The kinetics of light-induced defect creation in a-Si:H was studied in early-time limit and as function of pre-existing defects of different thermal stability by electron spin resonance and optical spectroscopy techniques. Both for cw and for laser pulse exposures, the early-time kinetics follows sub-linear tβ time dependences, similar to the long-time limit. In addition, the overall defect creation rate was not a single function of the total defect number. Instead, it depends on the thermal stability, or annealing energy distribution, of the defects present in the film. Furthermore, creation of the thermally less stable defects was unaffected by the presence of a large number of stable defects introduced by pre-exposure at a higher temperature. These findings questioned the existing defect creation models.The thermal stability of the light-induced defects depended upon the network microstructure, the less stable defects being created in a-Si:H deposited near to the microcrystalline transition.

Thermal Stability of Light-Induced Defects in Hydrogenated Amorphous Silicon - Effect on Defect Creation Kinetics and Role of Network Microstructure. P.Stradins, M.Kondo, A.Matsuda: Journal of Non-Crystalline Solids, 2008, 354[19-25], 2144-8