Study of Si 2p core level shift at the As/Si(0 0 1)-2×1 surface

The atomic origin of the photoemission Si 2p core level, shifted at 0.35 eV higher binding energy, at the As/Si(0 0 1)-2×1 surface, is investigated. The study is based on the determination of the surface structure by means of multiple scattering analysis of As 3d azimuth photoelectron diffraction (PD) patterns. The obtained structure is used to assign the atomic origin of the Si 2p component by surface core level shift PD. We find that a single atom contributes to the core level, while, on the basis of final state calculations, a contribution from two different atoms would be expected.