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The effects of surface pretreatments on the nucleation of diamond on silicon substrates have been studied by quantitative x-ray photoelectron spectroscopy measurements. It was found that methods of surface pretreatments including ultrasonic abrasion, scratching, and dc biasing all introduced a substantial amount of carbon species to the substrate surface which was the primary reason for the enhancement of diamond nucleation. Both the scratching and biasing processes formed carbide on the Si surface which also facilitated diamond nucleation. In addition, the biasing process reduced and suppressed the formation of oxide which further contributed to the enhanced nucleation density of diamond. This analysis is consistent with the experimental data of nucleation densities of diamond on the differently pretreated substrate surfaces both observed in this study and found in the literature.

X-ray photoelectron spectroscopy was used to investigate how different pretreatments modify the chemical composition and bonding on silicon substrate surface and, to detect the intermediate phases present at the diamond film interface. The pretreatments were mechanical scratching with a diamond powder, ultrasonic abrasion with diamond suspension and in siru negative dc biasing. The XPS results indicated the presence of hydrocarbons and the formation of new chemical species on the Si substrates such as oxides and carbides. The very important role played by silicon carbide on diamond nucleation and growth was underlined by the phases found at the diamond films interface.

Diamond deposition on group VIII transition metals of Cr, Mn, Fe, Co, and Ni has been achieved by a multi-step chemical vapor deposition process consisting of (i) seeding the substrate with diamond powders, (ii) annealing the seeded substrate in hydrogen at high temperatures, and (iii) diamond nucleation and growth. It was found that high quality diamond can be grown on these substrates, and the often accompanied graphite formation, which has been the main obstacle in the deposition of diamond on these metal surfaces, can be largely suppressed by the above step-deposition procedure. This technique was further extended to the processes of depositing diamond on steels and Co-bonded WC materials.

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