Diamond films have been deposited using a chemical vapour deposition (CVD) technique involving a hybridization of the hot filament and the capacitively coupled radio-frequency (RF) plasma. The changes produced in the surface morphology and Raman spectra of these films are investigated as a function of the magnitude of RF power and deposition chamber pressure. The coupling of low levels of RF power with the hot filament CVD is observed to improve the growth rate as well as quality of the diamond films while higher levels of RF power decreased the growth rate and produced porous films containing needle-shaped microcrystals. These changes are attributed to the ion bombardment of the growing film due to the self-biasing effect of the RF plasma.