current studies aim to improve the performance of the modules while taking into account the environmental context, which aims to limit the use of substances harmful to man and the environment. Sintering, particularly silver sintering, stands out today for the integration of semiconductor chips on substrates. It has excellent thermal and electrical performances (silver is the best conductor among all metals), and is perfectly stable in temperature (the sintering process is carried out below 300°C, but then supports temperatures of more than 900°C). In addition, the sintered joint is free of harmful substances, since it contains only silver. Today, power electronics is the main application that drives developments of sintering interconnection, with a use for electric or hybrid vehicles, for aeronautics, etc. LED also turn to sintering (especially automotive lighting). The miniaturization of microsystems raises new challenges, such as the development of assembly processes adapted to sintering. The aim of the thesis will be to develop a sintering process for a direct contact semiconductor chip (Flip-Chip) on a substrate with pads whose diameter is less than 300µm. The process will be tested and characterized on a test vehicle designed as part of this study.

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Abatement of gaseous inorganic pollutant release in biomass and waste gasification

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire de Conversion de ressources Carbonées par voie Sèche

01-10-2020

SL-DRT-20-0850

sylvie.valin@cea.fr

(.pdf)

The objective of the thesis is to characterize the release of gaseous inorganic pollutants (H2S, COS, HCl, NaCl, KCl in particular) in biomass and waste gasification, and to propose and test in-situ methods to limit this release. These methods, based on chemical interactions between inorganic elements, will mainly consist in the use of additives or in implementation of resource blends. Gasification allows producing a synthesis gas which can be used in cogeneration (heat and electricity) or for the synthesis of liquid or gaseous fuel. However, inorganic volatile pollutants must be removed before the final application, because of environmental emission standards, as well as because of their corrosive nature (HCl, KCl, NaCl), or of their poisoning influence on catalysts used for synthesis (H2S). The proposed approach will consist in, firstly, performing thermodynamic simulations so as to understand the behavior of inorganic elements in gasification, and to define and interpret the experiments to be performed in the laboratory. Analytical experiments will be performed at laboratory and pilot scale, and will be associated with gas analyses and characterization of the residual ash (SEM, XRD). The obtained results will be used to better control the inorganic pollutant concentrations in synthesis gas as a function of the variability of the carbonaceous resources, and to precise the cleaning process before the final application.

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Modeling phase transitions in LIB active materials

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Modélisation multi-échelle et suivi Performance

01-09-2020

SL-DRT-20-0851

marion.chandesris@cea.fr

(.pdf)

For Generation 3 lithium-ion batteries (LIB), the materials have reached a fair maturity level and current challenges focus on optimization of these technologies under various and most of the case antagonist constraints. Modeling and simulation numerical tools allow to tackle these optimization questions but suffer from a low knowledge of active materials physical and electrochemical properties. The aim of this thesis is to investigate the link between the crystallographic structures of LIB active materials and their thermodynamic properties at and out of equilibrium. In particular, this thesis work aims at modeling and simulating phase transitions occurring during lithium insertion in lamellar active materials (graphite at the negative and alloy of transition metal oxide at the positive) to understand (i) staging phenomena, which corresponds to periodic ordering of lithium and (ii) shift in the planes of the host materials. Progress in our understanding of these two phenomena and their coupling should bring a better comprehension of the main physical properties of a large majority of lamellar active materials.

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Task oriented gripper design methodology for robotic manipulation ? application to pluridigital grippers with flexible joints

Département Intelligence Ambiante et Systèmes Interactifs (LIST)

Laboratoire d'Architecture des Systèmes Robotiques

01-09-2020

SL-DRT-20-0852

florian.gosselin@cea.fr

(.pdf)

Robots are increasingly visible in our environment, with applications in e.g. fruits and vegetables picking, food packaging and human-robot interactions. All these applications require an efficient solution for grasping and manipulating many different objects. Several approaches have been proposed so far to solve this issue, ranging from double jaw pliers which are very efficient for the grasping of specific tools but cannot deal with other objects nor manipulate them finely, to pluridigital grippers which offer a higher grasping stability and can be reconfigured to grasp various objects. The latter's mechanical complexity and control difficulty however still limit their use in practice to grasping tasks and slow their spread in industry and service robotics. This thesis aims to solve these limitations by combining innovative technological solutions based on the latest advances in flexible structures and 3D printing, distributed sensors and actuators, with task oriented mechanisms synthesis methods, to develop a task oriented design methodology for versatile grasping and dexterous manipulation mechanisms. This methodology will be used for the design and control of novel grippers making use of innovative and adaptive structures that conform automatically to the objects' geometry and can generate sufficiently large in-hand movements. These developments will be validated experimentally on one or several demonstrators.

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Design of a 3D stacked smart imager dedicated to neural network processing

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Adéquation Algorithmes Architecture

01-10-2020

SL-DRT-20-0855

stephane.chevobbe@cea.fr

(.pdf)

The 3D stacked silicon technologies allow the fabrication of new kinds of smart vision sensors by vertically coupling image sensor and specific processors or memories inside the same chip. Some research teams develop 3D stacked vision chip either to increase the quality of the sensor or to embed high powerful processors inside the chip closely coupled to the imager, as we did by developing the RETINE chip. Deep neural networks are widely used in many application domains including computer vision. A lot of research consists in increasing the power efficiency and decreasing the power consumption of embedded systems dedicated to neural networks execution. In this PhD thesis we propose to evaluate the opportunities offered by 3D stacked silicon technologies to question and envision new kind of digital 3D stacked vision chip embedding neural network hardware. In this PhD thesis we wish to study the contribution of 3D integration technologies in an intelligent imager integrating neural network processing functions. We will focus this study mainly on deep neural networks, however other types of neural networks can be evaluated. The architectural contribution expected from this thesis is the study and design of an efficient and low-power computing architecture that meets the high constraints imposed by deep neural networks, namely the need for very regular high-performance computing and the very high need for memory

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Suspended vertical diodes for LWIR detection

Département d'Optronique (LETI)

Laboratoire d'Imagerie thermique et THz

01-09-2020

SL-DRT-20-0856

patrick.leduc@cea.fr

(.pdf)

Uncooled thermal detectors absorb the infrared flux for wavelengths from 7µm to 14µm. This corresponds to an atmospheric transmission window and to the maximum emission of a blackbody at 300K, which enables the detection of temperature variations of less than 100mK. The operating principle of microbolometers is based on the temperature measurement of a suspended membrane absorbing the infrared flux. The thermal transducer is the sensitive element of the microbolomètre, which determines its signal-to-noise ratio and therefore the performance of the bolometric pixel. In recent years, the miniaturization of microbolometer technologies has led to pixel size reduction down to 12 µm and has been accompanied by a reduction of manufacturing costs. However the current technology reaches its limits in a way that it becomes extremely difficult to pursue the pixel size reduction. The thesis topic is the study of a breakthrough technology for microbolometers. Unlike conventional detectors, which use thermistor for the thermal transduction, the proposed research topic will examine an original technology based on vertical diodes. The subject will focus on characterizing and modeling the performance of such a device.

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Development of superconducting single photon detectors and receiver circuits for quantum communications

Département d'Optronique (LETI)

Laboratoire d'Intégration Photonique sur Silicium

01-10-2020

SL-DRT-20-0859

segolene.olivier@cea.fr

(.pdf)

Quantum information processing turns out to be a major challenge for our society with the development of quantum computers, able to solve complex problems much more rapidly than a classical computer, and of quantum communications providing absolute security for information transfer. The development of integrated technologies is essential for the future large-scale deployment of compact and low-cost quantum information systems. CEA-Leti has been developing for several years a silicon photonics platform, providing integrated components and circuits for various applications such as telecom/datacom, lidars and more recently quantum communications. The objective of this PhD is in a first step to design, fabricate in the Leti clean room and characterize a new generation of advanced superconducting quantum detectors on Silicon able to detect single photons with above 90% efficiency. In a second step, these detectors will be integrated into secure quantum communication circuits. This PhD will benefit from collaborations with academic laboratories in France and in Europe.

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Reversible hydrogen storage material based on amine metal borohydrides: Synthesis and Regneration of spent fuel for a circular economy

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des Eco-procédés et EnVironnement

01-09-2020

SL-DRT-20-0860

philippe.capron@cea.fr

(.pdf)

Hydrogen is considered as the energy carrier of tomorrow. However, in addition to the fact that the production and distribution chain is not yet operational, there are real scientific, technological and economic barriers to its storage for mobile or stationary applications. Although there are currently storage solutions in compressed or chemisorbed form in metal hydrides, the performance and associated costs of these solutions only partially fulfil the specifications of the various applications. Ammoniates of metal borohydrides have shown great promise as a higher capacity next generation chemical hydrogen storage medium. CEA/LITEN has developed several M-B-N-H systems that deliver more than 10 wt% practical hydrogen capacity below 250°C. Our novel and scalable synthesis approach for these materials allowed in-depth understanding of dehydrogenation process. The remaining challenge is the development of chemical rehydrogenation routes for the spent fuel (partially hydrogenated boron nitride) with high yield. Based on our preliminary investigation, the proposed thesis project will focus on the microwave-assisted digestion of boron nitride with anhydrous hydrochloric acid followed by hydrodechlorination process enabled via a catalyst-solvent mixture. Obtained diborane and ammonia products can become the synthesis precursors enabling the full recyclability. On the other hand, the development and optimization of these rehydrogenation processes will require chemical and structural analysis in order to understand and improve the role of hydrogenation catalyst-solvent mixture. In this context, in-operando experiments using large instruments will be conducted in collaboration with INAC.

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Few-shot Learning and Domain Adaptation for Information Extraction

Département Intelligence Ambiante et Systèmes Interactifs (LIST)

Laboratoire Analyse Sémantique Textes et Images

01-10-2020

SL-DRT-20-0862

romaric.besancon@cea.fr

(.pdf)

Automated Information Extraction from texts is necessary for all applications that require the processing of large amounts of textual data, but the development of such systems, adapted to a specific domain, is still very costly because it requires to specify very precisely the information to extract or to produce lots of annotated data in order to train machine learning models. The goal of this thesis is to work on new ways to reduce the cost of domain adapation for information extraction systems. The proposed approach is based on two axes: (1) the development of a generic information extraction model, based on a model of semantic frames representing general events that can be made more generic by the use of word embeddings, such as BERT or ELMO and (2) the study of methods to automatically adapt this generic model to a new domain, exploiting only few annotated examples: this adaptation will rely on approaches such as distant supervision, active learning or transfer learning.

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Optimization of the recycling of cathode materials for lithium-ion batteries by hydrometallurgical processes: study of the reactivity of transition metal oxides with ionic liquids.

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Nanocaractérisation et Nanosécurité

01-09-2020

SL-DRT-20-0863

anass.benayad@cea.fr

(.pdf)

The fast demand for electrical vehicle as well as the need to increase our capacity to store intermittent energy sources induce a strong demand for Li-ion batteries. Production is not only costly in terms of energy but also regarding pollution, which means that they must be recycled. Indeed, separately, the components can have a second life in new batteries. Thus reducing the dependency on the battery material considered critical and strategic by the European Union. Their treatment is imperative for the massive development of electric vehicles in France and Europe. The end of life of Li-ion batteries is a major industrial issue throughout the recycling chain. Recycling batteries, which are complex in composition (polymer, metals or plastics), is a technological and environmental challenge. Hydrometallurgical processes offer better prospects for reducing energy costs for the treatment of this type of waste and meeting the global demand for high-purity precursors for the synthesis of new electrode materials. However, many technological building blocks of recycling processes must be developed to meet the economic and environmental challenges of battery recycling. The use of ionic liquids, presents an alternative for their use in various process bricks to reduce the risks associated with conventional solvents. Due to their low saturation vapor pressure, they are non-flammable and non-volatile, reducing the risks associated with conventional media (aqueous and organic). However, the reactivity of the materials making up Li-ion batteries (cathode materials based on transition metal oxides, spectators, collectors, etc.) with ionic liquids is not well studied. The purpose of this thesis is to study the reactivity of anode and cathode materials based on transition oxide metals with respect to solvents based on ionic liquids by coupling physico-chemical and electrochemical characterization in post-mortem mode and operando. This coupling will provide solutions for the extraction of transition metals to reintegrate them into new applications for energy storage. The candidate must hold a master's degree in research (M2) or an engineering degree in materials science, physics or equivalent. A background in electrochemistry will be suitable He or she must be motivated to work in a multidisciplinary team. The candidate will be welcomed in the laboratories of the L2N and L2EV of the DTNM to carry out his internship work.

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Selection and optimisation of silicon anodes for all solid state batteries

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Matériaux

01-01-2020

SL-DRT-20-0864

cedric.haon@cea.fr

The success of energy transition will depend strongly on mobility. Electric vehicles will reduce CO2 emissions but the deployment of e-cars is linked to improvements of actual Li-ion batteries in term of energy density, cycle life and safety. In general, conventional Li-ion batteries (LIB) contain a cathode (lithiated Ni-Mn-Co oxide), anode (graphite), liquid electrolyte (carbonate based solvents containing lithium salt) and separator (to avoid short-circuit and allow the shuttling of Li+ ions). LIBs raise safety issues due to their volatile and flammable electrolytes. In addition, low specific capacity of graphite (372 mAh g-1) also hampers the wider acceptance of current LIB, as in electric vehicles. In terms of safety, SSBs are an efficient and viable alternate to conventional LIBs as they do not contain any flammable organic electrolyte. Beside, SSE often show a wide electrochemical potential window, an advantage to increase the energy density of the battery. Many SSBs have been demonstrated using metallic lithium (Li) as anode for simplicity, but Li proved instable against nearly all developed solid-state electrolyte (SSE) and to form dendrites, and is difficult to plate in very thin films. As these detrimental issues are specific to Li metal, a replacement with alloy-based anodes sounds appropriate in developing SSBs. For example, silicon (Si) based anodes are handled in air and high temperature tolerant. Largely Earth abundant, Si can deliver a very high theoretical capacity of 3579 mAh.g-1 or 8303 mAh.cm-3 at an operating voltage of 0.4 V vs Li+/Li. However, the mechanical integrity of the electrodes in SSBs might get severely affected by the large volume changes (>300%) of Si during cycling, resulting in the formation of cracks, pulverization and delamination, which is a critical point. Thus, establishing and maintaining a good contact between electrode and electrolyte throughout cycling is the prerequisite for high energy density SSBs with Si anode. Research and development (R&D) of Si-based SSBs has focus on thin film form of Si as it is expected to address the mechanical issue and charge transfer resistance at interfaces. However, thin film anodes deliver a very low areal capacity (0.3 mAh.cm-2) compared to those of commercial anodes of LIBs (2-5 mAh.cm-2) due to the poor loading of active material. The proposed work deals with the research of silicon materials ? solid electrolytes couples and understanding of chemical and mechanical stability at the interfaces. Silicon materials will be tuned to change particle size and morphology and surface chemistry. Several types of silicon materials will be studied based on our know-how. One or several solid electrolytes will be selected at the beginning of the Ph.D. Understanding of reactivity and fracture mechanisms at the interfaces will be based on in-situ electrochemical characterizations and post-mortem analyses.

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Advanced network management for controlling the real-time redeployment of a mobile network infrastructure under traffic performance constraints

Département Intelligence Ambiante et Systèmes Interactifs (LIST)

Laboratoire Systèmes Communiquants

01-09-2020

SL-DRT-20-0865

Michael.Boc@cea.fr

(.pdf)

The digitization of industries introduces the need for providing high-speed wireless connectivity on industrial sites, which is extremely difficult due to the constraints imposed by these environments. To address them, this PhD thesis will investigate opportunities to increase real-time reconfiguration capabilities of the wireless infrastructure by means of an SDN-oriented management of the network. This network management will control the mobility of the infrastructure equipment as an additional degree of freedom in order to improve the performance of the data flows. This capability should provide two key benefits: 1) not having to rely on a lengthy and costly planning phase for network deployment, and 2) being able to implement new and more sophisticated network reconfiguration strategies to increase its overall performance level at any time. The mobility of the infrastructure could be provided by mobile robots that can be controlled through an SDN protocol and carrying some of the network equipment. In the case of a nuclear dismantling operation, for example, we could consider the wireless communication infrastructure as being composed of a fleet of mobile robots (terrestrial or aerial) whose mobility is managed by a network management system (SDN) in charge of ensuring the proper performance of the connectivity for dismantling robots remotely operated. The objective of the proposed thesis work is to define an advanced and centralized network management system for the control of the real-time redeployment of a mobile network infrastructure under performance constraints of data flows. This system should be able to 1) identify when a topological change becomes relevant considering the types of data flow performance problems and the limitations of existing network optimization solutions, 2) to define and pilot the redeployment of the network infrastructure in order to improve the performance of these data flows.

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Modeling of biomass torrefaction at pilot scale with data measured at small scale

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire de Conversion de ressources Carbonées par voie Sèche

01-10-2020

SL-DRT-20-0866

Muriel.Marchand@cea.fr

(.pdf)

Torrefaction is a thermal pretreatment applied to biomass, carried out under neutral atmosphere for several tens of minutes, at temperatures between 200 and 300°C. Once treated, the solid exhibits properties closer to those of coal (fossil), making it suitable to the same industrial facilities as this latter. Namely, torrefaction enhances the carbon content in the solid, thus increasing the interest of its thermochemical conversion to contribute to the closure of the carbon cycle. The biomass platform of CEA Grenoble has been equipped with a pilot-scale torrefaction oven (capacity: 150kg/h of wood). The results obtained in this pilot oven are always out of sync with the torrefaction data measured in the laboratory. Therefore, the validity of the change of scale for this process is questionable. The aim of this thesis is to improve the extrapolation at pilot scale of data measured with small analytical equipment. Three successive phd prepared in the laboratory, have led to a model representing the different chemical transformations of biomass during torrefaction. This model will be used in the proposed phd. This work will require to perform a lot of experimental investigations, in the laboratory (small scale) as well as to participate to torrefaction campaigns with the pilot.

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Study of heterogeneous damage in Li-ion batteries related to cell design and development of associate ageing model at cell level

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Analyse électrochimique et Post mortem

01-10-2020

SL-DRT-20-0867

olivier.raccurt@cea.fr

(.pdf)

This thesis topic focuses on the study of Li-ion cell ageing and in particular on the impact of the internal architecture of the cell on the generation of localised degradation. Although Li-ion technology is undergoing strong development, cell formats are not standardized. A wide variety of designs are currently available on market (cylindrical, prismatic or laminate) with capacities ranging from a few Ah to several tens of Ah and a variety of assembly modes (winding, stacking). The architecture of the cells has an impact on degradation phenomena during operation, directly affecting the life and safety of the batteries. During ageing, heterogeneities at the electrode level have been observed but are still little studied. Moreover, current modelling at the cell scale considers the degradation to be homogeneous. The aim of this thesis will be first to identify the existing relationships between cell architectures and the generation of localized degradation on the internal components of the cell. This in order to integrate these inhomogeneities in the models developed by the CEA up to the cell scale. The work requested concerns both experimental studies and modelling. In order to carry out his thesis work, the candidate will be hosted at the Laboratory of Electrochemical and Postmortem Analysis of CEA LITEN where he will carry out electrochemical tests and post-mortem analyses and participate in the development and improvement of models in collaboration with the Laboratory of Process Modelling of CEA LITEN. During the thesis a collaboration with Pr. Dubarry's team from the University of Hawaii in the field of data processing based on the ICA (Incremental Capacity Analysis) method.

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Optimized coding technics for the design of deep neural network hardware accelerators

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Adéquation Algorithmes Architecture

01-09-2020

SL-DRT-20-0869

johannes.thiele@cea.fr

(.pdf)

Artificial neural network based approaches have significantly improved performance in many areas such as classification, segmentation, and so on. The effectiveness of this approach is well established and the number of future applications increases. However, due to their computational complexity and their memory need, these networks are difficult to embed on low power platforms. When porting these networks on embedded platforms, a large variety of hardware constraints have to be taken into account. To overcome these difficulties several research works have produced different techniques that allow to reduce memory and computation footprint of artificial neural networks: reduction of the number of parameters, low precision quantization, etc. This thesis aims to go further into the optimization by working on the data coding. On this thesis, we proposed to explore a new method by working directly on the information coding of the neural network. This coding method would aim to unify two existing coding models: the vector model and the spike model, while keeping in perspective the hardware implementation.

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Study of transport mechanisms of lithium in hybrid electrolytes for solid-state batterie

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Matériaux

01-10-2020

SL-DRT-20-0872

thibaut.gutel@cea.fr

(.pdf)

The replacement of liquid electrolyte by ionic conductive phase at solid state (polymer, inorganic or hybrid) is considered as the most promising way to increase electrochemical performances and safety of the next generation of lithium battery. However the improvement of ionic conductivity of these complex systems is still required. Indeed the understanding and modeling of the mechanisms which take place in lithium diffusion inside materials with various properties should be better known in order to develop and optimize solid-state battery. In this PhD, we propose to study a reference hybrid solid-state electrolytes formed by a dispersion of an inorganic material and a lithium salt inside a polymer matrix using approaches based on electrochemistry/characterization/simulation. Selectively labeled systems with 6Li/7Li isotopes will be electrochemically tested and analyzed with mass spectrometry (TOF-SIMS) and solid-state NMR in order to quantify the evolution of isotope ratio at local level and in the bulk in order to identify the transport mechanisms which occurs in these electrolytes with the help of physical model. Advanced characterization techniques used in this PhD will provide physical parameters as inputs for the model in order to predict electrochemical behavior of electrolyte media and consequently to propose some tools to select and modify materials and to optimize the formulation of hybrid electrolytes. Finally this work will lead to identify strategies to improve their performances (ionic conductivity and electrochemical stability).

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Understanding of the protective action of surface treatments on electrode materials

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Matériaux

01-09-2020

SL-DRT-20-0873

david.peralta@cea.fr

(.pdf)

Next generations of Li-ion batteries will have to increase the driving range of future electric cars. To reach high electrochemical performances, active materials are used close to their theoretical limits. Both electrochemical and chemical stabilities could be affected because the active material/electrolyte interface is very reactive and results in poor battery cycle life. This material/electrolyte interface is also important in the case of solid state batteries where materials surface has to be stabilized before the cell manufacturing process because some materials are not stable in air atmosphere. One of the most interesting strategy to overcome these issues consists of treating the electrode materials surface to limit side reactions before and during cycling. Several coatings (AlF3, Al2O3, MgO, MnO2?) reported in literature highlight that a thin passivation layer at the material surface can enhance the electrochemical behavior by limiting side reactions (ex: Al2O3) and/or by improving the power behavior (AlF3). Despite the number of scientific publications in this field, no clear explanation is provided why such a treatment can enhance both the electrochemical behavior and the stability of the resulting material. The selected student will work at the Battery Components Laboratory of CEA. This laboratory is dedicated to the synthesis and characterization of new battery materials. The PhD student will be in charge of developing new surface treatments and will have to perform several fine characterizations in order to highlight phenomena which happen at materials interface. Candidate has to be a master student and has to be specialized in material chemistry (synthesis and/or characterization).

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SAB bonding study for heteristructure elaboration

Département des Plateformes Technologiques (LETI)

Laboratoire

01-10-2020

SL-DRT-20-0874

frank.fournel@cea.fr

(.pdf)

This study aim is on the fundamental bonding of ultra high vacuum bonding done after ionic activation (SAB). One goal is to investigate the direct bonding mechanism including this specific bonding technic. All the characterization used to put in place the actual silicon direct bonding mechnisme will then be used to evaluate the SAB bonding. The huge bonding energy since room temperature could lead to very interesting impact on our direct bonding mechanism as well as on, for instance, the Smart Cut one. In parallel, the elaboration of heterostructure using SAB will be evaluated will the possibility to elaborate strain Germanium or Silicon thin film which could be very useful in optoelectronic.

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3D imaging module with integrated optics

Département d'Optronique (LETI)

Laboratoire Architecture Systèmes Photoniques

01-10-2020

SL-DRT-20-0876

laurent.frey@cea.fr

(.pdf)

3D sensing by capturing depth images, is a key function in numerous emerging applications such as facial recognition, augmented reality, robotics or drones. CEA targets the development of an innovative 3D sensing module, inspired from Lidar, and including various innovative components, from the coherent optical source to the photo-detector. The proposed PhD will focus on the definition of an integrated optics architecture coupled to an optical imaging system, optical simulation with internal code or commercial software, fabrication in micro-electronic clean-room, electro-optical characterization of individual components, computing of algorithms for signal or image processing, and demonstration of the whole system, for its miniaturization and integration for example in mobile devices such as a smartphone. The work will be performed in close collaboration with a research team that will develop in parallel a first version of the system in free space. A transfer to the industry is targeted in the end.

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Ultralow-loss SiNSOI integrated devices for high-rate, wavelength-multiplexed QKD

Département d'Optronique (LETI)

Laboratoire d'Intégration Photonique sur Silicium

01-10-2020

SL-DRT-20-0877

corrado.sciancalepore@cea.fr

(.pdf)

The main activities of this proposed PhD thesis will consist in the realization of silicon photonics structures for the improvement of Quantum Key Distribution (QKD) protocols. The final goals will tackle both main strategies currently employed for QKD, decoy state QKD and entanglement based QKD. Ultralow loss silicon photonics devices will be used to obtain functionalities that would be impossible or cumbersome using non integrated setups and for the convenience and reliability of operation that come from integration. Entanglement is a fundamental resource in quantum information and at the base of the most demanding protocols including device independent quantum cryptography. Room temperature, silicon integrated sources of entangled photon pairs are extremely important for the widespread adoption of quantum communication, yet despite many demonstrations in the past ten years a complete turn-key silicon source of entangled photon pairs is still lacking. In this second objective we will demonstrate such a source by integrating laser pump, source of photon pairs, and filtering and demultiplexing stages all on the same chip.

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Synthesis of wideband and compact antennas for the supergain and beam-forming

Département Systèmes (LETI)

Laboratoire Antennes, Propagation, Couplage Inductif

01-10-2020

SL-DRT-20-0878

antonio.clemente@cea.fr

(.pdf)

Directive compact antennas offer new opportunities for wireless applications in terms of spectral efficiency, reduced environmental impact and use modes. However, the conventional techniques for enhancing the directivity often lead to a significant increase of the antenna size. Consequently, the integration of directional antennas in small wireless devices is limited. This difficulty is particularly critical for the frequency bands below 3 GHz if objects dimensions are limited to a few centimeters. Super directive/gain compact antennas with beam-steering capabilities and operating on a wideband or on multi-bands are an innovative and attractive solution for the development of new applications in the field of the connected objects. In fact, the possibility to electronically control the antenna radiation properties is an important characteristic for the development of the future generation and smart communication systems. CEA LETI has a very strong expertise in the domain of super directive antennas. The recent works realized demonstrated the potentials of the super directive compact parasitic antenna arrays. The PhD will take place at CEA LETI Grenoble in the antennas and propagation laboratory. The main objectives of this project are: i) the development of analytical and numerical tools for the synthesis, design and optimization of super directive compact arrays with beam-steering capabilities; ii) the study of new elementary sources for compact antenna arrays; iii) the realization and experimental characterization of a super directive compact array with beam-steering capabilities.

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Mechanical simulation of PEMFC assembly

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Composants Pemfc

01-09-2020

SL-DRT-20-0882

jean-francois.blachot@cea.fr

(.pdf)

The aim of the PhD concerns ?the mechanical simulation of PEMFC stacks », which is a developing subject in the laboratory. Indeed, the researches of these last years focused on the development of components, on the one hand, more robust such as for example: more stable catalysts and reinforced membranes, which are on the other hand, getting thinner necessitating a more and more complex assembly. First studies were performed thanks to the COMSOL Multiphysics software, to facilitate the link with the associated fluididic simulation, they confirmed the interest of this topic. The candidate should continue to develop these works, from the accurate simulation of the materials that could present non linear behaviour, to the use of homogeneisation methods allowing to transfer local simulations to the scale of a stack. The candidate would also master the experimental measurements necessary to the validation of the modellings.

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Detection and location of faults in a multiconductor transmission line

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Fiabilité et Intégration Capteur

01-09-2019

SL-DRT-20-0890

moussa.kafal@cea.fr

(.pdf)

The proper functioning of a distribution network depends on the ability to quickly detect the occurrence of faults, such as discharges, short circuits or the penetration of moisture in the cables. If the nature of these defects depends on the application context, the techniques used to detect them depend essentially on the ability to request a cable with test signals, and to monitor the appearance of response signals that would testify to the existence of a modification in the cables. While this approach is clear in the case of standard cables consisting of two conductors, the case of Multiconductor cables remains more complex to deal with. Indeed, applying test signals to a pair of conductors typically causes parasitic excitation of nearby conductors, because of the electromagnetic coupling that connects them. This phenomenon can considerably complicate the interpretation of the results of a test, by creating an ambiguity in the identification of the faulty driver, because several drivers can couple with those actually under test. In this thesis, the coupling will be considered as an opportunity, because it allows to probe a larger number of drivers at the same time. The intrinsic ambiguity of such a proposition can be removed by repeating the tests on several pairs of conductors. It then seems interesting to define optimum choice strategies of drivers to test to cover the largest number of neighboring drivers, without testing all possible combinations. In this sense, this proposal is parsimonious, introducing the concept of effective test surface covered from a pair of conductors. A promising decision strategy for identifying a failing driver is provided by Bayesian tree and graph-based approaches. These tools make it possible to cross the information obtained in order to identify an explanatory model, here the faulty driver. Among the advantages of this approach we can count on their ability to integrate qualitative information, such as the typology of the defect, and to provide a result formulated in terms of probabilities associated with each possible scenario, thus qualifying the interpretation of results and to assess their reliability, unlike purely numerical methods. It will then be necessary to carry out a preparatory work, making it possible to evaluate the probability a priori of observing parasitic signals from a fault on a neighboring conductor. This work will be based on the study of line theory and will provide the link between the physical aspects of Multiconductor propagation and the observables considered during the tests.

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Study of embedded prognostic strategies in wired networks based on temporal neural networks

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Fiabilité et Intégration Capteur

01-09-2020

SL-DRT-20-0891

wafa.benhassen@cea.fr

(.pdf)

Whatever their fields of application, cables are very often victims of their operating environment. They often face aggressive conditions such as mechanical vibration, heat stress, moisture penetration, etc. These conditions favor the appearance of more or less serious defects ranging from a simple crack in the sheath to a cable break thus causing a malfunction of the system. In this context, the CEA LIST studies methods of diagnosis and prognosis of defects in cable networks based on the reflectometry method. The idea is to inject a test signal into the cable. Whenever it encounters an impedance discontinuity (i.e. a fault), some of its energy is returned to the injection point. The processing of the reflected signal subsequently makes it possible to detect and locate this defect. Despite the maturity of the reflectometry to detect a defect in a cable, it does not allow to determine the causes of the appearance of an incipient defect (ie damage of the shielding, radius of curvature, pinching, etc.) nor to predict its evolution in the future. The work of this thesis aims at developing new prognostic strategies for defects in wired networks. For this, the application of Machine Learning methods such as Artificial Neural Networks (ANN) on data from reflectometry sensors is a promising solution to solve this problem. It is in this context that the works of this thesis are inscribed.

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High speed wireline and optical communication at cryogenic temperature for quantum computing

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Intégration Silicium des Architectures Numériques

01-09-2020

SL-DRT-20-0892

yvain.thonnart@cea.fr

(.pdf)

The promise for a universal fault-tolerant quantum computer robust to relaxation and phase errors of qubits faces a major scaling challenge, with thousands to millions of qubits to control and measure to implement the necessary quantum error correction codes. The information to exchange between the quantum devices at cryogenic temperature and the room temperature instrumentation equipments needs data throughputs above 1 Terabit/s to achieve in a reduced power budget to limit self-heating. This PhD topic aims to propose and realize energy-efficient high-speed communication architectures and circuits leveraging optical fiber transmission between the cryostat and the ambient temperature. The targetted innovation is to design and implement cryo-electronic CMOS circuits in FDSOI technology to realize communication functions such as SerDes, clock recovery and silicon-photonic modulator and receiver drivers tightly coupled to the quantum devices. These works will be integrated in a large development effort for a quantum computing Accelerator architecture based on electron spins in silicon, led by a pluridisciplinary team of physicists, technologists, CMOS designers and hardware and software architects.

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Design and assessment of FD-SOI devices specially functionalized for uncooled IR imaging

Département d'Optronique (LETI)

Laboratoire d'Imagerie thermique et THz

01-10-2020

SL-DRT-20-0893

jyon@cea.fr

(.pdf)

Uncooled infrared focal plane array (U-IRFPA) microbolometer technology has opened the field of thermal imaging to various novel applications, such as automotive driving assistance, building automation, leisure, smartphone. These new applications are expected to grow rapidly to reach a large volume market. Firstly developed at CEA-LETI, microbolometer technology was then transferred to LYNRED (LYNRED by SOFRADIR & ULIS, www.lynred.com) in charge of its industrialization. However, the freshly expressed new commercial needs require an improvement of the technology based on some breakthrough developments, in particular to reduce the pixel pitch to 5µm, i.e. the ultimate size sets by the IR radiation diffraction. It is the framework of this doctoral study, which aims at developing a novel class of microbolometers, by the mean of a thermal micro-transducer based on a MOS technology on FD-SOI silicon thin film, whose performance is expected as a breakthrough with respect to thermistor-based current technology. Research work will cover both the architectural design of a new integrated IR sensor on silicon, its technological prototyping (on the Leti's 200mm silicon platform) and the finale evaluation of its performance. Basically, it means both design and achievement of a disruptive sensor which differs from a classical unitary MOS-FET transistor as it could features for example an active sensor made of several different devices, or even a smart sensor adjusting itself its sensor properties in standalone. At the end of the 3 years, the student will have led to an in-depth evaluation of the feasibility of this technology for uncooled IR imaging.

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biomass-based hydrochar for hard carbon production for Na-ion batteries

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Matériaux

01-09-2020

SL-DRT-20-0897

loic.simonin@cea.fr

(.pdf)

Na-ion batteries have been the subject of intense research in recent years. Indeed, the criticality of lithium, which has been debated for more than a decade, has led to the search for alternatives to this element as a charge carrier in batteries. From this point of view, research on M-ion systems (M= Na, K, Mg, Ca, etc.) is growing considerably with the Na-ion both as a leading figure and as the most successful system. At CEA, the activity is booming and has made it possible to select very promising active materials in terms of power capability, cyclability, etc. Among these, hard carbon presents remarkable anode performance in terms of specific capacity and service life. Nevertheless, its production cost, 2 to 3 times higher than that of graphite, is a barrier to its commercialization. This high cost is partly explained by the cost of the precursors traditionally used. In this context, the proposed PhD project aims to produce negative electrode materials for Na-ion batteries from wet biomass-based carbon (e.g. sewage sludge, paper industry residues, digestates, microalgae gasification residues, etc.). Most of these wet biomasses are difficult to valorize and constitute low-cost precursors, or even negative cost. First, the hydrothermal synthesis step will be optimized from a limited number of biomasses. Then, the link between the compositional properties of biomasses and then performance of hard carbon will be studied.

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Mid-IR digital holography

Département d'Optronique (LETI)

Laboratoire des Capteurs Optiques

01-10-2020

SL-DRT-20-0900

mathieu.dupoy@cea.fr

(.pdf)

Currently the challenge is to develop automation and non-invasive measurements to enhance early identification or diagnosis. The optical technologies are the label free methods to detect and identify the chemical composition of sample. Infrared spectroscopy is a widespread and reliable method to obtain a spectral fingerprint of sample based on absorption of mir-IR light. An optical platform has been developed to measure the absorption of light through the sample, combining quantum cascade laser (QCL) and bolometer matrix. The objective of the thesis is to explore the potential of Mid-IR digital holography in order to obtain information on the phase of the sample. The thesis will aim to choose the best optical configuration of interferometer and the implement it in conventional optics. After processing the images and extracting the information, a second task will be perform this function on an integrated optical component

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Distributed Memory-centric Computing architecture for AI applications, using advanced 3D and NVM Technologies

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Intégration Silicium des Architectures Numériques

01-09-2020

SL-DRT-20-0913

ivan.miro-panades@cea.fr

(.pdf)

With the revolution of AI applications, AI algorithms are getting more and more demanding in terms of computing and memory requirements, while it is envisioned that new devices implementing these AI features should be available at the ?edge?, meaning close to the final user (portable devices, automotive, IoT, etc) and not anymore only in the cloud. This implies very strong requirement in terms of memory capacity to enable learning at the edge with compliant energy efficiency. The PhD consists in proposing and exploring new Distributed Memory-centric Computing architecture for AI applications, using advanced technologies to overcome the current issues (memory capacity, memory bandwidth, energy per inference, and learning capability). Recent Non Volatile Memory (NVM) technologies and 3D integration technologies offer dense memory integration while bringing the memory closer to computing cores. The architecture challenge consists in defining the adequate system partitioning, the distributed communication mechanisms, the memory/computing ratios requirements, to in-fine obtain the targeted distributed memory centric computing architecture. The work will consist in architecture and application system exploration through system modeling, and may lead to a testchip to validate the proposed concept. The PhD will take place in an active collaboration between University of Stanford (CA, USA) and CEA (Grenoble, France).

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Pixel wise coded aperture for new acquisition paradigms in CMOS Image Sensors based on active illumination

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Circuits Intégrés, Intelligents pour l'Image

01-10-2020

SL-DRT-20-0917

arnaud.verdant@cea.fr

(.pdf)

Active illumination combined with image sensors bring the opportunity to extract a large amount of features about the observed scene that are generally not reachable to standard image acquisition approaches. This modality is now largely spread in industrial computer vision, consumer electronics and medical imaging applications. However, major challenges still need to be solved to increase the performances of such devices, and many associated research questions need to be addressed, with respect to the choices of the modulation and measurement strategy, the sensor architecture, or the signal processing techniques to employ for data analysis. The goal of this thesis is to jointly address those issues by first proposing a simulation framework aiming at finding the best trade-offs between light modulation and signal reconstruction approaches. Then, developing the system that will best fit to the derived specifications according to typical scene characteristics (ballistic or diffuse light behavior, depth range and resolution, ambient light levels, light source interferences?) will be addressed. This thesis will be structured in two main parts. The first part will tend to define an exploration framework based on a combination of physical modeling, physical measurements and deep learning approaches. Based on this tool, the second part will be dedicated to the development of an image sensor architecture using the issued specifications. The PhD student will benefit during his 3-years thesis of the expertise and the scientific excellence of the CEA Leti to attend objectives with a high level of innovation through international patents and publications. The dynamic and autonomous candidate will have a master or Engineer degree, specialized in electrical engineering and signal processing. A good knowledge of circuit design CAD and programming tools will be important (Cadence, Matlab, Python) and some basics in optics will be appreciated.

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In-situ visualization and quantification of microstructural evolutions in all-solid batteries

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Nanocaractérisation et Nanosécurité

01-10-2020

SL-DRT-20-0919

adrien.boulineau@cea.fr

(.pdf)

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Assessing the variability of operators' morphology for assembly tasks using virtual reality

Département Intelligence Ambiante et Systèmes Interactifs (LIST)

Laboratoire de Simulation Interactive

01-10-2020

SL-DRT-20-0920

vincent.weistroffer@cea.fr

(.pdf)

The aim of the thesis is to develop a tool for the evaluation of the feasability and the ergonomics of a task with operators having a different morphology than an operator performing the task in virtual reality. Two scientific questions will be addressed. The first problem consists in automatically identifying the characteristics of the task to perform (i.e. the important steps, the trajectories and/or the associated efforts), based on a limited number of demonstrations from operators using virtual reality. The second problem consists in transferring the task performance formerly identified to avatars (virtual humans) having different morphologies.

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Impact of micro-architecture on side-channel attack countermeasures

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Infrastructure et Ateliers Logiciels pour Puces

01-09-2020

SL-DRT-20-0921

nicolas.belleville@cea.fr

(.pdf)

The context of this thesis is the context of cyber-security for embedded systems and IoT. The thesis addresses the application of countermeasures by compilation against side-channel attacks exploiting power consumption or electromagnetic emissions, which represent a major threat against these systems. A leakage model can be used when applying countermeasures: it models how side-channel leakages are related to the program and the data being manipulated by the processor. An unfaithful model does not allow the countermeasure to be applied effectively. The models currently employed are insufficient since they do not take into account the micro-architecture of the components. Indeed, micro-architecture and in particular elements that are invisible at the assembly level (hidden registers or buffers) can cause leakages. The objective of this thesis is to study the impact of micro-architecture on the automated application of countermeasures against auxiliary channel attacks during compilation. A first axis is to study how to modify the way countermeasures are applied within the compiler to take into account precise leakage models that are micro-architecture aware, for example how to adapt the instruction selection or register allocation in the compiler depending on the leakage model. A second axis is to adapt the countermeasures themselves in order to better take into account the nature of the leakages, with the objective of improving the reduction of information leakage and thus improving the security/performance trade-off.

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Bio sensir using near field propagation of millimeter waves

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Architectures Intégrées Radiofréquences

01-10-2020

SL-DRT-20-0933

frederic.hameau@cea.fr

(.pdf)

In the context of new bio-medical applications, we propose to use solutions from the radio-frequency domain, namely using millimeter wave systems, which had to radiate with nearfield antenna. Depending on the antenna neighborhood, the behavior of the radiated wave changes with its frequency and amplitude. This PhD aims to detecte physiological parameters using this signature of the environnement at different wavelength, signal amplitude and even signal shape (chirp). This physiological parameter could be the sweat, the hartbeat, melanoma, but not only. Target frequency could be from 20GHz to 120GHz which are easy for CMOS integration. From an existing study, the PhD student will have to developpe an accurate solution, which could be based on the antenna impedance variation due to the environement (Power Amplifier output impedance modification tracking) or the analysis of the reflected signal thought a polar receiver (radar mode).

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Intensification of carbon dioxide sequestration through microalgae photosynthesis

DPACA (CTReg)

Autre DPACA

01-10-2020

SL-DRT-20-0948

gatien.fleury@cea.fr

(.pdf)

Numerous scientific studies, led in particular by IPCC, have shown that anthropogenic greenhouse gas emissions are responsible for global warming of Earth's atmosphere. Due to the tremendous volumes emitted worldwide annually (more than 30 billion metric tons), CO2 is considered to be one of the main contributors to global warming. Among the methods for sequestering CO2, photosynthesis is particularly attractive, since it makes it possible to create different products through to the capture of solar energy together with CO2. This PhD thesis will focus on the use of microalgae photosynthesis for CO2 sequestration. After a bibliography step which will allow the student to better understand the equilibria at stake and the corresponding equations, first part of the work will focus on the development of an analytical model allowing to simulate different operating conditions by a multidisciplinary approach (in particular fluid mechanics, chemistry and biology). After validation of this model on simple experiments made up with a strain of reference, an innovative culture device (photobioreactor) making it possible to intensify the mass transfers of a gas phase enriched in C02 towards microalgal biomass could be proposed, developed and tested.

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Capture and recovery of CO2 by electroreduction

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des Eco-procédés et EnVironnement

01-10-2020

SL-DRT-20-0955

vincent.faucheux@cea.fr

(.pdf)

Electrochemical conversion of CO2 (from industry or directly from air) is a way to produce fuels or chemicals from intermittent electricity. In addition, micro-algae culture is a process that could replace petrochemicals, by producing biofuels while completing the anthropogenic carbon cycle. The combination of these two sectors in a new hybrid concept would improve the performance of microalgae production processes upstream of bioenergy applications. Indeed, the culture of micro-algae in the presence of light and an organic substrate formate based, produced by electrolysis of CO2 allows accelerated growth. Several challenges must be addressed to reach such technology with high-energy yields: catalytic in order to maximize the production of formate and integrative in order to maximize the yield of photo bioreactors by using the whole solar spectrum (by coupling photovoltaic generation of electricity and photosynthetic generation of biomass according to the absorbed wavelengths). The first objective of the thesis is to develop a catalytic system associated with an advantageous liquid media based on the use of ionic liquids whose CO2 absorption capacity is much greater than for water. Measurements will permit to establish material and energy balances by coupling the reduction of CO2 with the oxidation of water. Acquired knowledges will then be transferred to the cases of physiological fluids, compatible with the generation of formate and the production of lipids by micro algae. The second objective consists in improving the energy efficiency of biomass production within a high-yield photo bioreactor (PBR) which will use the whole solar spectrum, by coupling photovoltaic generation of electricity and photosynthetic generation of biomass. Semi-transparent photovoltaic systems that can be integrated into PBR and optically optimized to promote the production of electricity and the growth of micro-algae will be developed. As part of this thesis project, the goal is to develop an electrolyzer for the production of formate in physiological electrolyte which can be supplied by the above-mentioned photovoltaic panel.

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Innovative Piezoelectric Materials elaborated by Pulsed Laser Deposition (PLD)

Département des Plateformes Technologiques (LETI)

Laboratoire

01-09-2020

SL-DRT-20-0970

florian.dupont2@cea.fr

(.pdf)

In this thesis work, the PhD student will first evaluate the conditions to promote epitaxial growth of innovative materials like LNO. The objective is to create conditions promoting the required crystalline orientations for RF filters application. PLD deposition technique will be used to deposit this ?template? and/or complex oxides on silicon, with wafer diameters compatibles with the standards of microelectronic industry. This work will benefit from a large variety of physico-chemical characterization techniques available in LETI platforms, including Xray Diffraction, XPS, Auger, HRTEM to evaluate interfacial structure, and piezoelectric measurements. In a second time, those layers will be integrated into simplified structure tests to evaluate the impact of their properties on final device performances.

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