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Offers : 111

Photonic spiking neurmorphic network

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Start date : 1 October 2019

offer n° SL-DRT-19-0942

Neuromorphic networks for signal and information processing have acquired recently a renewed interest considering the more and more complex tasks that have to be solved automatically in current applications: speech recognition, dynamic image correlation, rapid decision processing integrating a plurality of information sources, behavior optimization, etc… Several types of neuromorphic networks do exist and, among them, the spiking type (SNN), that is, the one closest in behavior to the natural cortical neurons. SNN are the ones who seem to be able to offer a best energy efficiency and thus offer scalability. Several demonstration have been made in this domain with electronic circuits and more recently with photonic circuits. For these, the dense integration potential of silicon photonics is a real advantage to create complex and highly connected circuits susceptible to lead to complete demonstrations. The PhD goal is to exploit a photonics spiking neuromorphic network architecture based on pulsed (Q-switched) lasers interconnected by a dense and reconfigurable optical network on chip mimicking the synaptic weights. A complete laser, neuron then circuit model is expected with, in the end, the practical demonstration of an application in mathematical data processing (to be defined).

  • Keywords : Engineering science, Mathematics - Numerical analysis - Simulation, Optics - Laser optics - Applied optics, DOPT, Leti
  • Laboratory : DOPT / Leti
  • CEA code : SL-DRT-19-0942
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Large-scale atomistic modeling of complex materials and application to advanced memories

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Start date : 1 October 2019

offer n° SL-DRT-19-0953

Among next generation nonvolatile memories (NVM), Phase Change memory (PCM) is the most mature one. CEA Leti is currently working on the development of this technology in collaboration with industrial partners. However several technological issues require a fine understanding of the underlying physical mechanisms at the atomic scale. Simulations using large scale molecular dynamics (MD) are particularly suitable to investigate these phenomena but require accurate interatomic potentials to describe the potential energy surface (PES). In the past decade, much progress has been made in the development of interatomic potentials using machine learning techniques to describe complex systems.

The goal of this PhD is to develop novel atomistic potentials based on machine learning methods and implement these methods in parallel simulation codes. These potentials will then be used to carry out large scale molecular dynamics simulations on systems containing a few thousands of atoms and applied to PCM memories problems. In particular, these simulations will allow to study the phase change and thermal properties of these materials.

Required skills:

o Background in physics and chemistry or related fields

o Good programming skills using C, C++ and Python

o Knowledge of Linux and parallel computing is desirable

o Previous experience with machine learning techniques is a plus

  • Keywords : Physical chemistry and electrochemistry, Solid state physics, surfaces and interfaces, DCOS, Leti
  • Laboratory : DCOS / Leti
  • CEA code : SL-DRT-19-0953
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Development of an LCD SLM in IPS configuration for AR / VR applications

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Start date : 1 November 2019

offer n° SL-DRT-19-0941

Today, the field of display is increasingly oriented towards applications such as augmented reality headphones (HMD) or head-up vision (HUD. In general, these devices use a micro-screen combined with an optical system for projecting an image on a specific surface in the case of an HUD, or directly on the eye in the case of an HMD. These devices have to provide an image with a very high resolution, all on a very wide angle of view. To meet these two issues, the optics needed is expensive and take too much place which increases the difficulty of integration for a mobile system such as the helmet. To solve this problem an intermediate solution exists, it is to use a system composed of an SLM (phase modulation) integrated into a so-called adaptive optical system. Furthermore, the transmissive feature of the SLM is mandatory and only the transmissive LCD microstructures, by acting on the phase and / or the polarization of the light, can find a wavefront corrector function for adaptive optics.

Adaptive optics projects include, for example, compact, high-resolution, high-resolution lenses based on the concept of eye function (Foveation), where only the part of the useful field is highly defined by acting on the correction of the wavefront via the integrated SLM in the optics.

Previous work has shown that this kind of object requires a technology using complex micro-electronics bricks based on the CMOS report on transparent substrate to obtain transmissive screens.

Our last theoretical study on the subject showed that the LCD screen configuration called IPS for In-Plane Switching, could be adapted to meet our needs. This configuration offers a lot of advantages including that of being easier to implement.

The proposed work is part of a new project in which the first phase will consist of simulating, with specific software, the evolution of the liquid crystal according to the different pixel design and electrode design to define the optimal geometry of the crystal liquid cell. If possible, preference will be given to structures where the liquid crystal does not twist. At the end of this study, the second phase of the project will include the complete realization of a screen with a passive matrix while taking into account the concept of the optimised cell. Finally, to measure the performance of the test cells and the final SLM obtained, the development and implementation of an optical and addressing bench for electro-optical characterization will also be requested.

  • Keywords : Engineering science, Electronics and microelectronics - Optoelectronics, Optics - Laser optics - Applied optics, DOPT, Leti
  • Laboratory : DOPT / Leti
  • CEA code : SL-DRT-19-0941
  • Contact :

III-V materials etch process development for power device application

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Start date : 1 September 2019

offer n° SL-DRT-19-0574

Formation of the two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructrures is the key-point for successful development of GaN-based power-electronics such as High Electron Mobility Transistors (HEMT) and diodes. Plasma-etching steps are considered as critical in fabrication for such devices.

The aim of this thesis is to understand the etch mechanism of III-V materials using traditional etch chemistry and its impact on the film damage.

An atomic layer etching (ALE) process developed at LETI will also be studied. This ALE process consists in etching the III-V material with cyclic steps. The first step is a chlorine based process to chemically modified the film at its surface, then an argon plasma is performed to selectively remove the modified layer.

The goal of the thesis is to develop and characterize these plasma etch processes. This understanding of plasma surface interaction function of the etch chemistry will be studied on CEA-LETI etch tools using complementary useful characterization techniques like XPS, Tof SIMS, TEM-EELS…

  • Keywords : Engineering science, Electronics and microelectronics - Optoelectronics, DTSI, Leti
  • Laboratory : DTSI / Leti
  • CEA code : SL-DRT-19-0574
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Transparent electrodes based on silver nanowires-nanocellulose: from fundamental aspects to device integration

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Start date : 8 April 2019

offer n° 2019-1

A phD position is offered between LMGP and LGP2 laboratories. The appointment has a fixed duration of 36 months, starting 01/10/2019.

You will be hired in the framework of a Regional project (2018-2023) called “Eternité” and dealing with research and development devoted to optically transparent materials and electrical conductors that has attracted growing interest in recent years for many applications. These are a key technological element for a large number of devices such as solar cells, efficient lighting (LEDs, OLEDs), touch screens, smart windows, transparent heating films, etc. The objectives of the ETERNITY project are to design and develop transparent electrodes that are: i / efficient (i.e. the most transparent and conductive possible); ii / stable through the production of nanocomposites via an innovative thin film deposition technique (either a thin oxide layer or the use of nanocellulose); iii / flexible (thanks to the use of metal nanowires (MNW) and nanocellulose which are ductile) on flexible substrates (especially polymers), iv / low cost and finally v / integrable within devices whose economic potential is strong and in full development and for which many industrial partners are present at both regional and national levels. The partners LMGP and LGP2 have independently developed in recent years specific expertise on stable and efficient electrodes based on silver nanowires (LMGP [1,2]) and AgNW/nanocellulose hybrids composites (LGP2 [3,4]). The combination of these two complementary laboratories will allow a good synergy to obtain efficient and durable transparent electrodes and thin films whose integration will easily be the object of collaborations with the industrial sector. The actions carried out in this PhD project concern the development of materials for the fabrication of these nanocomposites, their characterization and their physical modelling. Their integration into real devices will also be performed. This Thesis offers a good trade-off between fundamental and experimental aspects. The candidate will get precious knowledge and skills in physics, nanomaterial sciences and nanocellulose. The LMGP/LGP2 house state of the art experimental equipment to fabricate AgNW networks and nanocellulose with adapted tools for their physical characterizations.

Related references:
[1] T. Sannicolo, M. Lagrange, A. Cabos, C. Celle, J.-P. Simonato, D. Bellet, Small, 12 (2016) 6052;
[2] T. Sannicolo, N. Charvin, L. Flandin, S. Kraus, D. T. Papanastasiou, C. Celle, J. Simonato, D. M. Rojas, C. Jiménez, D. Bellet, ACS Nano (2018), 12, 4648;
[3] F. Hoeng, A. Denneulin, G. Krosnicki, J. Bras, J . of Mat. Chem. C 46 (2016) 10945;
[4] F. Hoeng, A. Denneulin, N. Reverdy-Bruas, G. Krosnicki, J. Bras, Applied Surf. Science 394 (2017) 160.

Research profile & skills (required / highly desirable): We are looking for a highly motivated student with a master degree in materials science or physics/chemistry, and who is interested to work in an inter-disciplinary project. Interpersonal skills, dynamism, rigor and teamwork abilities will be appreciated. Candidates should be fluent in both oral and written English.

Scientific environment:
The candidate will work within the LMGP (Materials and Physical Engineering Laboratory) in the FunSurf group and the LGP2 (Laboratory of Pulp and Paper Science and Graphic Arts) in the MatBio and FunPrint groups. Located in the heart of an exceptional scientific environment, both LMGP and LGP2 offer the applicant a rewarding place to work.

LMGP Web Site: LGP2 Web Site:

Salary: Pay scale of a fixed term post as a G-INP Researcher: 2315 €/month (gross salary, net salary: – 20%)

Application procedure: Please send motivation letter, CV, list of scientific publications and the contact information of a reference person (with e-mail & phone number) to:

Daniel Bellet: (04 56 52 93 37);
Julien Bras : (04 76 82 69 15) ;
Aurore Denneulin: (04 76 82 69 28) ;
David Muñoz-Rojas : (04 56 52 93 36).

Closing date for applications: 22th of April 2019

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