Synthesis of large area aligned carbon nanotube arrays from C2H2-H2 mixture by rf plasma-enhanced chemical vapor deposition

Large area aligned carbon nanotube (CNT) arrays have been successfully synthesized from C2H2 and H-2 mixture by rf plasma-enhanced chemical vapor deposition (without hot filament) on iron-coated silicon substrates. H-2 plasma (not H-2 gas) was confirmed to play the role of reducing iron oxide to metallic iron and promoting the formation of evenly separated particles, as well as being the primary factor in synthesizing aligned CNTs. The addition of H-2 gas with no plasma during the growth resulted in randomly oriented CNTs. Meanwhile, without the addition of H-2, the C2H2 plasma resulted in the growth of very fine worm-like carbon fibers. Using substrates with a thicker catalyst layer (> 90 nm) reduced the CNT density significantly. (C) 2001 American Institute of Physics.