Nucleation and initial growth stages of chemical vapor deposition (CVD) diamond

Nucleation of diamond on non-diamond virgin substrates is characterized by low nucleation densities and long incubation times. Various methods have be en developed to enhance nucleation densities and reduce the duration of inc ubation. This report describes a number of different but related studies of diamond nucleation on silicon and chemically modified silicon surfaces. Th e effect on the initial stages of deposition of mechanical abrasion with sl urries and in-situ sample biasing are especially discussed. Substrate abrasion with diamond results in the embeddying of diamond debris into its surface. Destructive ion implantation into this diamond debris is found to prevent subsequent diamond growth, therefore leading to the concl usion that the diamond debris serves as growth centers. Abrasion of the sub strate with mixed metal/diamond slurries is reported to further enhance nuc leation relative solely to diamond abrasion. It is suggested that during th e chemical vapor deposition (CVD) process some metals alter the composition of the gas phase above the growing surface. Also, the role of surface reac tions is emphasized. We also introduce the de-glow discharge process as a novel, in situ surface pretreatment method for the formation of a precursor for diamond nucleatio n. Our results show that the promotion of diamond growth by this method is primarily due to formation of nano-size diamond particles during the pretre atment process. It is suggested that, to some extent, graphitic carbon with a high degree of defects may serve as a diamond nucleation center as well.