We investigated the growth characteristics of the nanocrystalline diamond films using CCl4/H-2 as gas sources in a hot-filament chemical vapor deposition (CVD) reactor. Successful growth of nanocrystalline diamond at typical growth condition of 1.5-2.5% CCl4 and 550-730 degreesC substrate temperature has been demonstrated. Glancing angle X-ray diffraction (XRD) clearly indicated the formation of diamond in the films. Typical root-mean-square surface roughness of 10-15 nm and an optimal root-mean-square surface roughness of 6 nm have been achieved. Transmission electron microscopy (TEM) analyses indicated that nanocrystalline diamond film with an average grain size in the range of 10-20 nm was deposited from 2.5% CCl4/H-2 at 610 degreesC. Effects of different source gas composition and substrate temperature on the grain nucleation and grain growth processes, whereby the grain size of the nanocrystalline film could be controlled, were discussed. (C) 2004 Elsevier B.V. All rights reserved.