Raman diagnostics of amorphous diamond-like carbon films produced with a mass-separated ion beam

Raman spectra of the amorphous hydrogen-free diamond-like films prepared in well-controlled conditions by using a mass-separated carbon ion beam are investigated. The Raman spectra of a series of samples deposit-ed by the same mass-separator set-up but with different energies of carbon ions and characterized by different sp(3) fractions are compared. The correlation between the sp(3) fraction and the numerical parameters of Raman spectra recorded in the 100-4100 cm(-1) range, such as (i) the intensity ratios R-(1) = I-500/I-1500, R-(2) = I-2100/I-3000, R-(3) = I-2100/I-1550 and (ii) the average slope S = (I-1300-I-1100)/I-1100, is established for each of the five wavelengths of Ar+ laser excitation. Possible interference distortion of the shape of Raman spectra is taken into account, The presented results agree with the theoretically predicted properties of tetrahedral amorphous carbon and confirm the possibility of the effective quantitative characterization of this material by using Raman spectroscopy, The correlations obtained are used for practical studies of spatial properties of the film structure and a significant decrease of the film duality towards the edges of diamond-like film is observed. (C) 1997 Elsevier Science S.A.