Metallic conductivity in bamboo-shaped multiwalled carbon nanotubes

Temperature-dependent resistivity measurements were carried out on bamboo-shaped multiwalled carbon nanotubes (MWNTs) grown by thermal chemical vapor deposition. They were deposited on Al2O3/Ti and SiO2/Ti substrates using cobalt and iron catalysts, respectively. As a result, a metallic conductivity, i.e. resistivities with a positive temperature slope, was observed for the MWNTs grown on the SiO2/Ti substrates. The different temperature behaviors of the resistivity for the MWNTs grown on different substrates are discussed in view of the substrate morphology and crystallinity.