Lifetime-resolved studies of photoluminescence (PL) after the light-induced creation of defects by illumination of pulsed light have been done for a-Si:H based films including a band-edge modulated (BM) a-Si 1 m; x N x :H film in which the PL is dominated by emission from excitons. The decrease in intensity of PL after the illumination of the BM film was more significant than that of a-Si:H. The role of excitons in the creation of light-induced defects is discussed.