This article presents a theory for nonequilibrium carrier kinetics in amorphous semiconductors containing localized states among which finite interactions are allowed via tunneling. Fourier domain solutions are explored intensively in order to quantitatively interpret the frequency-dependent photocarrier drift mobility determined by modulated photoconductivity measurement. The theoretical analysis is in agreement with experiments carried out for hydrogenated amorphous silicon over a wide range of frequencies and temperatures, and discloses that the inclusion of tunneling transitions considerably accelerates carrier thermalization in localized band-tail states. A generalized recombination model that considers both direct capture of band carriers and tunneling transfer of band-tail carriers into recombination centers is also discussed in detail, suggesting that even for room temperature, the tunneling recombination takes place preferentially.

• Received 8 December 2000

DOI:https://doi.org/10.1103/PhysRevB.64.125208