Dynamic investigations of (0001) Al2O3 surfaces treated with a nitrogen plasma

Abstract

We investigated the kinetics of AlN and AlNO phase formation on a sapphire substrate at different nitridation temperatures in an ultra-high vacuum. Dynamic reflection high-energy diffraction observations revealed that the growth rate of AlN decreased abruptly as the nitridation temperature increased, due mainly to the low sticking coefficient of nitrogen atoms. In addition, the formation of AlNO was enhanced by the oxidation of AlN at a high substrate temperature, which we discuss in terms of the protrusion density based on atomic force microscopy results. X-ray photoelectron spectroscopy spectra support our conclusions and indicate the importance of the metallic Al composition on the sapphire surface during the nitridation process.