Charge Transport and Tunneling in Single-Walled Carbon Nanotube Bundles

Abstract

We investigate experimentally the transport properties of single-walled carbon nanotube bundles as a function of temperature and applied current over broad intervals of these variables. The analysis is performed on arrays of nanotube bundles whose axes are aligned along the direction of the externally supplied bias current. The data are found consistent with a charge transport model governed by the tunneling between metallic regions occurring through potential barriers generated by a nanotube's contact areas or bundle surfaces. Based on this model and on experimental data, we describe quantitatively the dependencies of the height of these barriers upon bias current and temperature.

Fluctuation-induced tunneling conduction through nanoconstrictions

“…III. This is in contrast to the results observed recently in CNT samples, 5 where the agreement between the two-probe and four-probe results indicates the measured characteristics to be intrinsic to the bulk sample, i.e., arising from CNT-CNT contacts. Details of some of the calculations are given in Appendixes A and B.…”

“…In the original FITC model, 1,5,6 the resistance-temperature relation has the following characteristic expression…”

“…The FITC can successfully explain the nonmetallic temperature dependence of conductivity in diverse materials such as carbonpolyvinylchloride films, tin-doped indium oxide ͑ITO͒ thin films, carbon nanotube ͑CNT͒ bundles, and conducting polymers. [2][3][4][5] These materials share the common trait that, other than the nonmetallic temperature variation in the conductivity, other properties, e.g., optical characteristics, all exhibit metallic behavior.…”

Macroscopic effects of tunnelling barriers in aggregates of carbon nanotube bundles

“…The FIT model predicts a temperature dependence of the electrical resistance given by R = R 0 e T 1 /(T +T 2 ) where T 1 is proportional to the potential barrier, T 2 is the temperature below which FIT regime is active and R 0 is the resistance at a given temperature. Setting R 0 = 12.7 k (the resistance of the sample at 240 K) in our case T 1 = 204 K and T 2 = 30 K give the best fit of the R-T data in agreement with previous results [10]. It is worth noting that the variable range hopping (VRH) model [8], successfully employed in several CNTs systems, does not fit our experimental data in the whole temperature range investigated.…”

Internal resonance of vibrational modes in single-walled carbon nanotubes

“…The vibrational characteristics of carbon nanotubes (CNTs) have been studied extensively because of their importance in nanomechanical devices and sensoring applications (Sazonova et al 2004;Salvato et al 2008;Wang et al 2008). The vibrations of CNTs can be measured using X-ray diffraction and Raman spectroscopy, and these measurements usually focus on a radial breathing mode (RBM) and other higher frequency modes (D, G and G bands;Dresselhaus & Eklund 2000;Dresselhaus et al 2002Dresselhaus et al , 2007Tang et al 2008).…”