IR ATTENUATED TOTAL REFLECTANCE STUDIES OF DC BIASED GROWTH OF DIAMOND FILMS

The IR spectra of polycrystalline diamond films grown under negative d.c. biased conditions were recorded using both conventional transmission and total internal reflectance spectrometry. The films were grown by microwave enhanced plasma deposition on single-crystal silicon using methane-hydrogen mixtures at powers of up to 0.8 kW. IR spectra in the carbon-hydrogen stretching region were recorded over the wavenumber range 4800-400 cm-1 using Fourier transform techniques. The profiles of the IR bands of the biased and non-biased samples showed the presence of differing carbon-hydrogen groupings. In the non-biased samples only hydrogen bound to sp3 hybridized carbon was detected. In contrast, the biased films showed the presence of sp2 hybridized C-H groupings for films deposited with a 10% methane in hydrogen mixture. The spectroscopic evidence could not distinguish between the sp2 C-H derived from either graphitic or =CH containing phases. When growth at normal conditions, 0.5% methane in hydrogen, was performed after biased enhanced nucleation, the overall hydrogen content of the film remained similar although the distribution of chemically bound hydrogen amongst the sp3 hybridized CH groupings altered significantly.