The role of dangling bonds in the electronic and vibrational properties of hydrogenated amorphous silicon nitrides (a-Si1-xNx : H)

Hydrogenated amorphous silicon nitrides have been obtained as thin films deposited by plasma-enhanced chemical vapour deposition onto (100) silicon wafers. Two different samples have been obtained with similar deposition conditions in the plasma chamber but varying the SiH4/NH3 molar ratio. We used various spectroscopic techniques to ascertain how the different sample composition influences the remarkable spectroscopic differences observed. The contribution of the Si dangling bonds, randomly dispersed in the bulk of the amorphous material but with noticeable segregation on the surface, has been considered as the main source of recombination processes producing emission states. Thermal annealing strongly influences the photoluminescence emission spectra because diffusion processes induce lowering of dangling-bond concentration. Copyright (C) 2007 John Wiley & Sons, Ltd.