Low-temperature electron transport near the mobility edge of amorphous silicon

At temperatures below 80 K, well beyond the multi-trapping regime, we have observed a remarkable rise in the electron drift mobility μe to values of 5 cm2 V−1 s−1 or more. μe depends systematically on the intensity of an excitation pulse preceding the laser-generated transit signal. It is concluded that the observed transport is associated with electron hopping in the rapidly increasing tail-state distribution, the hopping path depending on the level to which these states are filled. The interpretation is supported by a preliminary analysis of the results.