Transport in Nanotubes: Effect of Remote Impurity Scattering

TL;DR

This paper develops a theoretical model for remote Coulomb impurity scattering in single-wall carbon nanotubes, analyzing how it affects electrical conductivity based on bandstructure and Fermi level, with implications for high mobility in doped tubes.

Contribution

It introduces a detailed theoretical framework for impurity scattering in nanotubes, including analytical and numerical results on conductivity and scattering rates.

Findings

Conductivity exhibits exponential dependence on Fermi energy.

Degenerately doped semiconductor nanotubes can achieve high mobility.

Inter-subband transitions can limit electron transport at high doping levels.

Abstract

Theory of the remote Coulomb impurity scattering in single--wall carbon nanotubes is developed within one--electron approximation. Boltzmann equation is solved within drift--diffusion model to obtain the tube conductivity. The conductivity depends on the type of the nanotube bandstructure (metal or semiconductor) and on the electron Fermi level. We found exponential dependence of the conductivity on the Fermi energy due to the Coulomb scattering rate has a strong dependence on the momentum transfer. We calculate intra-- and inter--subband scattering rates and present general expressions for the conductivity. Numerical results, as well as obtained analytical expressions, show that the degenerately doped semiconductor tubes may have very high mobility unless the doping level becomes too high and the inter--subband transitions impede the electron transport.