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

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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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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

Communication networks, IOT, radiofrequencies and antennas (.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

Emerging materials and processes for nanotechnologies and microelectronics (.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

Emerging materials and processes for nanotechnologies and microelectronics (.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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