The problem of low drift mobility of holes in hydrogenated amorphous silicon (a-Si:H) has been solved by controlling the hydrogen content in the film. A-Si:H films with low hydrogen content have been prepared by the radical-controlled method in which the glow discharge of the mixture of SiF4 and H2 is used and the residence time of the reactant species is controlled. A prototype MOSFET demonstrates a hole mobility of 0.12 cm2/Vs and an electron mobility of 0.24 cm2/Vs, suggesting the feasibility of the a-Si CMOS circuit.