Transport Properties of SW and MW Carbon Nanotube Bundles

Transport properties of single and multiwalled carbon nanotubes, with the tube axes aligned along the bias current direction, have been studied as a function of the temperature and applied current. The experimental data are consistent with a model of charge transport governed by tunnel between potential barriers created at the connection between the nanotubes or bundles surfaces and modulated by thermal fluctuations. A current dependence of the potential energy for both single and multiwalled samples that gives indications the charge transport mechanism inside these materials has been obtained. Moreover, the values of the potential energy found, less for multiwalled with respect to the single walled nanotubes, confirm the presence of a metallic component in the samples as shown from the temperature dependence resistivity data.