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

PhD : selection by topics

Engineering science >> Materials and applications
10 proposition(s).

Development of innovative piezoelectric micromachined ultrasound transducer (pMUT) for automotive applications

Département Composants Silicium (LETI)

Laboratoire Composants Micro-Capteurs

01-09-2018

SL-DRT-18-0471

bruno.fain@cea.fr

The potential use of piezoelectric micromachined ultrasound transducers (pMUT) within smartphones, tablets and connected devices have raised a growing interest during the last years to build new fingerprint sensors and achieve better, low-power range-finder. To meet the specific needs of these new applications, the performances of pMUT have to be increased. This Ph.D. thesis aims at building new devices to cope with the requirements of automobile applications. The conception, the fabrication and the characterization of the pMUT will be investigated by the Ph.D student. The conception will be based on both analytical approaches and finite elements modelling (ANSYS, Comsol Multiphysics). The fabrication process will be achieved within the 8 inches MEMS Platform of CEA-LETI with the strong support of the CEA teams. The characterization, mostly probe measurements at the wafer level, will confirm and refine the models. The relevance of the devices for the targeted applications will be evaluated. For this purpose, the Ph.D. student is expected to have strong background in mechanics. He will tackle both scientific and technological challenges. He should be an autonomous team player.

Télécharger l'offre (.zip)

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

DM2I (LIST)

Laboratoire Capteurs et Architectures Electroniques

01-10-2018

SL-DRT-18-0611

guillaume.laffont@cea.fr

LCAE 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.

Télécharger l'offre (.zip)

Use of parsimony and machine learning for the real time simulation of realistic nondestructive testing signals

Département Imagerie Simulation pour le Contrôle (LIST)

Laboratoire Simulation et Modélisation en Electro-magnétisme

01-10-2018

SL-DRT-18-0628

roberto.miorelli@cea.fr

Many sophisticated numerical solvers are nowadays available for the simulation of complex configurations in the field of non-destructive testing (NDT). This complexity can come from the piece 3D geometry, for products of additive manufacturing processes, or from its composition, for composite structures or complex heat-treated steel, for instance. Beside these aspects, which motivate many efforts of theoretical modelling and numerical implementation, other environmental factors may have a strong impact on the physical NDT signals. Among these effects, one can cite other physical effects like shifts of temperature, electromagnetic perturbations coming from neighbouring machines or more simply additional physical effects that the model does not account for. These effects translate into an uncertainty on the measurements themselves (in terms of repeatability for instance) and consequently in a mismatch between simulated signals and experiments. Such discrepancy can lead to misleading conclusions and estimations. Defining in a general way the discrepancy between theoretical models and real experiments is not an easy task. This component of the signal, which can be labelled as ?noise?, depends on so many factors and practical conditions that it cannot be easily modelled or described theoretically. The proposed PhD subject proposes an approach to address the issue of characterizing this noise component and incorporating it into the simulation process. The tools implemented will focus on NDT inspections of metallic or composite structures by means of ultrasonic or electromagnetic methods. The proposed strategy relies both on advanced concepts of statistical learning theory (supervised and unsupervised learning, dictionary learning and deep learning) and on advanced numerical simulation tools (finite element, boundary element and fast semi-analytical methods) developed at CEA LIST for the simulation of NDT. First, by comparing experimental data and simulations, statistical learning algorithms will allow to determine characteristic features describing the discrepancy between them. Then, contributions based on these descriptors will complement the theoretical signals coming from the physical model in order to get a simulation that compares to experiment with better accuracy, taking into account the particular conditions of experimental acquisitions. When coupled with metamodels, acting as real time substitute of the physical model, then real-time realistic simulators can be obtained. The expected results of this ambitious thesis work are numerous. First of all, realistic models can be obtained and adapted to case-dependent industrial conditions, provided that sufficient amount of experimental data is available. On can thus expect a better performance of online diagnostics and parameters estimations. Then, such models can be used for training purposes as they can in real time generate realistic signals corresponding to various imaginary flaws affecting the material under test. Lastly, such models will enhance the estimation of confidence levels associated to NDT techniques, as they will provide a more accurate description of the real signals variability.

Télécharger l'offre (.zip)

Phase-Change Memory for high density Storage Class Memory applications

Département Composants Silicium (LETI)

Laboratoire de Composants Mémoires

01-10-2018

SL-DRT-18-0691

gabriele.navarro@cea.fr

Nowadays, the need of a data storage infrastructure allowing Big Data processing requires memory devices with improved performance. The objective of this PhD is the development of innovative Phase-Change Memory (PCM) devices to target Storage Class Memory applications (SCM) that require higher programming speed and endurance. To achieve this goal, the phase change material engineering becomes fundamental, in particular exploring new alloys capable of higher crystallization speed and higher stability. The candidate will contribute to the following tasks: development and electrical characterization of PCMs based on innovative materials, also co integrated with new BackEnd selectors developed in LETI, from single device analysis to full matrix statistics; physico-chemical characterization of the different alloys by resistivity measurements, XRD, FTIR, TEM etc.; multi-physical simulations to correlate the device performances with the material properties. In addition, the student will contribute to industrial projects, and will interact with experts at the international level in the field of the phase change materials.

Télécharger l'offre (.zip)

CIPV: Car-Integrated-PhotoVoltaics. Development of specific photovoltaic modules for vehicle integration

Département des Technologies Solaires (LITEN)

Laboratoire Modules Photovoltaïques silicium

01-10-2018

SL-DRT-18-0797

julien.gaume@cea.fr

Photovoltaic technologies increased significantly with a production largely dominated by rigid and flat crystalline silicon-based modules (over 90% market share), intended for residential applications or solar farms. In the case of specific applications, where integration and weight are predominant, thin and flexible PV modules have been developed. The market for autonomous and hybrid vehicles has significantly grown in the recent years. Despite this growth, few solutions integrating photovoltaic panels have been proposed. The Laboratory of Silicon Photovoltaic Modules of the CEA-Liten at INES has acquired a knowledge in the development of innovative photovoltaic PV modules for specific applications. This knowledge will be applied to the development of PV modules specifically dedicated to the application of autonomous or hybrid vehicles. The objectives of the thesis will be: - a state of the art establishment on the application of PV as a direct source of energy for electric cars. - Identification of technological locks and technical tracks to solve them. - Estimatation/modeling the energy production of different surfaces and the effects on the autonomy of the car, according to several scenarios. - Sizing, realization and characterization of innovative photovoltaic modules prototypes in indoor environment thanks to all the PV Modules platform. Integration into an electric demonstration vehicle. - studying PV & battery system interaction to optimize the electric charging.

Télécharger l'offre (.zip)

Van der Waals epitaxy of CdTe on 2D materials

Département d'Optronique (LETI)

Laboratoire des Matériaux pour la photonique

01-10-2018

SL-DRT-18-0843

philippe.ballet@cea.fr

2D materials nowadays attract a great amount of research because of their unique properties directly derived from their graphene-like electronic structure and crystalline organization. These materials have strong in-plane chemical bounds while extremely weak, van der Waals type, out-of-plane interaction describing them a 2D sheets of monolayer material. 2D material epitaxy on conventional 3D semiconductors may thus occur without any lattice parameter mismatch strain. The opposite is also true when depositing a 3D onto a 2D. The PhD work consists in studying in details these new epitaxial systems with the proposal of realizing the strain free epitaxial growth of photovoltaics CdTe or infrared sensitive HgCdTe on 2D layers. These materials (2D and 3D) will be grown by molecular beam epitaxy allowing for an in-situ control of the interface. The growth mode of 3D(CdTe)/2D and 2D/3D(HgCdTe) will be first independently studied with the goal of providing a full 3D(CdTe)/2D/3D(HgCdTe) heterostructure where the 3D(CdTe) will promote, through the very thin 2D, the crystalline structure and orientation for the ultimate growth of HgCdTe. Inserting a weakly bonded 2D material also offer promising new functions by enabling the HgCdTe layer to be detached and transferred onto another substrate opening the way towards new optoelectronic applications. The thesis scientific environment will be brought to a broader range by considering the availability and proximity of the nano-characterization platform (CEA-PFNC) where skilled teams and last generation of equipment are dedicated to revealing the chemical nature and crystallographic structure of the epitaxial stacks.

Télécharger l'offre (.zip)

GaN doping by ion implantation and innovative annealing

Département Technologies Silicium (LETI)

Autre Laboratoire

01-10-2018

SL-DRT-18-1001

frederic.mazen@cea.fr

In response to societal needs for the preservation of the environment and alternative energies, the CEA is developing an activity on the production of power devices. For this, the CEA has chosen a breakthrough technology based on the use of Gallium Nitride, which should make it possible to overcome the theoretical limits of silicon. However, GaN-based technologies are much less mature than those based on the use of silicon. The objective of this thesis work will be to contribute to the implementation of the technological GaN doping brick by ion implantation and to seek innovative annealing allowing to anneal at very high temperature in order to activate the dopants without damaging the structure of the Gan on Si wafer. Despite significant progress in recent years, the realization of effective doping processes and the understanding of the associated mechanisms remain significant challenges. This work will involve the development of ion implantation processes and innovative heat treatments that will be evaluated and compared to reference processes. A particular focus will be on understanding and modeling the impact of defects created by the implantation process and their evolution during thermal treatments on the activation of dopants. For this, many physicochemical, structural, optical and electrical characterization techniques (SIMS, TEM, RBS / MEIS, X-ray Diffraction, PL, ECV, Tomographic Atomic Probe, Hall Effect ...) will be implemented or developed. The final objective of the work, in connection with the integration teams, will be to develop doping processes adapted to the specifications of the envisaged devices.

Télécharger l'offre (.zip)

Electronic Additive Manufacturing for Smart Materials

DLORR

01-10-2018

SL-DRT-18-1019

manuel.fendler@cea.fr

Additive manufacturing offers the opportunity to revolutionize the fabrication of printed circuits, whose architecture is similar to a 2D + Z vertical stack. Indeed, the photolithography and chemical deposition processes necessary for the realization of the tracks, are not only harmful for the health and the environment, but also do not allow the direct functionalization of 3D objects. At the time of the Internet of Things, intelligence is getting deeper and deeper into designs, and additive manufacturing gives a unique opportunity to value the inter strata obtained by 2D + Z slicing. Thus we propose to leave the manufacture of printed circuits from chemical baths, in favor of an addition of conductive material by 3D printing.

Télécharger l'offre (.zip)

¨Preamorphization via ion implantation for salicide optimization

Département Technologies Silicium (LETI)

Laboratoire

01-09-2018

SL-DRT-18-1064

frederic.mazen@cea.fr

? Pre-amorphization implantation (PAI) for salicidation has been introduced during the last years to limit leakage junction, to optimize Schottky Barrier Height (SBH) and contact resistance of ultra-shallow junction by controlling roughness and limiting agglomeration of silicide. It seems also a good way to increase contact stability and yield, for example, by limiting silicidation close to the FD-SOI MOS transistor channel (piping defect). To take benefit and integrate this new step in the next CMOS technology generation and beyond, it seems necessary to accelerate development and understanding on this item. ? The thesis objectives will be to develop a process and to acquire a well understanding of the different interaction between pre-amorphization implantation conditions (species, energy, dose, etc.), and NiSi (or NiSiGe) formation in terms of metallurgical structure, roughness, and agglomeration. Interaction with dopant junction will be also studied. In parallel, piping evolution with PAI could be explored on morphological wafers. At the end, PAI physics understanding and impact on NiSi material will be discussed. Electrical performance, contact resistance, silicide stability and yield will be the figure of merit of developments. This work will have to permit a reduce development time to integer this new process in the next transistor Technology. Thesis will be achieved in collaboration with CEA-LETI and IM2NP. ? Based on the state of the art, and technological constraint, student will propose experiment, and characterization needs. He will be in charge of defining morphological and electrical test vehicle (short-loop) with adapted process flow, and following realization in clean room. Standard physical and electrical characterization as DRX in temperature, TEM (EDX, cross-section), SIMS, TLM and Rs measurement will be used. Thanks to IM2NP experience in Atom Probe Tomography (APT), 3D chemical analysis of NiSi will be a key to exhibit composition, segregation effect and understanding correlation between silicidation, PAI and contact parameters. TCAD simulation could be also used to define implantation conditions.

Télécharger l'offre (.zip)

Water management in direct bonding

Département Technologies Silicium (LETI)

Laboratoire

01-10-2018

SL-DRT-18-1070

frank.fournel@cea.fr

Direct bonding is now used in many applications. Very recently, at CEA Grenoble, it has been shown that water can soak in a non-annealed direct bonding interface as well as to be removed from it. As water is one of the main parameter in hydrophilic direct bonding, controlling and accurately understand this phenomenon is very important for all hydrophilic direct bonding and not only for the Silicon/Silicon bonding. This study aim will be to study in detail the water management inside a direct bonding interface following different ways: A first part of the study will be to find a way to isolate the bonding interface. It is mandatory for all the accurate characterization of the direct bonding in order to have stable samples. It is also very interesting for many applications for which the edges are important and would like to get rid of this phenomenon. A second part of the study will be to continue the characterization of the water low dynamic at an annealed direct bonding interface. It will be also interesting to evaluate this flow during the annealing. The in or out dynamic will be evaluate regarding the bonding energy reached by the interface at the different annealing temperature. A last part of the study will be to evaluate accurately the water amount at the hydrophilic direct bonding interface of ?stable? samples. Varying this water quantity, a link will be done with the direct bonding energy and the possible defectivity which could appear under certain conditions. The student will be formed to all the needed technology used in direct bonding (chemistry, CMP, bonding, thermal annealing?) as well as all its usual characterization techniques (Infrared spectroscopy, acoustic microscopy, anhydrous bonding energy, XRR?)

Télécharger l'offre (.zip)

Voir toutes nos offres