T-4 SITE ADSORPTION OF TL ATOMS IN A SI(111)-(1 X 1)-TL STRUCTURE, DETERMINED BY LOW-ENERGY ELECTRON DIFFRACTION ANALYSIS

Abstract

A (1 x 1) structure formed on Si(111)7 x 7 by thallium (Tl) atom deposition and subsequent annealing has been determined by tensor low-energy electron diffraction (LEED) analysis. Six adsorption sites of Tl atoms on a bulk-truncated surface were examined. The on-top site adsorption of Tl, which was previously deduced from scanning tunneling microscopy images and attributed to the monovalent nature of Tl, is excluded in this LEED analysis. it is concluded that the T-4 site is the most optimal. Since the surface forms the (1 x 1) periodicity, the T-4 site adsorption is highly anomalous among metal deposited Si(111) surfaces.