Direct quantitative detection of the sp3 bonding in diamond-like carbon films using ultraviolet and visible Raman spectroscopy

Abstract

The bonding in a series of unhydrogenated amorphous carbon films has been analyzed quantitatively using Raman spectroscopy excited by laser light in both the visible and ultraviolet regions of the spectrum. The asymmetry of the peak near 1550 cm-1 in the visible Raman spectra is correlated with the percentage of sp3 bonding in the films. The ultraviolet Raman spectra exhibit two broad Raman peaks at 1650 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 phonon density-of-states for the distorted random network of sp3 sites. The position and relative intens..