Enhancement of diamond nucleation using the solid-liquid-gas interface energy

We demonstrate the enhancement of diamond nucleation through the use of the equilibrium forces at the solid-liquid-gas interface on a substrate wetted with droplets of an oil of low vapor pressure. Such a process is shown to produce well-faceted grains with densities of roughly 10(7) nuclei cm(-2) (boundary), 10(5) nuclei cm(-2) (oil-coated area), and 10(4) nuclei cm(-2) (uncoated area) without the need for scratching or seeding the substrate. Diamond deposition was undertaken on silicon using ethanol and hydrogen in the feed of a hot-filament chemical vapor deposition reactor. The oil-covered regions, in addition to showing higher nucleation densities, have the merit that the intergrain spaces are covered with diamond structures, while the parts uncovered with oil exhibit intergrain spaces covered with diamond-like carbon. (C) 2000 American Institute of Physics. [S0021- 8979(00)03515-5].