Determination of the source of two extra components in Si 2p photoelectron spectra of the SiO2/Si(100) interface

Ultrathin silicon oxide films were thermally grown on Si(I 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 (Si1+, Si2+, Si1+, Si4+). The Si-0-signal was composed of the bulk signal (B) and two extra components (Si-alpha, Si-beta). 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-alpha and Si-beta signal are assigned to specific atom positions. (c) 2005 Elsevier B.V. All rights reserved.