DIAMOND SYNTHESIS ON A METAL-SUBSTRATE

We studied diamond film nucleation phenomena using d.c. plasma jet chemical vapour deposition (CVD). Pt and Cu, which have no carbon atom interaction, generate high density diamond nucleation. W, Mo, Ti, Ta and Nb, which form carbide compounds, generate carbide before nucleation. Ni, Co and Fe, which have a negative energy of carbide formation, generate low density nucleation. These results suggest that diamond nucleation needs a stable surface for the carbon radicals. We developed a new process to increase the nucleation density for low nucleation density substrates. A plasma-sprayed layer, which promotes nucleation, was formed on the substrate surface before diamond synthesis. Both diamond synthesis and the formation of the plasma-sprayed layer can be done by d.c. plasma jet CVD without vacuum leakage.