Photoconductivity and Density of States in “Microstructural” Amorphous Silicon

Abstract

ABSTRACTIt has been reported in previous works that using of RF 55 kHz PECVD method allows to deposit microstructural inhomogeneous a-Si:H films at high deposition rate (10–20Å/c) and with high photoconductivity The structural analysis with using of IR spectroscopy and atomic force microscopy (AFM) performed in this work have shown that these films possess a relatively regular microstructure consisting of “grains” with characteristic size of∼300–500Å. The regular microstructure of investigated films differs them from inhomogeneous a-Si:H with deteriorate electronic properties. At the same time the diffraction analysis didn't reveal the presence of microcrystals. Therefore, we denoted our films as “microstructural” a-Si:H films In this work we performed the modeling of the photoconductivity of “microstructural” a-Si:H films to analyze the density-of-states (DOS) responsible for recombination kinetics For this purpose different approaches to photoconductivity modeling have been used to simulate the experimentally measured temperature dependence of photoconductivity The comparative analysis of results of these simulations and ESR measurements have shown that recombination in high photoconductive ‘microstructural’ films is controlled by deep neutral states