A theory of the admittance of an amorphous silicon Schottky barrier

Abstract

In a recent paper Abram and Doherty (1982) described a calculation of the frequency-dependent differential capacitance of an amorphous silicon Schottky barrier. In this paper we adopt the same model of the Schottky barrier but employ a rather different method of analysis to calculate both the capacitance and the conductance. These are given as explicit formulae in terms of the angular frequency, the d.c. bias and the density of electronic states of the amorphous silicon. The expression for the capacitance is identical to that obtained by Abram and Doherty. Numerical results for the admittance as a function of frequency and bias are presented for a density of states consisting of a single peak in a constant background, and for two forms of the density of states that have recently been proposed for amorphous silicon. The results suggest that the frequency dependence of the conductance is the most sensitive indicator of features in the density of states of amorphous silicon.