Optical Bias Control of Dispersive Relaxations in a -Si: H

Relaxation of the photoinduced ir absorption band in a-Si: H was studied in the microsecond time domain as a function of cw bias illumination. The decays follow a power law t^-α where the dispersion parameter α increases with bias illumination. At low temperatures, α increases linearly with the steady-state carrier density while at high temperatures it saturates at high illumination levels. These results are interpreted as evidence for the bias-controlled tunneling process at low temperatures and multiple trapping process with tail states under the saturation condition at high temperatures.