Nucleation of chemical vapor deposited diamond from graphitic carbon

Diamond nucleation was studied in a hot-filament assisted chemical vapor deposition reactor. It was found that graphite powder greatly enhances diamond nucleation. Scanning electron microscopy showed a strong preference of diamond nucleation on graphite edges. Electron diffraction patterns taken from diamond deposited on highly oriented pyrolytic graphite substrate showed the following orientation relationship: (111);This means that the six-membered rings in the ;A stick and ball model in which three diamond ;The work provides full support for the proposed nucleation mechanism that diamond nucleates through graphitic carbon. The graphitic carbon edge atoms that are hydrogenated by H serve as diamond precursors. This nucleation mechanism is consistent with the empirical nucleation rules of Ostwald and Volmer. A thermodynamic calculation showed that the graphitic carbon, which is the less dense phase, also becomes the less stable carbon phase under an atomic hydrogen atmosphere.;Interactions between a Si substrate and the deposition environment were studied. The possible effect of this interaction on diamond nucleation is discussed. A simplified calculation of atomic hydrogen coverage on diamond surfaces was also made.