Alignment dependence of one-dimensional electronic hopping transport observed in films of highly aligned, ultralong single-walled carbon nanotubes

Abstract

The temperature dependent electrical conductivity of highly aligned, as-grown, pristine films of ultralong single-walled carbon nanotubes (SWNTs) is investigated in the framework of conduction based on phonon-assisted electron hopping. A change in transport mechanism occurs between conduction normal to and parallel to the SWNT alignment that results in evolution from bulk three-dimensional (3D) hopping conduction to a one-dimensional (1D) hopping conduction mechanism intrinsic to the electronic structure of SWNT. Vacuum annealing is observed to change the magnitude of the film conductivity but does not alter the observed 1D or 3D hopping mechanism.