Abstract
It is proposed that in a-Si: H illumination can induce metastable dangling-bond defects via a two-step mechanism. In the first step, weak Si -Si bonds are broken by trapping of photo-generated holes into localized valence-band tail states and then, in the second step, the broken bonds are stabilized by a bond-switching mechanism. Assuming that the energy required for bond switching is provided by non-radiative, bimolecular recombination events, it is shown that the experimentally determined kinetics of defect formation can be derived from the known tail-state parameters of a-Si : H.