Growth-temperature induced metal–insulator transition in bamboo-shaped multiwalled carbon nanotubes

Temperature-dependent resistivity measurements were carried out on bamboo-shaped multiwalled carbon nanotubes (CNT) grown on cobalt-catalyst-deposited A12O3/Ti substrates by a thermal chemical vapor deposition. The resistivity decreased with increasing growth temperature, and a reduced activation energy analysis showed that the CNT moved from the critical regime to the metallic regime with increasing growth temperature. The improved electrical conductivity with increasing growth temperature is attributed to the improved crystallinity and the increased diameters of the CNT.