Atomic structure of SiO at SiO rSi interfaces

The valence-band and O 2s core-level spectra of ultrathin about 1 nm.SiO2 layers formed in the initial stages of the oxidation of Si 100.substrates were measured by high-resolution X-ray photoelectron spectroscopy XPS., and the energy difference between the bonding states in the valence-band and the core-level was found to be larger than the corresponding difference for the bulk SiO2. The energy difference between the top of the valence-band and the core-level was also found to be larger than that for the bulk SiO2. From the first-principle molecular orbital MO.calculations for SiO2 model clusters, Si5O16H12., it was concluded that the atomic structure of SiO2 at the SiO2rSi interfaces is characterized by a narrow intertetrahedral bond angle, about 1358. q2000 Elsevier Science B.V. All rights reserved.