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

PostDocs : selection by topics

Cryogenic Analog Front-End for Quantum Computing

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

01-02-2018

PsD-DRT-18-0041

gael.pillonnet@cea.fr

Quantum engineering is a rapidly evolving novel domain in device technology, boosted by the recent progress in semiconductor quantum bits (QuBits) and by the major opportunity to combine the quantum device with dedicated electronics of conventional CMOS technology working at low temperatures (= 4 K). The ultimate goal of the research related to the proposed post-doc will be the development of silicon-based systems containing many QuBits and versatile electronics based on mature industrial technology, in order to facilitate the massive introduction of quantum processors. Nowadays state-of-the-art experiments on low-temperature quantum devices use electronic components at room temperature, but the future development of integrating many QuBits together complicates the device control with the multiplication of data lines. Minimal power dissipation and noise characteristics will be the challenging key elements to control a large number of QuBits. At CEA Grenoble, we have developed the first semiconductor QuBit fully realized on a CMOS 300-mm foundry that uses the spins of holes in Si as quantum state. The subject of the post PhD is aimed to build the electronics needed nearby the QuBit at low temperatures, using industrial CMOS technology (FDSOI 28nm) compatible with Silicon Qubits. The post PhD will be asked to develop his competence in the quantum physics of QuBits, the modelling of transistor parameters at low temperatures, and the design and measurement of analogue electronics, with the main task in developing and testing CMOS circuitry at low temperatures.

Diamond membrane based microdosimetric system for radiation quality assurance in hadron therapy

DM2I (LIST)

Laboratoire Capteurs Diamants

01-03-2019

PsD-DRT-19-0042

michal.pomorski@cea.fr

The Diamond Sensors Laboratory of CEA-LIST has twenty years of experience in diamond material synthesis including R&D on diamond-based sensors and radiation-detection devices. The INSERM-funded (2018-2020) DIADEM collaboration proposes to develop a new tissue-equivalent diamond-based micro-dosimeter with associated electronics, to obtain precise measurements of lineal energy distributions in hadron-therapy clinical conditions with high rates and high spatial resolution. Interdisciplinary experimental techniques, such as nano- and microfabrication, device characterization under ion nuclear microprobes micro-electronic and electronic developments are going to be employed for diamond micro-dosimeter prototyping. The performance of final prototypes will be evaluated with clinical hadron beams leading to first step for the implementation in radiobiological numerical models. The position: ? MC simulations of clinical proton/carbon beams interactions with matter, to benchmark experimental response of the micro-dosimeter prototypes ? participation in beamtimes for devices testing with clinical beams and parcticle microbeams at accelerator facilities ? participation in fabrication process of the devices (surfaces preparation, thin layer deposition, photolithography) Requirements: ? PhD in physics/medical physics or equivalent ? knowledge of solid-state particle detectors, associated electronics and signal processing, possibly including some experience at accelerator facilities ? knowledge of relevant Monte Carlo simulation programs ? verbal and written communication in English (French would be additional asset) ? knowledge of simple printed circuit boards design and semiconductors simulation software would be an asset Conditions: A one-year postdoctoral contract starting preferably from March-April 2019. Salary and benefits are commensurate with those of CEA organization. Classification is based upon candidate's qualification and assigned duties.

Symbolic learning for processes optimization

DM2I (LIST)

Laboratoire d'Analyse des Données et d'Intelligence des Systèmes

01-03-2019

PsD-DRT-19-0045

laurence.boudet@cea.fr

In the context of a R&D platform on symbolic artificial intelligence (knowledge-based systems), we would like to develop machine-learning capacities. One of the interests of such systems is to be able to explain their decisions, in line with GDPR which is applicable from May 2018. After a bibliographic study, the candidate will propose and develop evolution of existing methods or a new one for rule induction in presence of numerical or symbolic (categorical) variables. These algorithms will be applied to the prediction of the link between physical parameters of material elaboration (temperature, pressure, etc.) and desired technical features (such as resistivity). Results obtained will be compared with other classical techniques of machine learning. Furthermore, inducted rules will be evaluated by experts in material elaboration. We will be able to answer to the question: Does AI approach generate new knowledge? Two other laboratories will provide data and will make experiments during the project. They will be available for describing their knowledge. Thus, machine-learning and knowledge-modeling approaches will be compared.

Tunnel Junction for UV LEDs: characterization and optimization

Département d'Optronique (LETI)

Laboratoire des Matériaux pour la photonique

01-09-2018

PsD-DRT-18-0047

guy.feuillet@cea.fr

Besides existing UV lamps, UV LEDs emitting in the UV-C region (around 265 nm) are considered as the next solutions for cost efficient water sterilization systems. But existing UV-C LEDs based on AlGaN wide band gap materials and related quantum well heterostructures still have low efficiencies which precludes their widespread use in industrial systems. Analysing the reasons of the low efficiencies of present UV-C LEDs led us to propose a solution based on the use of a Tunnel Junction (TJ) inserted within the AlGaN heterostructure diode. p+/ n+ tunnel junctions are smart solutions to cope with doping related problems in the wide band gap AlGaN materials but give rise to extra tunneling resistances that need to be coped with. The post-doctoral work is dedicated to understanding the physics of tunneling processes in the TJ itself for a better control of the tunneling current. The post-doctoral work will be carried out at the ?Plate-Forme de Nanocaractérization? in CEA/ Grenoble, using different optical, structural and electrical measurements on stand-alone TJs or on TJs inserted within LEDs. The candidate will have to interact strongly with the team in CNRS/CRHEA in Sophia Antipolis where epitaxial growth of the diodes will be undertaken. The work is part of a collaborative project named "DUVET" financed by the Agence Nationale de la Recherche (ANR).

Low temperature process modules for 3d coolcube integration : through the end of roadmap

Département Composants Silicium (LETI)

Laboratoire d'Intégration des Composants pour la Logique

01-03-2019

PsD-DRT-19-0048

claire.fenouillet-beranger@cea.fr

3D sequential integration is envisaged as a possible solution until the end of CMOS roadmap. Different process modules have been developped @ 500°C for planar FDSOI technology in a gate first process. However, regarding bottom transistor level stability in CoolcubeTM integration, and yield consideration, the need to reduce further the top transistor temperature down to 450°C should be explored. The post-doc will have in charge the development of specific technological modules at low temperature both 500°C and 450°C for FDSOI planar devices to acquire a solid knowledge in low temperature CMOS process integration. The specific low temperature gate module will be addressed on planar devices. The threshold voltage modulation will also be studied. The work will be performed in collaboration with the technological platform process of LETI for the low temperature modules development. The electrical characterization in collaboration with the characterization laboratory and the TCAD simulations team of LETI.

Feasability study and development of models towards SPICE-simulation of silicon Qubit quantum circuits

Département Composants Silicium (LETI)

Laboratoire de Simulation et Modélisation

01-08-2019

PsD-DRT-18-0056

sebastien.martinie@cea.fr

The Compact / SPICE model is the link between the development of technological bricks and circuit design. The model purpose is to accurately reproduce the experimental characteristics essential to digital, analog and mixed circuit design. But today we need deeper investigation to set up the specifications of models for such device, in order to provide adequate tools to help circuit designers building up quantum circuits. The main challenge is to be able to describe the quantum behavior of this architecture. It will also be necessary to study if this behavior must be described via the physical quantities (eg electronic spin, energy level ...) or by logical quantities (quantum state, matrix of transformation, ...). It will also be necessary to take into account the compatibility between the mathematical formalism and the standard tools of compact modeling (through Verilog-A description). Following recent experimental research activities (between CEA and CNRS) concerning the first demonstration of hole spin qubit on SOI, we propose first to investigate how to model such device through macro modeling approach where SET compact model, inclusion of magnetic spin degeneracy and management of RF excitation are main steps. The challenges in regards to literature are inclusion of magnetic field in SET model, description of resonant tunneling, RF excitation of SET and reproduction of Rabi oscillations.

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