The structural properties of few-walled carbon nanotubes grown by thermal chemical vapor deposition were investigated using high-resolution transmission electron microscopy and Raman spectroscopy. The temperature-dependent conduction mechanism of few-walled carbon nanotube networks were studied at 5 to 200K, and were found to involve a combination of variable-range hopping and fluctuation-induced tunneling. It was further shown by Raman spectra that the conduction mechanism not only depended upon the wall number alone, but was significantly influenced by structural defects.

The Role of Structural Defects on the Transport Properties of a Few-Walled Carbon Nanotube Networks. R.Kamalakannan, K.Ganesan, S.Ilango, N.Thirumurugan, V.N.Singh, M.Kamruddin, B.R.Mehta, A.K.Tyagi: Applied Physics Letters, 2011, 98[19], 192105