Published online by Cambridge University Press: 10 February 2011
The bonding in a series of unhydrogenated amorphous carbon films has been analysed quantitatively using Raman spectroscopy with ultraviolet excitation. The Raman spectra exhibit two broad Raman peaks at 1650 cm−1 and 1100 cm−1, due to sp2 and sp3 vibrational modes respectively. The former is a resonance feature associated with a large proportion of paired sp2 sites, while the latter is a weighted vibrational density-of-states for the distorted random network of sp3 sites. The position and relative intensity of the two peaks are shown to be strongly correlated with the percentage of sp3 sites in the films, providing a reliable measure of sp3 bonding which is both quantitative and non-destructive.