Localization, Coulomb interactions and electrical heating in single-wall carbon nanotubes/polymer composites

摘要

Low field and high field transport properties of carbon nanotubes/polymercomposites are investigated for different tube fractions. Above the percolationthreshold f_c=0.33%, transport is due to hopping of localized charge carrierswith a localization length xi=10-30 nm. Coulomb interactions associated with asoft gap Delta_CG=2.5 meV are present at low temperature close to f_c. We arguethat it originates from the Coulomb charging energy effect which is partlyscreened by adjacent bundles. The high field conductivity is described withinan electrical heating scheme. All the results suggest that using compositesclose to the percolation threshold may be a way to access intrinsic propertiesof the nanotubes by experiments at a macroscopic scale.