Raman characterisation of PIII multilayer carbon films

Abstract Raman studies of thick carbon films (>2 μm) on silicon substrates produced from a cathodic arc plasma by plasma immersion ion implantation (PIII) revealed peaks in addition to the previously identified D, G, D′ triad in the 1200–1600 cm−1 Raman-shift regions. Two ‘G’ peaks were observed in the same spectrum, one of which may be fitted by a Gaussian, the other by a Lorentzian function. We suggest that the ‘G’ peak derived from amorphous carbons should be renamed as ‘A’ (‘amorphous’) peak, leaving the G peak as the term for the true graphitic peak. Cross-sectional spectra show significant differences to planar spectra, including evidence suggestive of C5 and C7 rings and other, perhaps olefinic, structures.