Growth of Vertically Aligned Single-Walled Carbon Nanotubes on Alumina and Sapphire Substrates

The synthesis of vertically aligned carbon nanotubes with submillimeter-order heights was performed using ethanol chemical vapor deposition with Co catalysts supported on Al 2 O 3 substrates. The effects of Al 2 O 3 in the form of amorphous alumina and single-crystalline sapphire were investigated through a characterization of the Co catalyst particles on the substrates. An important effect of Al 2 O 3 was found to be the production of highly dense and nanosized Co particles, owing to a low surface diffusivity.