Density of gap states in amorphous semiconductors by the field effect

Abstract

Amorphous semiconductors contain broad distributions of localised states in their mobility gaps. The paper presents an analysis of how the density of these states may be deduced from the field effect. In response to the application of a transversal fieldF x a space charge distribution results. The gross features of the corresponding distorted band structure are reflected in the longitudinal conductanceG z. The main task is to convert this implicit information into explicit formulae which enable the direct estimate of the density of the localised states from the measuredG z versusF x functions. This is accomplished by studying a somewhat simplified model which approximates the density of states by piecewise constant parts.