Study on Variable Range Hopping and/or Phononassisted Tunneling Mechanism of Electronic Transport in Polymers and Carbon Nanotubes

We review and compare two models recently used to describe electronic transport in polymer
fibers/nanotubes and carbon nanotubes including graphene nanoribbons, namely, variable range
hopping (VRH) in different versions and their modifications on the one hand and electric-field-induced
phonon-assisted tunneling (PhAT) on the other hand. The VRH model is mainly approved on behalf of
the results of temperature dependences. However, the field dependencies of the conductivity in the
framework of this model remain practically unexplained. At the same time, the PhAT model describes
properly not only temperature dependence of conductivity measured in a wide temperature range, but
also conductivity/current dependences on field strength using the same set of parameters
characterizing the materials. The presented PhAT theoretical approach provides a deeper insight into
the physical background of the charge transport through barriers in a wide range of organic and
inorganic devices.