Plasma synthesis of well-aligned carbon nanocones

Abstract

Deposition of well-aligned carbon nanocone array has been achieved on catalytically patterned Si (100) substrates by direct current (DC) plasma-enhanced chemical vapor deposition method using acetylene and ammonia mixtures. It was found that the high concentration of acetylene utilized in the growth transformed the cylinder shape of carbon nanotubes into cones. Examination of these conical nanostructures using TEM revealed that they consist of a bundle of crystalline bamboo-like carbon nanotubes that exhibited a graded increase in heights from the periphery to the center. Focused He-Ne laser was used to cut the cone and expose the internal nanotube bundles. A mechanism based on restricted diffusion of precursors to the inner nanotube has been proposed to explain the growth of the nanocone. We found that the nanocone array is mechanically stiff in solution, and the hexagonal nanocene array can be imaged by an atomic force microscope. © 2004 Published by Elsevier B.V.