Photoconductivity and photoinduced absorption in a‐Si:F and a‐Si:H

The photoconductivity (PC) and photoinduced absorption (PA) of RF glow discharge a‐Si:F and a‐Si:H samples is reported. The value of the room temperature PC of a‐Si:F is lower by some four orders of magnitude relative to that of a‐Si:H, but the PA of a‐Si:F is found to be significantly higher than that of a‐Si:H. This indicates that the recombination rate of the excess carriers is lower in a‐Si:F than it is in a‐Si:H, yet a larger fraction of the excess carriers are trapped in the band tails of a‐Si:F, leading to its low PC. From the analysis of our PA data, we also determine the position of the mobility edge with respect to the extrapolated band edge in a‐Si:H.