Hole carrier transport in amorphous silicon films

Abstract

The technique of Monte Carlo simulation is applied to trap-limited hole carrier transport in amorphous silicon thin films. The distribution in energy of localized states assumed for the model is that derived by Spear and co-workers for silicon films prepared by the glow discharge decomposition of silane.

Hole transit pulses are simulated for a suitable variety of conditions of applied electric field and specimen temperature. The current-time data obtained, which exhibit the ‘anomalous’ degree of dispersion characteristic of many disordered semiconductors, are compared with those observed experimentally.

The dispersive character of the carrier transport process is further reviewed in terms of the equilibration of the drifting charge sheet with the broad distribution of trapping centres present, and an evaluation is made of the extent to which dispersive transport pulses can be employed to obtain information on the distribution of localized states in amorphous semiconductors.