Determination of the source of two extra components in Si 2p photoelectron spectra of the SiO 2/Si(1 0 0 ) interface

Abstract

Ultrathin silicon oxide films were thermally grown on Si(1 0 0 ). High resolution photoelectron spectra of the Si 2p core-level were recorded at a photon energy of 180 eV. Applying a fitting procedure to these spectra allows to separate various components. The line-shape consists of seven resolved components, which correspond to the electron signals of unoxidized Si 0 and the various different oxidation states of silicon (Si 1+, Si 2+, Si 3+, Si 4+). The Si 0-signal was composed of the bulk signal (B) and two extra components (Si α, Si β). In order to determine the origin of these extra components a photoelectron diffraction analysis was performed. A model for the atomic structure at the interface is proposed. Within this model the Si α and Si β signal are assigned to specific atom positions.