Electronic transport and recombination in amorphous semiconductors at low temperatures

The problem of simultaneous diffusion and recombination of electron-hole pairs, photoexcited in noncrystalline semiconductors at low temperatures, is reduced to a universal mathematical problem whose solution does not depend on the density-of-states function. We derive a general geminate-recombination function which at low light intensities describes the distribution of radiative recombination times. The low-temperature photoconductivity is found to depend only weakly on material parameters and agrees with experiments on hydrogenated amorphous silicon.