Core level photoemission studies of the sulphur terminated Ge(100) surface

Abstract

A core level photoemission spectroscopy study of the deposition of sulphur on the germanium (Ge(100)) surface has been performed. The sulphur is deposited from an electrochemical cell onto the clean Ge surface at room temperature in ultra-high-vacuum (UHV). The Ge surface dimers are broken and the sulphur terminated surface displays a (1×1) reconstruction. Analysis of the core level spectra reveal that all four Ge oxidation states are present indicating that a non-ideal surface termination has been formed. Annealing of the sulphur terminated surface to 200°C further promotes the formation of a S–Ge reacted phase which desorbs at higher annealing temperatures, re-establishing the clean surface spectrum. The results are consistent with recent studies indicating that the thermal desorption of the sulphur layer causes a surface etching process to occur.