We have found thatB(the square of the gradient of (&agr;h&slash;&ohgr;)1/2versus h&slash;&ohgr; plot) is dependent on the preparation conditions ofa‐Si:H films and has a distinct correlation with photoconductivity.Bincludes information on the tail states and the band edge of extended states ofa‐Si:H.Bis proposed as one of important characterization parameters fora‐Si:H as well as photoconductivity.