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Effects of Catalyst Layers on Carbon Nanotubes Growth

Carbon nanotubes growth on varied thicknesses of nickel catalyst by hot filament chemical vapor deposition (HFCVD) is reported. The nanotubes were grown using C2H2 acetylene as carbon feedstock in hydrogen and nitrogen atmosphere. The catalyst layers were deposited by magnetron sputtering technique with thicknesses varied from 25 nm to 200 nm. Deposited films were annealed at 600 °C for 10 min before exposing to C2H2 for the growth of nanotubes at same temperature for another 10 min. The effects of catalyst thickness have been investigated with reference to nanotubes formation. The morphology and microstructure of the films were measured and analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Raman analysis was also conducted to determine the atomic bonding structure of nanotubes. The catalyst thickness has significant effects on the nanotubes alignment and the uniformity of nanotube diameters. However, the thickness shows no obvious effects on the atomic structure of the nanotubes grown.