Abstract:

We report a more detailed understanding of the thermal-quenching and sensitization processes in tetrahedrally bonded amorphous semiconductors. In particular we reveal in detail the effect of light soaking, in hydrogenated amorphous silicon (a-Si:H), on the shift of the recombination transition, from the dangling bonds to the valence band-tail states as the temperature is lowered. Our experimental observations and model simulations are shown to account for various results in the literature, explaining in detail how the charge neutrality condition determines the recombination process in a-Si:H. This, in turn, demonstrates for the first time that it is possible to deduce the three valence states of the dangling bonds only on the basis of the recombination processes implied by the phototransport observations.