By using the photomixing technique we have found that the drift mobility (&mgr;d) of intrinsic hydrogenated amorphous silicon (a‐Si:H) films produced by both glow discharge and hot wire techniques increases with increasing electric field, while the lifetime (&tgr;) decreases with increasing electric field, and the &mgr;d&tgr; product is essentially independent of the electric field. We have also found an empirical relationship that a greater field dependence of the drift mobility of ana‐Si:H film in the annealed state indicates a poorer stability of the photoconductivity upon light soaking. ©1996 American Institute of Physics.