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

PhD : selection by topics

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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

New computing paradigms, circuits and technologies, incl. quantum (.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

Additive manufacturing, new routes for saving materials (.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

Emerging materials and processes for nanotechnologies and microelectronics (.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

Emerging materials and processes for nanotechnologies and microelectronics (.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

Health and environment technologies, medical devices (.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

Additive manufacturing, new routes for saving materials (.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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