Statistical Cross-Linking at the Si(111)/SiO₂ interface

Angle-resolved photoemission measurements of the Si 2p core level as a function of polar emission angle were carried out to investigate the atomic populations and depth distributions of Si in various oxidation states for a SiO₂ film thermally grown on Si(111). The suboxide states including Si¹⁺, Si²⁺, and Si³⁺ exhibit different depth distributions. Despite these differences, the results are consistent with a chemically abrupt interface. A simple model based on the statistical cross-linking of dangling bonds between a bulk-truncated Si and an amorphous SiO₂ layer explains our observations.