Numerical calculation of the temperature dependences of photoconductivity in the p-type a-Si : H

Temperature dependences of photoconductivity in p-type a-Si:H were calculat ed numerically. The calculations were performed in terms of a simple recomb ination model in which the tunneling recombination of electrons captured by the states in the conduction-band tail and holes trapped at the states of the valence-band tail is accounted for at low temperatures. The results of calculations are consistent with experimental data, according to which the photoconductivity of p-type a-Si:H depends only slightly on the Fermi level position and on the total concentration of dangling bonds. The computer-as sisted numerical simulation suggests that the possible cause of this weak d ependence may consist in the differing extent of the valence- and conductio n-band tails. It is shown that the statistics of occupancy of the states in the mobility gap in a-Si:H under illumination differs vastly from that in the state of equilibrium. (C) 2001 MAIK "Nauka/Interperiodica".