Published online by Cambridge University Press: 25 February 2011
Optical bias enhancement in transient photocurrent, by a factor of more than 10, is observed in a-Si:H films. The transient photocurrent is found to decay exponentially shortly after the light pulse is turned off. The exponential decay constant of the transient current is found to be proportional to (optical bias level)−0.38 at room temperature. A theory based on the multiple trapping model is developed to explain the experimental result. This effect is applied to study the density of state of the sample as well as the process of charge recombination.