Effect of the nature of the hydrogen bonding on the light-induced metastable defects in hydrogenated amorphous silicon prepared by radiofrequency magnetron sputtering

The effects of the nature of the hydrogen bonding and distribution on light-induced metastable defects are investigated in detail in a-Si:H films deposited by radiofrequency magnetron sputtering at high rates (similar to15 Angstrom/s) with different hydrogen dilution in the gas phase mixture (Ar + x% H-2) (x = 5-20%). A combination of optical transmission and photothermal deflection spectroscopy measurements, correlated with infrared absorption ones, is used to characterise the samples in their as-deposited, annealed and light-soaked states. The results indicate that the increase in the light-induced density of defects is strongly dependent on the amount of the relative proportion of the polyhydride (Si-H-2 and (Si-H-2)(n)) groups present in the as-deposited films. which favour the formation of structural inhomogeneities and increase the disorder. The results also show that optimised films can be elaborated and exhibit better stability than optimised samples elaborated at much lower rates (similar to1 Angstrom/s) by other techniques. The results are discussed as a whole in the context of the potential fluctuation model.