LIGHT-INDUCED-CHANGES IN THE PHOTOCONDUCTIVITY OF RAPIDLY-DEPOSITED HYDROGENATED AMORPHOUS-SILICON FILMS

The temperature dependence of steady-state photoconductivity in hydrogenated amorphous silicon films prepared at high deposition rates have been measured in thermally-annealed states (state A) and light-soaked states (state B). The light-induced changes (the Staeble-Wronski effect) in the photoconductivity were studied using a computer simulation calculation process. The Simmons-Taylor theory and occupation statistics of correlated defects were used to describe the exponential distribution band tail states and the dangling bond states. Tunneling recombination of excess carriers was taken into account at low temperature. It was found that the density of dangling bond states increases after light soaking, but there is no change in the density and distribution of band tail states. A discussion of the experimental and simulation results is given.