Plasma-induced alignment of carbon nanotubes

Uniform films of well-aligned carbon nanotubes have been grown using microw ave plasma-enhanced chemical vapor deposition. It is shown that nanotubes c an be grown on contoured surfaces and aligned in a direction always perpend icular to the local substrate surface. The alignment is primarily induced b y the electrical self-bias field imposed on the substrate surface from the plasma environment. It is found that switching the plasma source off effect ively turns the alignment mechanism off, leading to a smooth transition bet ween the plasma-grown straight nanotubes and the thermally grown "curly" na notubes. The nanotubes grow at a surprisingly high rate of similar to 100 n m/s in our plasma process, which may be important for large-scale commercia l production of nanotubes. (C) 2000 American Institute of Physics. [S0003-6 951(00)02532-8].