(a) sketch of a vicinal surface . (b) One of Phophorene allotropes. (c) STM picture of atomic arrangement.

Laboratoire: MPQ (Matériaux et Phénomènes Quantiques), Université Paris Cité & CNRS
Adress: Bâtiment Condorcet – 10 Rue A. Domon et L. Duquet – 75013 Paris
Internship/PhD supervisor: Yann Girard
Tel: 01 57 27 62 99
e-mail: yann.girard@u-paris.fr

Scientific project:

In the field of 2D materials, such as graphene, silicene, or stanene, phosphorene is a recently investigated novel candidate for peculiar electronic properties. Due to its high carrier mobility and moderate band gap, black phosphorus thin films have attracted great interest in recent years for potential applications in several fields. Further theoretical predictions have also suggested that a single layer of phosphorus atoms, called phosphorene, should present a huge number of possible two-dimensional (2D) allotropes. Each of them has modulable properties according to its atomic structure, size, or shape of low-dimensional phosphorene nanostructures. One of the most promising routes for the epitaxial growth of new 2D allotropes is to take advantage of the surface stresses induced by lattice mismatches with metallic surfaces of different crystallographic orientations, such as Au (111) or (100). This strategy has already been successfully applied to stabilize new structures.

The goal of this PhD thesis is to discover new phases with innovative properties, using a bottom-up strain engineering technique to master the formation of various phosphorene 2D-allotropes. The originality of this proposal is to investigate even further the role played by the surface stress in gold sample using specifically their vicinal variants. A significant part of the master thesis will be dedicated to the preparation of the substrate surfaces and the subsequent P deposition by thermal evaporation in a dedicated UHV chamber. The characterization of the morphology and crystal structure will be achieved by room temperature scanning tunneling microscopy (STM) and LEED/Auger Electron Spectroscopy (AES) measurements. Electronic properties of these new materials will be investigated using low temperature (4 K) measurements by scanning tunnelling spectroscopy (STS) and ARPES (colaboration with LPS-Orsay).

The PhD thesis is funded by ANR project : ANR-22-CE09-0022, 2DPhostrainE. See also the EDPiF website to submit your application there.

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