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

PostDocs : selection by topics

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Optimisation of the Micromegas detector for neutron radiography

Département Métrologie Instrumentation et Information (LIST)

Laboratoire Capteurs et Architectures Electroniques

01-06-2021

PsD-DRT-21-0024

adrien.sari@cea.fr

A postdoctoral position of 12 months of duration is available at CEA Paris-Saclay in the frame of the OMNIS project, which aims at adding new features to a detector based on the Micromegas technology, that is to say: real-time neutron radiography capabilities under high radiation constraints. The postdoctoral researcher will participate to the next developments and optimization of the Micromegas detector for neutron radiography applications. First, the postdoc will work on the characterization, understanding and optimization of the prototype. This study will involve both Monte-Carlo simulation and experimental tests in laboratory in order to estimate the effect of several parameters (gas composition, neutron converter, drift gap, electric field configuration, etc.) and to assess its performances for neutron radiography. In view of enhancing both the spatial resolution and the gamma suppression, evaluation of various camera operation modes will be part of the work done in this project. The results of this work will be the basis for the design of a larger prototype dedicated to neutron radiography applications.

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Hybrid CMOS / spintronic circuits for Ising machines

Département Composants Silicium (LETI)

Laboratoire d'Intégration des Composants pour la Logique

01-01-2021

PsD-DRT-21-0025

louis.hutin@cea.fr

The proposed research project is related to the search for hardware accelerators for solving NP-hard optimization problems. Such problems, for which finding exact solutions in polynomial time is out of reach for deterministic Turing machines, find many applications in diverse fields such as logistic operations, circuit design, medical diagnosis, Smart Grid management etc. One approach in particular is derived from the Ising model, and is based on the evolution (and convergence) of a set of binary states within an artificial neural network (ANN).In order to improve the convergence speed and accuracy, the network elements may benefit from an intrinsic and adjustable source of fluctuations. Recent proof-of-concept work highlights the interest of implementing such neurons with stochastic magnetic tunnel junctions (MTJ). The main goals will be the simulation, dimensioning and fabrication of hybrid CMOS/MTJ elements. The test vehicles will then be characterized in order to validate their functionality. This work will be carried out in the frame of a scientific collaboration between CEA-Leti and Spintec.

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Multi-scale modeling of the electromagnetic quantum dot environment

Département Composants Silicium (LETI)

Laboratoire de Simulation et Modélisation

01-03-2021

PsD-DRT-21-0027

helene.jacquinot@cea.fr

In the near future, emerging quantum information technologies are expected to lead to global breakthroughs in high performance computing and secure communication. Among semiconductor approaches, silicon-based spin quantum bits (qubits) are promising thanks to their compactness featuring long coherence time, high fidelity and fast qubit rotation [Maurand2016], [Meunier2019]. A main challenge is now to achieve individual qubit control inside qubit arrays. Qubit array constitutes a compact open system, where each qubit cannot be considered as isolated since it depends on the neighboring qubit placement, their interconnection network and the back-end-line stack. The main goal of this post-doctoral position is to develop various implementation of spin control on 2D qubit array using multi-scale electromagnetic (EM) simulation ranging from nanometric single qubit up to millimetric interconnect network. The candidate will i) characterize radio-frequency (RF) test structures at cryogenic temperature using state-of-the-art equipment and compare results with dedicated EM simulations, ii) evaluate the efficiency of spin control and allow multi-scale optimization from single to qubit arrays [Niquet2020], iii) integrate RF spin microwave control for 2D qubit array using CEA-LETI silicon technologies. The candidate need to have a good RF and microelectronic background and experience in EM simulation, and/or design of RF test structures and RF characterization. This work takes place in a dynamic tripartite collaborative project between CEA-LETI, CEA-IRIG and CNRS-Institut Néel (ERC ?Qucube?).

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Simulation and electrical characterization of an innovative logic/memory CUBE for In-Memory-Computing

Département Composants Silicium (LETI)

Laboratoire d'Intégration des Composants pour la Logique

01-01-2020

PsD-DRT-20-0029

francois.andrieu@cea.fr

For integrated circuits to be able to leverage the future ?data deluge? coming from the cloud and cyber-physical systems, the historical scaling of Complementary-Metal-Oxide-Semiconductor (CMOS) devices is no longer the corner stone. At system-level, computing performance is now strongly power-limited and the main part of this power budget is consumed by data transfers between logic and memory circuit blocks in widespread Von-Neumann design architectures. An emerging computing paradigm solution overcoming this ?memory wall? consists in processing the information in-situ, owing to In-Memory-Computing (IMC). However, today's existing memory technologies are ineffective to In-Memory compute billions of data items. Things will change with the emergence of three key enabling technologies, under development at CEA-LETI: non-volatile resistive memory, new energy-efficient nanowire transistors and 3D-monolithic integration. At LETI, we will leverage the aforementioned emerging technologies towards a functionality-enhanced system with a tight entangling of logic and memory. The post-doc will perform electrical characterizations of CMOS transistors and Resistive RAMs in order to calibrate models and run TCAD/spice simulations to drive the technology developments and enable the circuit designs.

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Developement of relaxed pseudo-substrate based on InGaN porosified by electrochemical anodisation

Département des Plateformes Technologiques (LETI)

Laboratoire des Matériaux pour la photonique

01-03-2021

PsD-DRT-21-0035

carole.pernel@cea.fr

As part of the Carnot PIRLE project starting in early 2021, we are looking for a candidate for a post-doctoral position of 24 months (12 months renewable) with a specialty in material science. The project consists in developing a relaxed pseudo-substrate based on III-N materials for µLEDs applications, especially for emission in red wavelength. The work will focus on developing an InGaN-based epitaxy MOCVD growth process, on an innovative substrate based on electrochemically anodized and relaxed materials. He (She) will have characterize both the level of relaxation of the re-epitaxied layer and its crystalline quality. These two points will promote the epitaxial regrowth of an effective red LED. The candidate will be part of the team, working on the PIRLE project, will be associated to the work on red LED growth and its optical and electro-optical characterizations.

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Development of a modular multi-detector instrumentation for the measurement of atomic and nuclear parameters

Département Métrologie Instrumentation et Information (LIST)

Laboratoire de Métrologie de l'Activité

01-04-2020

PsD-DRT-21-0039

benoit.sabot@cea.fr

The LNE PLATINUM project (PLATFORM OF MODULAR NUMERICAL INSTRUMENTATION) aims to develop a modular platform, in order to test new instrumentation using two or more detectors in coincidence. The principle implemented in this project is based on the simultaneous detection of interactions taking place in two different detectors, by collecting information on the type of particle and its energy (spectroscopy). This principle is the basis for absolute measurements of activity or active continuous background reduction systems to improve detection limits. But it also allows the measurement of parameters characterizing the decay scheme, such as internal conversion coefficients, X-ray fluorescence yields or angular correlations between photons emitted in cascade. Thanks to its expertise in atomic and nuclear data, the LNHB has noted for many years the incompleteness of decay schemes for certain radionuclides. These schemes, established at the time of evaluation from existing measured data, sometimes present inconsistencies or poorly known transitions, in particular in the presence of highly converted gamma transitions or very low intensity (for example, recent studies on 103Pa, 129I and 147Nd have revealed such inconsistencies). It therefore appears important for LNHB to better master the technique of coincidence measurement, taking advantage of the new possibilities in terms of data acquisition and time stamping to provide additional information on decay scheme and contribute to their improvement.

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