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Photocapacitance Studies Of Light Induced Changes in the Density of Gap States of N-Type Doped and Undoped Hydrogenated Amorphous Silicon Films
Published online by Cambridge University Press: 26 February 2011
Abstract
We have studied the photoinduced changes of the conduction bandtail states and dangling bond defects in a series of n-type doped hydrogenated amorphous silicon samples of different doping levels, using the techniques of drive level capacitance profiling and voltage pulse transient photocapacitance. Each film was examined in a series of partially annealed states of progressively higher anneal temperature following light soaking. A general decrease in the number of dangling bonds and an increase in the number of occupied bandtail states was observed with increasing anneal temperature. The observed changes are discussed with respect to previously proposed defect reactions for photoinduced changes in n-type doped films, and we conclude that none of them can explain the observed changes in the lower doped film. Second, we discuss the application of transient voltage pulse photocapacitance and transient junction photocurrent to the study of the energy distribution and trapping properties of the photoinduced dangling bond defects in undoped hydrogenated amorphous silicon. We observe that the hole capture cross section of the photoinduced deep defects is larger by a factor of 3.3 compared to that of the intrinsic deep defects.
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- Copyright © Materials Research Society 1988
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