High oxidation state at the epitaxial interface of γ-Al2O3 thin films grown on Si(111) and Si(001)

Abstract

High resolution synchrotron radiation x-ray photoelectron spectroscopy allowed us to identify the chemical bonding at the interface between epitaxial γ-Al2O3 and Si substrate. The experiments were performed on 1 nm thick epitaxial γ-Al2O3 layers grown on both Si(111) and Si(001) substrates. In both cases, the Si 2p core level decomposition recorded at photon energy of 160 eV provided evidence for the absence of Si2+ and Si3+ species and the presence of two different Si4+ species. A microscopic model is proposed for the interface obtained with two incomplete SiO2 planes based on the Si 2p3/2 line shape.