EVIDENCE OF RAPID EQUILIBRATION NEAR THE HOT-FILAMENT IN DIAMOND DEPOSITION

Chemical composition of the gas phase during the diamond growth by a hot-filament method was measured gaschromatographically for two different configurations with feed gas introduction, the conventional method from a nozzle equipped on a reactor wall and the jet feed from a hole bored in a substrate located just beneath the filament. CH4 and C2H2, diluted in H-2, were used as a source gas. The results indicated that equilibration took place so rapidly near the filament that even the jet-feed mixture was converted to a thermodynamically stable composition composed mainly of C2H2, H, and H-2. Insensitivity of the diamond process to the source hydrocarbon and its sensitivity to the filament-and-substrate configuration can be well interpreted.