Plasma deposition of a-C/H films - the role of process gas, plasma chemistry and plasma surface interaction

Raman and photoluminescence spectroscopy are reviewed and discussed as tools for the characterization of hydrogenated amorphous carbon (a-C:H) films. Thereby emphasis is laid on hard, strongly cross-linked films. Photoluminescence provides a quick measure for the film characteristic, either hard or soft and "polymerlike". Raman spectroscopy allows the analysis of extremely thin a-C:H films down to a layer thickness of approximate 10 A as well as the study of the film-substrate interface. Using electronic resonance effects Raman scattering gives insight into the microscopic structure of the films. In hard a-C:H experimental evidence is found for clustered sp2 sites connected by sp3 carbon. (IAF