An Analysis of Infrared Stimulated Current in a-Si:H Based on a Model of Three-step Excitations

An analysis of the infrared stimulated current in a-Si:H is presented based on a model of three-step excited processes. Since the photon energy of the infrared (i.r.) stimulated beam is less than half of the band gap, generation of the photon current under the infrared illumination is originated from the mechanism of a three-step excited process. To match with the experimental result, we find that the excitation rate b' from the lower localized states to the higher localized states In the band gap is much smaller than that from the valence band to localized states and from localized states to the conduction band. The steady state value of the density of the free carriers only depends on b', average recombination time τ and density of localized states g(E).