Transient photocurrent decay in hydrogenated amorphous silicon
Palsule, Chintamani P.
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The objective of this work is to study the localized states at the conduction band edge and the drift mobility of the carriera in hydrogenated amorphous silicon(a-Si:H) using coplanar geometry samples. Transient photocurrent measurements have been used for this purpose. The transients have been recorded on undoped and phosphorus-doped a-Si:H thin film coplanar geometry resistors, using a strongly absorbed short pulse excitation from nitrogen pumped tunable dye laser with a pulse-width of 500 pa. The temperature dependence of these transients has been measured in a temperature range from 100 K to 400 K. We find that the dispersion parameter is very weakly temperature-dependent and mobility shows an activated behavior with temperature. So we feel that the multiple trapping theory cannot be applied if the band-tails are assumed to be exponential. We find electronic mobility values consistent with the existing literature.