Atomic and Electronic Structure of Au/Si(111)-(root 3 x root 3-)R30 degrees: Density-Functional Theory Calculations

Abstract

The atomic and electronic structure of the Au/Si(III)-(root 3 x root 3)R30 degrees surface has been studied by density-functional theory calculations. We examined the potential energy surface for various Au adsorption configurations with 1 monolayer coverage and identified two local-energy minimum structures, which correspond to the twisted trimer (TT) model and the conjugate honeycomb-chained-trimer (CHCT) model. The honeycomb-chained-trimer (HCT) model, reported as a stable structure in a previous study, turned out to be locally unstable. The TT model is slightly more stable by 0.01 eV than the CHCT model, and there is an energy barrier of 0.05 eV between the two models. While the TT and CHCT models produce similar scanning-tunneling-microscopy simulation images, comparing well with experiments, their surface band structures are distinct in energy and dispersion, but both of them are in partial disagreement with angle-resolved photoelectron spectroscopy measurements.