Numerical study of thermal generation current in a-Si : H based schottky barrier

By using detailed computer simulations, we explore the origin of the dark current and its dependence on the reverse bias of intimate hydrogenated amorphous silicon (a-Si : H) Schottky-barrier structures used as solar cells. The results show that when the recombination rate becomes negative, the dark current is due to the thermally generated carriers. On the other hand, we show that the thermal generation of carriers is dominated by the emission from a narrow band localized near to the midgap and consequently, the dark current is proportional to the DOS of this band. The slow dependence of the dark current with reverse bias is due to the dependence of the fraction of sample depleted.