It was found that a novel kinetic equation, which was similar to the logistical function in biological systems, replicated well experimentally observed light-induced defect creation in such semiconductors. It was proposed that a defect, once created, itself had a triggering effect for successive defect creations. It was concluded that light-induced metastable defect creation initiated around pre-existing thermally equilibrated defects. A created defect then induced weak bonding which facilitated further defect creation. The self-limiting process for such defect creation was the recombination of 2 dangling bonds. The number of induced defects therefore saturated at a certain value; depending upon the illumination conditions. The recombination of 2 dangling bonds occurred on the way to stabilizing the dangling-bond states; thus resulting in bond-switching (defect diffusion). The annihilation of light-induced metastable defects by thermal annealing also occurred via the recombination of 2 dangling bonds during bond-switching at high temperatures, and under dark conditions. It was suggested that the defect creation could be suppressed in materials having a less flexible structural network.

Kinetics of Photoinduced Defect Creation in Amorphous Semiconductors - Analogy to a Logistic Equation in a Biological System M.Senda, N.Yoshida, K.Shimakawa: Philosophical Magazine Letters, 1999, 79[6], 375-81