SiC/SiO 2 interface states observed by x-ray photoelectron spectroscopy measurements under bias

Abstract

Energy distribution of interface states at an ultrathin SiO2/SiC interface is obtained by means of x-ray photoelectron spectroscopy (XPS) under bias. The substrate Si 2p peak shows a reversible energy shift by the application of a bias voltage to SiC with respect to the Pt layer of the 〈Pt/SiO2/6H–SiC(0001)〉 structure, and the analysis of the shift clarifies that an interface state peak is present near the midgap. The analysis of the current–voltage curves shows that in the entire bias region, the interface states communicate with conduction and/or valence bands under x-ray irradiation, and consequently, despite the wide-gap semiconductor, interface states in the whole band-gap region are observable by this method.