Particle size dependence and model for iron-catalyzed growth of carbon nanotubes by thermal chemical vapor deposition

The catalytic particle size dependence of chemical vapor deposition (CVD) growth of multiwall carbon nanotubes (MWNT) was investigated using C₂H₂ and C₆₀ as carbon feedstock gases. Catalytic iron films of controlled thickness between 0.5 and 20 nm were deposited on a clean SiO₂ surface. Atomic force microscope (AFM) imaging of the annealed iron films was used to determine the iron particle size distributions. It was concluded that for thermal CVD methods using Fe as the catalyst metal, the MWNT size distribution is only slightly sensitive to the catalysts size in the range of ten to a few hundred nm.