Photoconductivity and electronic doping effects in hydrogenated amorphous silicon

The concept of electronic doping is used to explain unexpectedly large values of the diode quality factor (exceeding two) and supralinearity which is sometimes observed in amorphous silicon p-i-n-type diodes and materials, respectively. This suggests the presence of an extra set of defect states in lightly boron-doped films with a capture rate for electrons which is much larger than that of the inherent defect states. We also report that for high-quality undoped intrinsic layers, the photoconductivity versus intensity behavior exhibits sublinear power dependence which increases with intensity in distinct contrast to the previously reported results. We provide a self-consistent model which is able to explain the above observations.