CLARIFICATION OF THE EFFECT OF BIAS IN THE HOT FILAMENT PROCESS

The effect of applying d.c. and a.c. bias in the hot-filament process was investigated using in situ rate determination. Biasing the substrate 150 V positive relative to the filament caused a rise in substrate temperature. Adjusting the filament power to maintain a constant substrte temperature when applying the bias did not increase the deposition rate. A bias of less than 120 V did not affect the deposition rate. The positive substrate bias resulted in a slightly higher nucleation density and shortened the incubation time to reach steady state growth but also decreased the diamond quality.