Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 67: Focus Session: Unoccupied States by Inverse Photoemission II

O 67.4: Vortrag

Mittwoch, 11. März 2026, 16:00–16:15, WILL/A317

Inverse photoemission studies of unoccupied electronic states of various Si(111)-based surfaces and interfaces — Younal Ksari, Hela Mrezguia, and •Jean-Marc Themlin — CNRS, Aix-Marseille Univ. University of Toulon, Marseille, France

We operate in Marseille an angle-resolved inverse photoemission (ARIPES) setup working in the isochromat mode. To illustrate the potential of this highly surface-sensitive technique, we give a comparative overview of the unoccupied part of the electronic structure of several Si(111)-based interfaces as revealed by ARIPES, from the hydrogenated H:Si(111) to 2D silicene monolayers grown on passivated Si(111) substrates.

The H-saturated (1x1) termination of Si(111) solely reveals bulk conduction band states. Upon segregation (B) or adsorption (H, As, Au) of foreign atoms on Si(111), specific surface states appear, leading to insulating (H, As, B) or metallic (Au) interfaces.

According to LEED, the adsorption of  1 ML of Si on the √3×√3)R30^∘ reconstructed Au- and B- substrates leads to the formation of a non-covalently bound Si bilayer, alias silicene, which adopts the symmetry of the passivated substrates. Specific unoccupied electronic states appear on each substrate, with dispersions profiles which do not exhibit a √3×√3)R30^∘ symmetry, small overall bandwidths and large bandgaps (resp. > 2 eV and > 1 eV), suggesting important correlation effects.

Keywords: Angle-resolved inverse photoemission spectroscopy; Unoccupied electronic surface states; Si(111) reconstructions; silicene