Oxide and interface properties of anodic films on Hg1−xCdxTe

Abstract

The oxide and interface properties of a 1200 Å anodic film on Hg0.8Cd0.2Te were studied by means of x-ray photoelectron spectroscopy (XPS) and capacitance voltage (C–V)a measurements on a metal–insulator–semiconductor (MIS) capacitance. The XPS results showed that the elemental composition of the anodic oxide is 59% O, 24% Te, 14% Cd, and 3% Hg. With the support of other experimental evidence, the anodic oxide was assigned a heterogeneous oxide of 58% CdTeO3, 19% TeO2, and 13% HgTeO3. A depth profile of the interface region, performed with the aid of Ar+ sputtering, revealed a significant depletion of Hg in the semiconductor side. These results are inconsistent with the recent model of the same oxide/semiconductor system, proposed by Nemirovksy and Finkman. The C–V curves from MIS measurements exhibited a large hysteresis indicative of a high concentration of positive–charge traps in the oxide, and characteristics indicative of a high density of surface states in the semiconductor surface region. A tentative model of the oxide and interface properties of this system was derived by combining the results of these two analyses. In addition, effects of the electron beam and of ion sputtering on this material are discussed.