The effects of the nature of the H bonding and distribution on light-induced metastable defects were investigated in detail in a-Si:H films deposited by radio-frequency magnetron sputtering at high rates (about 1.5nm/s) with different H dilution in the gas phase mixture (Ar + x%H2) (x = 5 to 20%). A combination of optical transmission and photo-thermal deflection spectroscopy measurements, correlated with infrared absorption ones, was used to characterize the samples in their as-deposited, annealed and light-soaked states. The results indicate that the increase in the light-induced density of defects was strongly dependent on the amount of the relative proportion of the polyhydride (Si-H2 and [Si-H2]n) groups present in the as-deposited films, which favour the formation of structural inhomogeneities and increase the disorder. The results also showed that optimized films could be elaborated and exhibited better stability than optimized samples elaborated at much lower rates (about 0.1nm/s) by other techniques. The results were explained within the context of the potential fluctuation model.

Effect of the Nature of the Hydrogen Bonding on the Light-Induced Metastable Defects in Hydrogenated Amorphous Silicon Prepared by Radiofrequency Magnetron Sputtering. M.Daouahi, A.Ben Othman, K.Zellama, L.Chahed, M.Essamet, H.Bouchriha: Physica Status Solidi B, 2002, 231[2], 373-84