Microstructural properties of amorphous carbon nitride films synthesised by dc magnetron sputtering

Amorphous carbon nitride (a-C:N) films have been prepared on silicon(1 0 0) substrates by direct current magnetron sputtering of graphite using a gaseous mixture of Ar and N2. Raman spectra have shown that these a-C:N films have a graphitic structure. The incorporation of nitrogen in the films has been confirmed by Fourier transform infrared (FTIR) spectroscopy. Graphitic and disordered sp2-bonded carbon which are present in Raman spectra and are normally forbidden (not observed) in FTIR become infrared active in our films as the symmetry of the hexagonal carbon rings is broken by nitrogen incorporation. X-ray photoelectron spectroscopy has been used to study the type of chemical bonding in these a-C:N films. The C 1s and N 1s X-ray photoelectron peaks have been deconvoluted and studied. We have found that for the CN and CN components of the C 1s and N 1s photoelectron peaks, there is a maximum peak intensity ratio of CN:CN in the films deposited when the gaseous mixture contains 35% N2 in the sputter gas.