Description du sujet de thèse

Ferroelectrics with spontaneous switchable electric polarizations are important candidates for realizing nonvolatile random-access memory. Their bistable states with moderate switching barriers may enable memories with room-temperature robustness at nanoscale. A successful combination of ferroelectricity and semiconductors will be highly desirable in the coming era of ferroelectronics, which enables ferroelectric field-effect transistor, merging logic, and memory functionalities in a single device, overcoming the interconnect bottleneck in von Neumann architecture.
Studies on two-dimensional (2D) van der Waals ferroelectrics offer a possible solution to the well-known epitaxial compatibility problem with the substrate: If the media of ferroelectricity are 2D materials with atomic thickness, also with a clean van der Waals interface that does not require lattice match with substrates, they should be exempt from the interfacial issues for device integration. Additionally, many of them are high-mobility semiconductors (over 1,000 cm2·V−1·s−1) like phosphorene, MoS2, and InSe. Similar studies have even been extended to 1D/0D ferroelectricity. Nevertheless, successful trials in searching for 2D van der Waals ferroelectrics were once limited to very few cases: The electric polarizations of lV–VI monolayers are strictly in-plane, and the more favorable vertical ferroelectricity was experimentally confirmed in only CuInP2S6 and In2Se3 down to the monolayer limit. After all, the vertical ion displacements for ferroelectric switching are limited in a confined 2D layer.

The research activities will be centered on the structural and electronic properties two-dimensional (2D) van der Waals ferroelectrics via photoluminescence/Raman, SHG and Angle-Resolved Photoemission Spectroscopy.
The PhD candidate should present strong experimental aspects (2D material transfer), a serious physical background (solid state physics, semi-conductor) and good computer skills for data treatment and analysis.

Contexte de travail

The work will be conducted at the Centre de Nanosciences and Nanotechnologies (C2N) in Palaiseau (France). The C2N is a joint research lab between Université Paris-Saclay and the Centre National de la Recherche Scientifique (CNRS) which is home to about 200 research staff and 200 PhD and post-doc.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

Laser risks, chemical risks.