Coverage Dependent Structural Change in Tetrahydrothiophene Adsorbed on Ge(100) Surface

Abstract

Studies on germanium have attracted significant attention because Ge can potentially replace Si in next-generation electronic devices. In this study, the coverage dependent adsorption behavior of tetrahydrothiophene on a Ge(100) surface was examined using high-resolution photoemission spectroscopy (HRPES), low energy electron diffraction (LEED), and density functional theory (DFT) calculations. The HRPES and DFT data indicated the evolution of two distinct adsorption geometries: a major interdimer row Ge− (CH 2 ) 4 −S−Ge structure via the ring-opening reaction and a minor molecularly adsorbed structure resulting from S dative bonding. Remarkably, the relative ratio of the interdimer row Ge−(CH 2 ) 4 −S−Ge configuration was gradually promoted as the surface coverage of tetrahydrothiophene increased, as confirmed by the HRPES results. Thus, we verified that the Ge(100) surface was dominantly covered by the interdimer row Ge−(CH 2 ) 4 −S−Ge adduct upon reaction with tetrahydrothiophene at a high surface coverage.