Determination of hydrogenated amorphous silicon electronic transport parameters and density of states using several photoconductivity techniques

Abstract

In this paper, we show that the combination of different characterization techniques based on the photoconductivity of hydrogenated amorphous silicon can be a tool to investigate on the density of states and transport parameters of this material. We insist mainly on two techniques in which one records a photocurrent resulting from the movement of an interference grating onto a sample. We describe the experimental set-ups and provide a theoretical explanation of the observed behaviors of these photocurrents. We demonstrate that a density of state spectroscopy can be done with these techniques. Additionally, comparing this spectroscopy to that performed with modulated photocurrent experiment, we show that it is possible to derive a good order of magnitude estimate of the electron capture coefficient of the conduction band tail states as well as the electronic extended states mobility. The derived parameters are compared with previous results.