SYNTHESIS OF DIAMOND FILMS ON TITANIUM SUBSTRATES BY HOT-FILAMENT CHEMICAL VAPOR-DEPOSITION

Synthetic diamond film has been deposited on a polycrystalline titanium substrate using a hot-filament chemical vapor deposition method in order to study the role of substrate pretreatment and carbide formation for the diamond nucleation and subsequent growth. The substrate pretreatment, roughening by diamond powder, affects both nucleation behavior and subsequent growth of diamond. The TiC is formed on the Ti substrate during deposition. It is observed that scratches which existed on the initial Ti surface disappear after the TiC has formed; this TiC has a rough and porous structure. The TiC layer formed in this experimental condition does not influence the nucleation behavior. The nucleation behavior depends entirely on the initial surface condition of the Ti substrate, i.e., whether or not it was scratched with the diamond powder. It is suggested that changes in the surface nature due to the scratching process can create the new nucleation sites which have strong binding energies and that the formation of these new sites can alter the nucleation behavior.