Spatial inhomogeneity and temporal dynamics of a 2D electron gas in interaction with a 2D adatom gas

Fabien Cheynis (1) , Stefano Curiotto (1) , Frédéric Leroy (1) , Pierre Müller (1)

1 CINaM - Centre Interdisciplinaire de Nanoscience de Marseille

Fundamental interest for 2D electron gas (2DEG) systems has been recently renewed with the advent of 2D materials and their potential high-impact applications in optoelectronics. Here, we investigate a 2DEG created by the electron transfer from a Ag adatom gas deposited on a Si(111) 3 × 3-Ag surface to an electronic surface state. Using low-energy electron microscopy (LEEM), we measure the Ag adatom gas concentration and the 2DEG-induced charge transfer. We demonstrate a linear dependence of the surface work function change on the Ag adatom gas concentration. A breakdown of the linear relationship is induced by the occurrence of the Ag adatom gas superstructure identified as Si(111) 21 × 21-Ag only observed below room temperature. We evidence below room temperature a confinement of the 2DEG on atomic terraces characterised by spatial inhomogeneities of the 2DEG-induced charge transfer along with temporal fluctuations. These variations mirror the Ag adatom gas concentration changes induced by the growth of 3D Ag islands and the occurrence of an Ehrlich-Schwoebel diffusion barrier of 155 ± 10 meV.

Domaines: Matière Condensée [cond-mat]; Science des matériaux [cond-mat.mtrl-sci]

Fabien Cheynis, Stefano Curiotto, Frédéric Leroy, Pierre Müller. Spatial inhomogeneity and temporal dynamics of a 2D electron gas in interaction with a 2D adatom gas. Scientific Reports, 2017, 7 (1), pp.10642. ⟨10.1038/s41598-017-10300-6⟩. ⟨hal-01651465⟩