ANALYSIS OF THE INTERMEDIATE LAYERS GENERATED AT THE FILM-SUBSTRATE INTERFACE DURING THE CVD PROCESS OF DIAMOND SYNTHESIS

In the present work the structural characteristics of diamond films, obtained by means of Hot Filament Chemical Vapour Deposition (HFCVD), on various substrates (glassy carbon, soda-lime glass, and titanium) are correlated with the formation of different intermediate carbonaceous layers at the film/substrate interface. The surface morphology of the diamond was studied by electron microscopy, whereas the structural characteristics of the intermediate layers were investigated by means of reflection high-energy electron diffraction (RHEED) and X-ray powder diffraction (XRPD) techniques. Graphite-like and amorphous structures, respectively, were identified at the interface with glassy carbon and soda-lime glass substrates. RHEED and Grazing Incidence X-ray Diffraction measurements allowed us to determine the stratification sequence of the intermediate carbonaceous layers grown on Ti. The XRPD technique was used to study the growth kinetics of diamond, TiC and TiH2 layers during the coating process. The features of diamond nucleation on the various substrates are discussed with reference to the structure of carbonaceous transition layers formed at the substrate/film interface.