Published online by Cambridge University Press: 25 February 2011
We have constructed a novel, sequential DC glow and hot filament CVD reactor, to study the influence of single parameters on the deposition of diamond thin films. This reactor is capable of growing diamond films, with independent excitation of hydrogen and methane. This is achieved by the sequential exposure of the substrate to spatially separated, chemically independent, plasma regions of hydrogen, and methane in helium. The substrate is mounted on a rotating plate above the gas sources at a variable distance, typically 0.5 – 2 mm. The plate is radiantly heated from behind to a desired temperature up to 1300 K. Using the sequential deposition chamber we have been able to deposit good quality diamond up to 8% methane in helium, without the presence of oxygen, by separating a source of atomic hydrogen and a source of methane. These experiments show that methane and atomic hydrogen do not need to be present simultaneously to grow diamond. Our results further indicate that the primary critical parameter for both quality and growth rate, in hot filament deposition of diamond, is the concentration of atomic hydrogen in the system.