All opportunities

Offers : 26

Modeling silicon-on-insulator quantum bit arrays

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Start date : 1 November 2019

offer n° PsD-DRF-19-0091

A post-doctoral position is open at the Interdisciplinary Research Institute of Grenoble (IRIG, formerly INAC) of the CEA Grenoble (France) on the theory and modeling of arrays of silicon-on-insulator quantum bits (SOI qubits). This position fits into an ERC Synergy project, quCube, aimed at developing two-dimensional arrays of such qubits. The selected candidate is expected to start between October and December 2019, for up to three years.

Many aspects of the physics of silicon qubits are still poorly understood, so that it is essential to support the experimental activity with state-of-the-art modeling. For that purpose, CEA is actively developing the “TB_Sim” code. TB_Sim relies on atomistic tight-binding and multi-bands k.p descriptions of the electronic structure of materials and includes, in particular, a time-dependent configuration interaction solver for the dynamics of interacting qubits.

The aims of this post-doctoral position are to improve our understanding of the physics of these devices and optimize their design, and, in particular,

– to model spin manipulation, readout, and coherence in one- and two-dimensional arrays of SOI qubits.

– to model exchange interactions in these arrays and assess the operation of multi-qubit gates.

The candidate will have the opportunity to interact with the experimental teams from CEA/IRIG, CEA/LETI and CNRS/Néel involved in quCube, and will have access to data on state-of-the-art devices.

  • Keywords : Theoretical physics, Solid state physics, surfaces and interfaces, Theoretical Physics, INAC, MEM
  • Laboratory : INAC / MEM
  • CEA code : PsD-DRF-19-0091
  • Contact : yniquet@cea.fr

FDSOI technology scaling beyond 10nm node

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Start date : 1 November 2018

offer n° PsD-DRT-18-0074

FDSOI (Fully-Depleted Silicon On Insulator) is acknowledged as a promising technology to meet the requirements of emerging mobile, Internet Of Things (IOT), and RF applications for scaled technological nodes [1]. Leti is a pioneer in FDSOI technology, enabling innovative solutions to support industrial partners.

Scaling of FDSOI technology beyond 10nm node offers solid perspectives in terms of SoC and RF technologies improvement. Though from a technological point of view, it becomes challenging because of thin channel thickness scaling limitation around 5nm to maintain both good mobility and variability. Thus, introduction of innovative technological boosters such as strain modules, alternative gate process, parasitics optimization, according to design rules and applications, become mandatory [2].

The viability of these new concepts should be validated first by TCAD simulations and then implemented on our 300mm FDSOI platform.

This subject is in line with the recent LETI strategy announcement and investments to develop new technological prototypes for innovative technology beyond 28nm [3].

The candidate will be in charge to perform TCAD simulations, to define experiment and to manage them until the electrical characterization. The TCAD simulations will be performed in close collaboration with the TCAD team. The integration will be done in the LETI clean room in collaboration with the process and integration team. Candidate with out-of-the-BOX thinking, autonomy, and ability to work in team is mandatory.

[1] 22nm FDSOI technology for emerging mobile, Internet-of-Things, and RF applications, R. Carter et al, IEEE IEDM 2016.

[2] UTBB FDSOI scaling enablers for the 10nm node, L. Grenouillet et al, IEEE S3S 2013.

[3]https://www.usinenouvelle.com/article/le-leti-investit-120-millions-d-euros-dans-sa-salle-blanche-pour-preparer-les-prochaines-innovations-dans-les-puces.

  • Keywords : Engineering science, Electronics and microelectronics - Optoelectronics, DCOS, Leti
  • Laboratory : DCOS / Leti
  • CEA code : PsD-DRT-18-0074
  • Contact : claire.fenouillet-beranger@cea.fr

AlGaN/GaN HEMTs transfert for enhanced electrical and thermal performances

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Start date : 1 April 2018

offer n° PsD-DRT-18-0060

Due to their large critical electric field and high electron mobility, gallium nitride (GaN) based devices emerge as credible candidates for power electronic applications. In order to face the large market needs and benefit from available silicon manufacturing facilities, the current trend is to fabricate those devices, such as aluminum gallium nitride (AlGaN)/GaN high electron mobility transistors (HEMTs), directly on (111) silicon substrates. However, this pursuit of economic sustainability negatively affects device performances mainly because of self-heating effect inherent to silicon substrate use. New substrates with better thermal properties than silicon are desirable to improve thermal dissipation and enlarge the operating range at high performance.

A Ph.D. student in the lab. has developed a method to replace the original silicon material with copper, starting from AlGaN/GaN HEMTs fabricated on silicon substrates. He has demonstrated the interest of the postponement of a GaN power HEMT on a copper metal base with respect to self heating without degrading the voltage resistance of the component. But there are still many points to study to improve the power components.

Post-doc objectives : We propose to understand what is the best integration to eliminate self-heating and increase the voltage resistance of the initial AlGaN/GaN HEMT. The impact of the component transfer on the quality of the 2D gas will be analyzed.

The same approach can be made if necessary on RF components.

Different stacks will be made by the post-doc and he will be in charge of the electrical and thermal characterizations. Understanding the role of each part of the structure will be critical in choosing the final stack.

This process will also be brought in larger dimensions.

This post-doc will work if necessary in collaboration with different thesis students on power components.

  • Keywords : Engineering science, Materials and applications, Thermal energy, combustion, flows, DCOS, Leti
  • Laboratory : DCOS / Leti
  • CEA code : PsD-DRT-18-0060
  • Contact : julie.widiez@cea.fr

Nano-silicon/graphene composites for high energy density lithium-ion batteries

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Start date : 1 May 2018

offer n° PsD-DRF-18-0052

This postdoctoral fellowship is part of the Graphene Flagship Core 2 H2020 european project (2018-2020) on the energy storage applications of graphene. In lithium-ion batteries, graphene associated to nanostructured silicon in a proper composite helps increase the energy capacity. Indeed graphene wraps silicon, reducing its reactivity with electrolyte and the formation of the SEI passivation layer. It also maintains a high electrical conductivity within the electrode.

The study will compare two technologies: graphene-silicon nanoparticles and graphene-silicon nanowires. The former composite, already explored in the above mentioned project, will be optimized in the present study. The latter is a new kind of composite, using a large scale silicon nanowire synthesis process recently patented in the lab. The postdoc will work within two laboratories: a technological research lab (LITEN) with expertise in batteries for transportation, and a fundamental research lab (INAC) with expertise in nanomaterial synthesis.

The postdoc will synthesize silicon nanowires for his/her composites at INAC. Following LITEN know-how, she/he will be in charge of composite formulation, battery fabrication and electrochemical cycling. He/she will systematically compare the electrochemical behavior of the nanoparticle and nanowire based silicon-graphene composites. Comparison will extend to the mechanism of capacity fading and SEI formation, thanks to the characterization means available at CEA Grenoble and in the European consortium: X-ray diffraction, electronic microscopy, XPS, FTIR, NMR spectroscopies. She/he will report her/his work within the international consortium (Cambride UK, Genova Italy, Graz Austria) meetings.

A 2-year post-doctoral position is open.

PhD in materials science is requested. Experience in nanocharacterization, nanochemistry and/or electrochemistry is welcome.

Applications are expected before May 31st, 2018.

  • Keywords : Engineering science, Materials and applications, Ultra-divided matter, Physical sciences for materials, INAC, SyMMES
  • Laboratory : INAC / SyMMES
  • CEA code : PsD-DRF-18-0052
  • Contact : pascale.chenevier@cea.fr

Tunnel Junction for UV LEDs: characterization and optimization

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Start date : 1 September 2018

offer n° PsD-DRT-18-0047

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).

  • Keywords : Solid state physics, surfaces and interfaces, DOPT, Leti
  • Laboratory : DOPT / Leti
  • CEA code : PsD-DRT-18-0047
  • Contact : guy.feuillet@cea.fr
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