Diamond nucleation and growth on refractory metals using microwave plasma deposition

Mo, W, Nh and Ta sheets are widely used as substrates for diamond deposition. These metals are carburized on the surface and this reaction influences diamond nucleation. Diamond growth, however, is not influenced since the vapor pressure of the carbides is very low. Polishing powder remaining on the substrate surface after surface treatment as well as the surface roughness influence the diamond nucleation. The substrates were pretreated with various polishing powders (diamond, B4C, SiC, Al2O3) of different grain sizes (1-50 mu m). The influences of these pretreatments on subsequent diamond nucleation and deposition were then investigated.