Light-induced metastable defect creation was studied in amorphous samples which had been prepared by using He or H dilution during plasma-enhanced chemical vapor deposition. By comparing the light-induced degradation of the electronic properties and defect densities of He-diluted alloy films, with those of H-diluted amorphous hydrogenated material, it was found that not only the optical gap but also the microstructure of alloy films was responsible for light-induced degradation. Because He-diluted samples had a compact network and an improved microstructure, they were more stable than were H-diluted amorphous hydrogenated material with the same optical gap. The temperature dependence of the mobility-lifetime product in the annealed state and in the light-soaked state also showed that the creation of light-induced recombination centers in He-diluted amorphous hydrogenated material was lower than that in H-diluted material.

S.Hazra, A.R.Middya, S.Ray: Journal of Physics D, 1997, 30[3], 325-9