ELLIPSOMETRIC STUDY OF DIAMOND-LIKE THIN-FILMS

Spectroscopic elipsometry is a non-destructive technique that can provide an accurate optical characterization of diamond-like thin films. The optical properties of hydrogenated amorphous carbon (a-C:H) thin films were obtained by using an automatic spectroscopic ellipsometer (UV-visible) with rotating analyser. a-C:H thin films were deposited on glass substrates by plasma r.f. decomposition of methane, and the influence of deposition temperature, T(s) on the optical properties of these films was studied. The results indicate that the refractive index n exhibits a decrease with increasing T(s) and the extinction coefficient k increases with T(s). The optical gap E(g) abruptly falls from 0.80 eV to 0.25 eV as the deposition temperature exceeds 340-degrees-C. The significant variations in the optical parameters with the deposition temperature provide new evidence on the modifications of material structure and possible changes in the hydrogen content.