High resolution XPS study of oxide layers grown on Ge substrates

High resolution X-ray photoelectron spectroscopy (XPS) was used to analyze thin layers of germanium oxide grown on germanium substrates under various conditions. The results reveal the presence of high density of electron states located at the oxide/germanium interface that lead to the energy band bending. The surface of native oxide layers and that of thin oxide layer grown under dry oxygen correspond to GeO2 composition. Under Ar etching, lower oxidation states were revealed. Short in situ heat treatment at T=673 K under ultrahigh vacuum leads to the removal of the oxide layer. In addition, the analysis of the layer grown at T=653 K under dry oxygen suggests that carbides form at the oxide/substrate interface.