Low temperature growths of nanocrystalline diamond films by plasma-assisted hot filament chemical vapor deposition

Nanocrystalline diamond (NCD) films were prepared at a substrate temperature of 650-700 °C by negatively biasing the substrate in a plasma-assisted hot filament chemical vapor deposition system (HFCVD). NCD films with root-mean-square roughness around 12-13 nm and an average grain size of 5 nm were obtained. The growth rate of NCD film was as high as 3 μm/h. Micro-Raman spectroscopy shows clearly a broad peak around 1140 cm− 1, characteristic of nanocrystalline diamond. Transmission electron microscopy (TEM) identified the diamond nanocrystallites. The growth mechanism of the NCD films synthesized at a low temperature is also discussed.