Laboratoire de Physique et Chimie des Nano-objets

Institut National des Sciences Appliquées
135 avenue de Rangueil, 31077 TOULOUSE CEDEX 4 - FRANCE
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Main research topics

Our activities are part of the research efforts on spin electronics and quantum technologies that are subject of strong international competition.

Our investigations on the excitonic and optical properties of two-dimensional materials based on transition metal dichalcogenides have greatly increased. We have recently made some important advances, notably on the measurement of the exciton binding energy, exciton fine structure (dark and bright states), the characteristics of the excited states, the dielectric screening effects, the radiative recombination dynamics , Auger effects, spin / valley relaxation mechanisms ...

In addition to the stationary or time-resolved optical spectroscopy measurements that are the specialty of the team, the novelty here was the development of sample production benches and the manufacture of devices. These efforts have resulted in very high quality samples and a very fast process between physical ideas, manufacturing and measurement.

We are also continuing our extensive studies on spin properties in several directions:

(a) Electrical spin injection or detection in III-V ferromagnetic / semiconductor hybrid structures (Spin-LED or Spin-photocurrent) with the first devices operating without external magnetic field;

(b) Spin-dependent recombination effects in GaAsN or Gallium-implanted GaAs-type materials, particularly with the demonstration of highly original electron-nuclei coherent spin oscillations;

(c) Spin-orbit engineering and its consequences on spin dynamics in GaAsBi / GaAs structures;

(d) Optical orientation and spin dynamics in semiconductors IV: Ge or GeSn on silicon.

In parallel, the expertise acquired in the team is valued in more applied research, in collaboration with public or industrial partners. These research contracts concern in particular: optical telecommunications (band structure engineering for semiconductor amplifiers with Nokia Bell Labs, III-V Lab and APEX Technologies); electronic devices for space (study of the effects of irradiation via the development of ultrafast laser irradiation benches with the SME TRAD); nanomaterials for photovoltaics and photocatalysis (Cu2ZnSnS4 and WSe2 with CIRIMAT in Toulouse).

Electrical injection and detection of spin polarized currents at Ferromagnetic metal /Semiconductor interfaces

a) Electrical spin injection Electrical spin injection through Schottky interfaces Co/n-doped AlGaAs, Co/ n-doped GaAs, and through interfaces based on insulating tunnel barriers Co/Al2O3/GaAs, Co/Al2O3/AlGaAs and CoFe/MgOGaAs, CoFeB/MgO/GaAs Spin injection in quantum wells GaAs/AlGaAs (...)

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Etude des propriétés de Spin des matériaux à base de nitrures fortement dilués : GaAsN massif et puits quantique InGaAsN/GaAs

Collaborations : V. Kalevich , E. Ivchenko , A. Shiryaev , A. Egorov, A.F.Ioffe Phisico-Technical Institute, Politekhnicheskaja, S.Petersburg , Russia JC Harmand LPN CNRS, Marcoussis Technique : Photoluminescence résolue en temps et en polarisation (ps), photoconductivité résolue en (...)

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Etudes des propriétés de spin de nouveaux matériaux à Grands Gaps pour la Spintronique : boîtes quantiques de GaN (cubique ou wurtzite) et ZnO massif.

a) Contrôle de la polarisation en spin des excitons dans de structure p-i-n à base de boîtes quantiques wurtzite InGaN/GaN par application d’un champ électrique externe. b) Etude de la dynamique de spin dans les boîtes quantiques cubique GaN/AlN Collaboration : H. Mariette, Intitut Néel (...)

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Etudes des propriétés Optiques et de Spin dans les boîtes quantiques semi-conductrices

a) Interactions entre spins d’électrons et spin nucléaires dans des boîtes quantiques uniques d’InAs/GaAs (mode de croissance Stranski-Krastanow) et GaAs/AlGaAs (croissance par « dropplet epitaxy ») Objectifs : Manipulation du spin d’un électron en interaction avec 10^5 spins nucléaires dans une (...)

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Nouveaux Matériaux Semi-conducteurs pour les télécommunications Optiques, le Spatial et le Photovoltaïque

Collaborations : Télécommunications : Alcatel-Thales III-V Lab (Marcoussis) ; France Télécom R&D (Lannion) ; ENST (Paris) ; IEMN (Lille) Spatial : CNES Photovoltaïque : ONERA, EDF Technique : Modélisation par méthode kp, Photoluminescence résolue en temps (ps), photocourant, Mesures de (...)

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Study of excitonic and spin-valley properties in transition metal dichalcogenide (TMDC) monolayers

CONTEXT. Layered materials are known for centuries. Nevertheless, the potential of these materials has been re-considered during the past decade thanks to the investigation of individual layers obtained by mechanical or chemical exfoliation. When thinned down to one monolayer, these materials (...)

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