Synthesis of carbon nanotubes by CO2-laser-assisted chemical vapour deposition

The field of carbon nanotube research is remarkable not only because of the unique properties of this new material but also because of the various possible schemes of their synthesis and their applications. In the present study, we have explored the suitability of laser-assisted chemical vapour deposition for the formation and growth of carbon nanotubes. A medium-power continuous-wave CO2 laser was employed to irradiate a sensitized mixture of Fe(CO)(5) vapour and acetylene and to simultaneously heat a silicon substrate on which the carbon nanotubes were grown. Scanning and transmission electron microscopy (TEM and HRTEM) as well as atomic force microscopy (AFM) were used to analyze the as-grown films and samples specially prepared on TEM grids and AFM substrates. Carbon nanotubes with different structures (straight, curved and even branched), including single- and multi-walled nanotubes were observed. Some nanotubes were found to be partially filled with a solid material (probably metallic iron) that seems to catalyze the nanotube growth. Some regions of the deposit also revealed the presence of nanoparticles. The present experimental conditions should be suitable to produce locally structured deposits of carbon nanotubes for various applications. (C) 2002 Elsevier Science B.V. All rights reserved.