PHOTOCONDUCITIVITY OF INTRINSIC AND DOPED a-Si:H FROM 0. 1 TO 1. 9 ev.

Abstract

The photoconductivity of intrinsic and doped a-Si:H was investigated from 0. 1 to 1. 9 ev by the use of a fourier-transform infrared spectrometer with a-Si:H as the detector. The photoconductivity spectra of intrinsic a-Si:H consist of two broad peaks. One, at 1. 8 ev, is the band-to-band transition and the other is the subband at 0. 9 ev. The peak position of the subband does not show a temperature dependence. Doping with PH//3 increases the intensity of the subband photoconductivity and shifts the peak to 1. 2 ev, which is the only peak observed in the photoconductivity spectra for highly doped a-Si:H. For B//2H//6 doping, the subband spectrum becomes broader and merges into the tail part of the band-to-band transitions with a bump at 1. 3 ev. From these results the impurity levels in a-Si:H are discussed.