It was found that, in plasma-deposited films of amorphous hydrogenated material, the time dependence and saturation value of the metastable defect density that was produced by high-intensity illumination depended upon the material properties. By using a wide range of deposition techniques, it was shown that there was a marked correlation between the steady-state defect density and the monohydride Si-H bond concentrations which were detected by infra-red transmission. The [SiH]2000 values ranged from 2 to 16%. A microscopic description was proposed for light-induced defect creation and light-induced defect annealing in amorphous hydrogenated material. It was based upon the trapping of mobile H at 2 specific sites. These were the Si-H bond and the Si dangling bond. The model predicted the existence of a steady-state defect density that was proportional to the monohydride [SiH]. In the case of production of mobile H in 3-center (Si-H-Si) configurations, a low-energy mechanism with no need for Si-H bond breaking was suggested by the observed changes in the infra-red absorption of the various H-bonding configurations during light-soaking. Together with the assistance of electron hole-pair recombination, it consisted of the excitation of 2 adjacent H atoms from a (Si-H H-Si) configuration plus Si-Si bond reconstruction.

C.Godet, P.Roca i Cabarrocas: Journal of Applied Physics, 1996, 80[1], 97-102