It was observed that pulsed sub-bandgap illumination created dangling bonds with a density of about 1018/cm3 in high-quality hydrogenated amorphous Si films. Such a light-induced creation of dangling bonds could be accounted for in terms of a model in which self-trapping of holes in weak Si-Si bonds adjacent to a Si-H bond plays an important role. The kinetics of thermal annealing of the light-induced dangling bonds were examined, in which half of the defects were annealed out above 180C, but half of them remained.

Light-Induced Defect Creation under Pulsed Sub-Bandgap Illumination in Hydrogenated Amorphous Silicon. K.Morigaki, H.Hikita, H.Takemura, T.Yoshimura, C.Ogihara: Philosophical Magazine Letters, 2003, 83[5], 341-9