A structural interpretation of Si-O-Si vibrational absorption of high-photoconductive amorphous a-SiOx:H films

The Si-O-Si stretching vibrational absorption in high-photoconductive amorphous silicon-oxygen alloy films prepared by rf glow discharge decomposition of SiH4-CO2 gas mixtures is investigated as a function of oxygen concentration. With increasing oxygen content, the peak position of the Si-O-Si bond stretching mode increases from 980 cm(-1) to 1080 cm(-1) The change of the absorption spectra with oxygen concentration is well analyzed on the basis of a two-phase structure model, in which each Si-rich phase (mostly a-Si:H) is surrounded by transition oxide SiO to SiO2 phase.