Hopping‐randomwalk of electrons at localized band tail states in random fractal fluctuation

Power law decays in dispersive transient current and photoluminescence in amorphous semiconductors are explained from hopping-randomwalk of carriers at localized band tail states in random self-affine fluctuation of the 3.9 fractal dimension. The hopping-randomwalk is reported. The mean square distance is given by 〈r(t)2〉 ∼ tκ with κ < 1, which shows anomalous diffusion. The hopping area where electrons pass through is complicated and has a fractal dimension. The fractal and fracton dimensions of the randomwalk are calculated at different temperatures. The fractal and fracton dimensions of the hopping-randomwalk in amorphous semiconductors is shown to be able to be obtained from the dispersive transient current and photoluminescence decay. It is shown that the temperature behavior of both dimensions in a-Si:H agrees with that in the simulation of the hopping-randomwalk. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)