Photoluminescence in hydrogenated amorphous silicon

By starting with exponential band tails of localized states, it is shown that the photoluminescence of $a$-Si: Hi can be explained with no further assumptions. The spectrum and its changes with temperature, with time, and with pump intensity and energy, and the decay curves and lifetime distributions, are predicted by the model, qualitatively, and, when the calculation is feasible, quantitatively.