We have studied the effects of ion implanting boron into glow discharge deposited hydrogenated amorphous silicon films (a‐Si:H). Electrical activity more than two orders of magnitude higher than previously reported1is measured in our samples. Implantations of Si ions are used to study the effect of post‐annealing on the radiation damage. Hydrogen introduced by low‐energy implantation and diffusion is found to completely recover electrical and optical characteristics in Si‐implanted specimens even at the highest concentrations (1021/cm3), where annealing for 1 h at 260 °C was insufficient. Introduction of H in B‐implanted samples was found to deactivate the boron, which can be reactivated by low‐temperature annealing.