Modifications of diamond films induced by pulsed laser treatment

Diamond thin films promise excellent performance in several application fields such as high temperature and high frequency electronics, but practical applications are presently limited by the polycrystalline morphology of deposited films. A laser treatment was performed to smooth the surface of diamond films, produced by HFCVD, with the aim to allow a suitable patterning and tayloring of diamond films and their use as coatings on specific tools. Different laser wavelengths (193, 532 nm), times of exposure, and energy densities were employed during the treatments. A SEM characterization has shown a structural modification of the surface morphology and a noticeable weakening of surface roughness. A microRaman analysis indicated the appearance of a glassy carbon component which, together with the surface smoothing occurring at the treated zone, seems to justify: a) the large reduction of the intensity of Raman spectra (the diamond and silicon optical phonon lines and the photoluminescence emission are about 50 times weaker); b) the enhancement of conductivity and reflectivity.