Silicon–carbon–oxynitrides grown by plasma-enhanced chemical vapor deposition technique

In this paper we report some preliminary results about the growth at low temperature (493 K) of hydrogenated silicon–carbon–oxygen–nitrogen amorphous thin-film alloys (a-SiCxOyNz:H) by means of capacitively-coupled radio-frequency (13.56 MHz) plasma-enhanced chemical vapor deposition using a mixtures of silane (SiH4), propane (C3H8), nitrous oxide (N2O) and ammonia (NH3) precursor gases. Thin films of a-SiCxOyNz:H were grown at different deposition conditions, obtaining growth speeds varying from 0.22 to 0.44 nm/s. The films were characterized by means of Fourier transform infra-red spectroscopy in order to investigate the internal bonding structure, by UV–VIS transmittance spectroscopy to check the optical properties and by mechanical profilometry to measure the film thickness and estimate the growth rate. The comparison of structural and optical properties of samples grown with and without NH3 presence in the gas mixture showed that the ammonia addition allows a better control of nitrogen incorporation in the film structure, while increasing film transparency and reducing the growth rate.