Valence-band offset variation induced by the interface dipole at the SiO2/Si(111) interface -: art. no. 155325

X-ray photoelectron spectroscopic evaluation of the SiO2/Si(111) interface reveals that the valence-band offset differs by about 0.19 eV between two types of atomic structures that contain Si atoms in different intermediate-oxidation states. The difference in the valence-band offset is reproduced by a first-principles molecular orbital calculation for model clusters (Si17O4H36 and Si17O3H36) of the two interface structures. It is concluded that the valence-band offset at the interface with more Si atoms in the 3+ oxidation state than in the 1+ oxidation state is larger than the valence-band offset at the interface with more Si atoms in the 1+ oxidation state. This is thought to be a result of the depolarization effect making the interface dipole smaller at the interface with more Si atoms in the 3+ oxidation state.