The Simulation of a-Si:H Junction Capacitance Measurements

Abstract

Junction capacitance measurements have been used by many researchers to study the density of states in the mobility gap of hydrogenated amorphous silicon. However, the data analysis methods used for these studies are based on approximate analytic models which may not always be appropriate. In order to understand better the experimental method and the models, we have performed simulations using a numerical simulator which can calculate the complete time-dependent response of an amorphous semiconductor device. The current in a device is simulated as a function of time when a small sinusoidal voltage applied in addition to a DC bias voltage. The out-of-phase and in-phase components of the sinusoidal part of the current are used to calculate the capacitance and series resistance, just as they measured in an experiment. The results of simulated experiments at different temperatures are shown.