The deposition of oriented diamond film by hot-filament chemical vapor deposition with separate reactant gas

A (110)-oriented diamond film was deposited by hot filament chemical vapor deposition with H2 and CH4 separately introduced into the reactive zone. The film with a degree of orientation I(220)/I(111) of more than 200% and deposition rate of 2–3 μm/h was obtained for a deposition time of 17 h. The long deposition time enlarged the grain size and enhanced the degree of orientation, but too long a deposition time resulted in random growth. The temperature field was measured and also calculated using a simple model. Both results showed that a temperature field existed with varied gradients along the normal of substrate surface. The (110)-oriented diamond film was deposited in the zone with negative temperature gradient. The change in orientation occurring for long deposition times was ascribed to the change of temperature gradient.