Influence of potential fluctuations on photoconductivity in a-Si : H

The effects of long-range potential fluctuations (LRPF) on the d.c. and a.c. photoconductivities of undoped hydrogenated amorphous silicon (a-Si : H) have been discussed in the temperature region 20–300 K. It is found that the a.c. photoconductivity in the entire temperature range is dominated by dielectric relaxation, and not by any electronic hopping motion. A reasonable fit of the experimental data to a model calculation based on LRPF is obtained, and the extent of the potential fluctuations is deduced to be ～0.06 eV in energy and ～10 nm on a length scale.