Growth characteristics of carbon nanotubes by plasma enhanced hot filament chemical vapor deposition

We successfully obtained vertically aligned multiwalled carbon nanotubes on different nickel-coated substrates by plasma enhanced hot filament chemical vapor deposition at low temperatures below 650°C. Acetylene and ammonia gas were used as the carbon source and a catalyst. The surface roughness of the nickel layer increased as NH3 etching time increased. The diameters of the nanotubes decreased and the density of nanotubes increased as NH3 etching time increased. The diameter of the nanotubes was 30–70 nm. A nickel cap was observed on the top of the grown nanotube and a very thin amorphous-carbon-like layer was found on the nickel cap. The morphology and microstructure of carbon nanotubes were measured using scanning electron microscopy and transmission electron microscopy.