S. Prawer et al., SYSTEMATIC VARIATION OF THE RAMAN-SPECTRA OF DLC FILMS AS A FUNCTION OF SP(2)-SP(3) COMPOSITION, DIAMOND AND RELATED MATERIALS, 5(3-5), 1996, pp. 433-438
We report the Raman spectra of a set of hydrogen-free diamond-like car
bon (DLC) films prepared under conditions that result in different typ
es of carbon bonding and for which the sp(2):sp(3) content was indepen
dently determined by electron energy loss spectroscopy. The films were
prepared using a mass selected C+ ion beam deposition system covering
the ion energy range 10 eV to 20 keV. Previous measurements have show
n that the sp(2) component of the films decreases as the ion energy is
increased from about 10 to 300 eV. For films made with ion energies i
n excess of 1 keV, the sp(2) component increases with increasing ion e
nergy. The Raman spectra of these films show a broad asymmetric peak w
hich narrows with decreasing sp(2) content. The spectra were fitted wi
th a single skewed lorentzian peak described by the Breit-Wigner-Fano
lineshape. The data presented may serve as a reference for DLC charact
erization. In particular, the parameters from the fits show a strong d
ependence on the sp(2) component of the films which may be used to ide
ntify unambiguously (hydrogen-free) DLC films of low sp(2) content (i.
e. very ''diamond-like'' films).