Surface charge spectroscopy—A novel surface science technique for measuring surface state distributions on semiconductors

Abstract

A novel technique, surface charge spectroscopy (SCS), has been developed for measuring interface state density at a dielectric-semiconductor interface in conjunction with x-ray photoelectron spectroscopy (XPS). In this technique, a thin dielectric layer with thickness up to 15 nm, is deposited on a semiconductor substrate. The surface Fermi level (EFs) of the semiconductor and the surface potential of the dielectric are measured using XPS, the latter of which can be varied by charging the dielectric with electrons from a low energy electron flood gun commonly equipped inside an XPS system. The interface state distribution in the band gap of the sample is then extracted from the relationship between the EFs and the dielectric surface potential with a simple space-charage calculation similar to the conventional capacitance-voltage technique. Experimental data on SiO2/Si and SiNx/InP samples are shown in the article to illustrate the applicability of SCS.