Monte Carlo Simulation of Transient Currents in a-Si:H

Abstract

AbstractMulti-trapping transient currents through pure exponential band tails are calculated by Monte Carlo simulations of unprecedented accuracy. The time and energy dependent carrier distributions, the current and the charge signals are obtained. The transit time tT and the dispersion parameters α1, and α2, before and after the transit time, are extracted from the simulated currents. Results are presented for the expected temperature dependence of α1 and α2 and of the drift mobility μD for electrons and holes in a-Si:H. At low temperature, α1 = α2 = T/To is found, but above T ≈ 0.6To, α1, bends downwards to saturate at 1 at high temperature while α2 bends upwards, clearly improving the agreement with the experimental data. The temperature dependence of the drift mobility μD is well reproduced for holes with a microscopic mobility of μo = 0.5 cm2V−1s−1. For electrons, the agreement is also excellent but the surprisingly low value of μo = 4 cm2V−1s−1 is found.