Effects of CCl4 concentration on nanocrystalline diamond film deposition in a hot-filament chemical vapor deposition reactor

The effect Of CCl4 concentration on the nanocrystalline diamond (NCD) films deposition has been investigated in a hot-filament chemical vapor deposition (HFCVD) reactor. NCD films with a thickness of few-hundred nanometers have been synthesized on Si substrates from 2.0% and 2.5% CCl4/H-2 at a substrate temperature of 610 degreesC. Polycrystalline diamond films and nanowall-like films with higher formation rates than those of the NCD films were deposited from lower and higher CCl4 concentrations, respectively. The grain sizes of the diamond film grown using 2.0% CCl4 increased with film thickness while a diamond film with uniform nanocrystalline structure all over a thickness of 1 mum can be deposited in the case of 2.5% CCl4. We suggest that both the primary nucleation and the secondary nucleation processes are crucial for the growth of the NCD films on Si substrates. (C) 2004 Published by Elsevier Ltd.