Hopping conduction in disordered carbon nanotubes |
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Authors: | D.P. Wang D.E. Feldman A.J. Yin J.M. Xu A. Zaslavsky |
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Affiliation: | a Department of Physics, Brown University, Providence, RI 02912, United States b Division of Engineering, Brown University, Providence, RI 02912, United States |
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Abstract: | We report electrical transport measurements on individual disordered multiwalled carbon nanotubes, grown catalytically in a nanoporous anodic aluminum oxide template. In both as-grown and annealed types of nanotubes, the low-field conductance shows an exp[−(T0/T)1/2] dependence on temperature T, suggesting that hopping conduction is the dominant transport mechanism, albeit with different disorder-related coefficients T0. The electric field dependence of low-temperature conductance behaves as exp[−(ξ0/ξ)1/2] at high electric field ξ at sufficiently low T. Finally, both annealed and unannealed nanotubes exhibit weak positive magnetoresistance at . Comparison with theory indicates that our data are best explained by Coulomb-gap variable-range hopping conduction and permits the extraction of disorder-dependent localization length and dielectric constant. |
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Keywords: | 73.63.Fg 72.20.Ee 72.80.Ng |
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