Decay of photocurrent from the steady state ina-Si:H films

Results are reported on the long-time decay of the photocurrent from the steady state in undoped a-Si:H films. The decay has been studied for various illumination intensities and over a wide temperature range, from 300 down to 50 K. It is found that the long-time photocurrent decay is a strong function of the steady-state illumination intensity when the intensity is low. As the light intensity is increased, the decay gradually approaches a power-law behavior Iₚₕ{~}t^-β and eventually becomes intensity independent. {β} is found to vary nonmonotonically with temperature; a peak appears between {~}110 and {~}150 K, depending on the history of the sample as well as on the sample itself. Some possible photocurrent decay models are examined.