Scientific direction Development of key enabling technologies
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PostDocs : selection by topics

Engineering science >> Solid state physics, surfaces and interfaces
3 proposition(s).

Simulation of semimetal nanowires

Département Composants Silicium (LETI)

Laboratoire d'Intégration des Composants pour la Logique

01-11-2017

PsD-DRT-18-0004

jean-pierre.colinge@cea.fr

The candidate's mission will be: ? Simulation using ab-initio tools of the structure of bismuth nanowire bands of different diameters (from 1 nm to 10 nm). ? Extraction of parameters as effective masses, density of states, band offsets for these nanowires. ? Implementation of these parameters in a NEGF simulator to simulate bismuth nanowire transistors with variable diameter. ? Ab-initio simulation of the bismuth-dielectric nanowire interface and study of various elements of chemical passivation. ? This work will be done in collaboration with LETI / DCOS / SCME / LSIM (Philippe Blaise) ? The candidate will interact with an experimental team that will produce the simulated devices and will help to supervise one or more doctoral students, in collaboration with IMEP. ? The candidate will interact with the LTM to help predict the properties of the grid bismuth-insulator interface and implement the IMEP results in the simulator.

Charge to spin conversion in HgTe topological insulators

Département d'Optronique (LETI)

Laboratoire des Matériaux pour la photonique

01-01-2018

PsD-DRT-18-0025

philippe.ballet@cea.fr

The intrinsic spin-momentum locking of Dirac fermions at the surface or interface of topological insulators opens the path towards novel spintronic effects and applications. Strained HgTe/CdTe is a model topological insulator and a very good candidate to design and demonstrate new spintronic devices exploiting the very large charge to spin conversion efficiency expected for such 2D systems. This postdoc position aims at realizing the first demonstration of the direct charge to spin conversion in topological HgTe nanostructures and use this demonstration as a building block for spin based logic elements.

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).

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