Light-induced degradation of "a-Si:H" - a comparison of short-laser-pulse and steady light degradation

An undoped and a compensated a-Si:H sample have been degraded by 17-34 ns laser pulses and by steady light (CW) at 78K and 300K. The light-induced defect concentration N is monitored by the increase in subgap absorption α. For the same change in a α pulses degrade the photoconductivity σ_p more than CW light and more strongly for exposures at 78K than at 300K. The lack of correlation between σ_p and N suggests that light soaking causes additional damage besides an increase in N. This additional effect is more pronounced for pulse and low temperature exposures.