Photoelectron spectroscopy study of Ag/Si(111)√3×√3 and the effect of additional Ag adatoms

High-resolution core-level spectroscopy has been applied to the Ag/Si(111)√3×√3 surface. The Si 2p line shape is found to depend critically on the presence of additional Ag adatoms on the surface. A significant broadening caused by the surplus of Ag atoms could be eliminated by careful annealing. The resulting Si 2p spectra are significantly sharper than any published data for this or other Si based surface systems. Two major surface components are identified for the √3×√3 surface, which find a natural explanation in terms of the honeycomb-chained-trimer model. A small but characteristic contribution to the Si 2p spectrum of the Ag/√3×√3 surface is tentatively assigned to defects