Influence of a-SiNx: H composition on transfer-doping and electron-trapping effects in a-SiNx: H/a-Si: H superlattices

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Abstract
The influence of the composition of a-SiNx: H on transfer-doping and electron-trapping effects has been studied in a-SiNx: H/a-Si: H superlattices by measuring in-plane currents. It was found that transfer doping is caused by electron transfer from donor-like states in the a-SiNx: H layer to the a-Si: H layer, and the maximum doping effect occurs at the a-SiNx:H composition of x = 0·85. The origin of the transfer-doping effect is considered to be a structural change in the a-SiNx: H layer. Measurement of photocurrent decay reveals that electron trapping by the a-SiNx: H layer occurs in the superlattice and that it extends to the inner part of the 100 å-thick a-SiNx: H layer. It is also found that the decay time of the photocurrent depends on the a-SiNx: H composition and the temperature. The results suggest that the bottom of the deep-state distribution in the a-SiNx: H layer rises above the Fermi level with increasing x.