NUCLEATION OF CHEMICALLY VAPOR-DEPOSITED DIAMOND ON PLATINUM AND NICKEL SUBSTRATES

Diamond growth on platinum and nickel substrates, both scratched and unscratched, was examined over a wide variety of growth conditions in an effort to understand the nucleation mechanism of diamond. The experiments used a combination of X-ray photoelectron spectroscopy, electron energy loss spectroscopy, and low energy electron diffraction to examine the time evolution of surface carbon species during diamond growth. Samples were transferred under vacuum from the filament-assisted diamond growth chamber to an attached ultrahigh vacuum analytical chamber. Our results indicate that diamond nucleates on platinum and nickel by pre-deposition of graphitic carbon precursors. Defect sites in these graphite deposits contain the nucleation sites for diamond. These nucleation sites are sensitive to the presence of gas phase oxygen species; therefore, addition of oxygen to the gas phase suppresses diamond nucleation by elimination of the nucleation sites but does not suppress growth of existing diamond. Our results demonstrate at least one mechanism whereby diamond can nucleate on metallic substrates such as platinum and nickel.