The recombination lifetime in phosphorus-doped hydrogenated amorphous silicon is determined from the dispersive photocurrent decay following a short-pulse excitation. The electron drift mobility and dispersion parameter α are obtained as well. It is found that α is temperature dependent as expected for extended-state transport controlled by multiple trapping. A lower limit to the extended-state mobility is determined: μc>~1 cm2/V.s. © 1980 The American Physical Society.