Ultraviolet and visible Raman analysis of thin a-C films grown by filtered cathodic arc deposition

Amorphous carbon thin films with a wide range of sp2 fraction from 20 to 90% grown by filtered cathodic arc deposition have been examined by ultraviolet (UV) at 325 nm and visible Raman spectroscopy at 457 nm excitation wavelength. The comprehensive study of behaviour of G, D and T band with sp2/sp3 content has been carried out. The upwards shift of the G peak with sp3 content was observed for both excitation wavelengths. It was also found that the I(D)/I(G) ratio decreases with sp3 content for UV and visible excitations, and for high sp3 content I(D)/I(G) tends to zero. The dispersion of the G peak is also investigated in this work as a function of sp2 content.