Band-bending inhomogeneity of Au adsorbed surface evaluated with Si 2p core-level spectra

Si 2p core-level spectra (CLS) of Au adsorbed Si ( 111 ) - 3 × 3 -Ag surface at various Au coverages were measured using photoemission spectroscopy. At very low Au coverage where identical Au nanoclusters randomly distribute on the surface, the Si 2p CLS are reasonably decomposed, which implies the dispersed electrostatic potentials induced by the Au nanoclusters are strongly screened so that the inhomogeneity of the underlying band-bending is negligible. However, at a higher Au coverage where a part of Au nanoclusters aggregate into the Si ( 111 ) - 21 × 21 - ( Ag + Au ) superstructure ( 21 -Au ), the Si 2p CLS cannot be fully decomposed but be reproduced by combination of the CLS obtained from a pure Au nanocluster phase and a 21 -Au phase. This indicates a strong band-bending inhomogeneity due to the partially aggregation of Au nanoclusters on the surface.