The thermal annealing of light‐induced defects inp‐i‐pandn‐i‐nhydrogenated amorphous silicon (a‐Si:H) structures has been studied at 140 °C under ohmic and single‐carrier injection conditions. The influence of hole or electron injection on steady state defect density and relaxation time of the isothermal defect annealing has been studied. All the experimental results can be qualitatively explained by a simple model in which the creation rate of the defects in intrinsica‐Si:H is proportional to then‐pproduct of the carrier densities, and the annealing rate is proportional to the product of defect density and hole density. ©1995 American Institute of Physics.