Correlations between the chemical and electronic structure of thermally treated anodized InSb

Abstract

We investigated the effects of heat treatments on the interfacial chemical and electronic properties of InSb metal–oxide–semiconductor structures prepared by plasma and wet anodization. Using line–shape depth profiling by Auger electron spectroscopy, we note that annealing at increasingly elevated temperatures monotonically enhances the extent of O indiffusion, increases the width of the In–In oxide and Sb–Sb oxide interfaces, and changes their overlap and relative positions. The effect of the heat treatments on the capacitance–voltage (C–V) characteristics was noted by a marked decrease in the oxide trap and fast interface state densities for both oxidation methods. However, the fixed oxide charge density increased for wet anodic oxides and decreased for plasma-grown samples. The asymmetric effect of the bias voltage on the C–V curves was also analyzed. We present a model which correlates the electrically active species with different spatial positions and oxidation states of In and Sb at the oxide layers and at their interfaces. The model successfully explains the experimental observations.