Carbon films with high density nanotubes produced using microwave plasma assisted CVD

The preparation of massive carbon nanotubes on silicon, quartz and ceramic substrates using microwave plasma enhanced CVD is reported. The nanotubes, ranging from 10 to 120 nm in diameter and a few tens of microns in length, were formed under hydrocarbon plasma at 720 degrees C with the aid of iron- oxide particles. It is found that the morphology of the nanotubes is strong ly influenced by the now ratio of methane to hydrogen. Defect-less nanotube s with small diameters are favourably produced under a small flow ratio. In contrast, defect-rich nanotubes with large diameters and highly disordered growth directions are formed at a large flow ratio. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.