METASTABLE SYNTHESIS OF DIAMOND

Diamond can be grown metastably at subatmospheric pressures and moderate temperatures from hydrocarbon gases in the presence of atomic hydrogen. Atomic hydrogen serves a number of critical roles in CVD diamond growth, namely: (1) stabilization of the diamond surface, (2) reduction of the size of the critical nucleus, (3) 'dissolution' of carbon in the gas, (4) production of carbon solubility minimum, (5) generation of condensable carbon radicals in the gas, (6) abstraction of hydrogen from hydrocarbons attached to surface, (7) production of vacant surface sites, and (8) etching of graphite. Atomic hydrogen can carry out these functions because of favorable relationships between energies for carbon-carbon, carbon-hydrogen and hydrogen-hydrogen bonds. © 1990.