Research

VW-Spin: Engineering of excitonic and spin-valley properties of transition metal dichalcogenides monolayers in van der Waals heterostructures

Research project selected under the 2016 call for proposals

Principal Investigator :

Cedric ROBERT ()
LPCNO

Type of project : Disruptive Project

Date (start/end) : 2017 - 2019

     

       

Sketch of a van der Waals heterostructure graphene/hBN/WSe 2 monolayers used to study the effect of a perpendicular electric field (red arrow) on the physical properties of the WSe 2 monolayer.

Abstract

For more than ten years, the research exploring the electronic and optical properties of atomically flat, two-dimensional (2D) materials, has led to new device concepts based on original physical properties. Far beyond graphene, the library of existing 2D materials is currently extending to a wide range of semiconductors, insulators, metals and superconductors. Taking advantage of each material properties, the stacking of diverse 2D layers to build van der Waals heterostructures , should open the way to a new class of devices with atomically flat active regions with potential applications in optoelectronics, spintronics, flexible electronics or photovoltaics.

Among the various families of 2D materials, semiconductor transition metal dichalcogenide (TMDC) materials MX 2 (where M stands for Mo or W and X stands for S , Se or Te ) are expected to play a main role in vdW heterostructures based devices. Indeed, when thinned down to the monolayer limit, these materials exhibit several exciting properties:

  1. a direct optical band gap ranging from visible to near infrared wavelengths
  2. a strong light matter interaction governed by very robust excitons
  3. an access to both spin and valley degrees of freedom due to the lack of crystal inversion symmetry and large spin-orbit coupling

The goal of this project is to develop innovative van der Waals heterostructures to study the excitonic and the spin-valley properties of TMDC monolayers. This will constitute a technological breakthrough toward the development of future devices.

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