Nucleation on an Intermediate Layer of Metal Carbides

Diamond can nucleate on foreign surfaces, notably elements that form refractory carbides (Si, Mo, Ta, W), without pretreatment. 

Thermodynamics calculations reveal that, in the absence of a plasma, SiC (as opposed to diamond or graphite) is the only stable phase expected on a heated Si substrate under conditions of 0.3 vol.% CH4 in H2, 30 ton-pressure, and 1000°C substrate surface temperature. 

Badzian and Badzianl suggested that diamond nucleation on Si is preceded by the formation of a p-SiC buffer layer, and diamond nucleation occurs on the surface of the carbide. This is supported by many growth experiments of diamond particles or films on Si substrates in HFCVD and 

Joffreau et al. and Lindlbauerl conducted systematic studies of diarriond growtli on carbide-fonrung refractory metals and observed that diamond nucleation occurred only after the formation of a thin carbide layer. Lux and Haubnerf subsequently postulated a model to elucidate the 

The formation of SiC on Si substrates in the initial stages of nucleation was also observed by Waite and Shaht 1 in MW PACVD using XPS. A diamond peak appeared after the incubation period with a simultaneous decrease in SiC peak intensity. However, SiC remained as an impurity even after several hours of deposition. 

---