Low-field semiclassical carrier transport in semiconducting carbon nanotubes

Abstract

The theory of semiclassical carrier transport in semiconducting single-walled carbon nanotubes is presented. The focus is on transport in response to a small, axially applied field. Carriers are considered to scatter with longitudinal, torsional, and radial breathing acoustic phonons. Theory predicts large mobilities and large mean free paths, each increasing with increasing tube diameter. This results from a small effective mass, which varies inversely with the nanotube diameter. In large diameter tubes, the carrier mobility at $300\mathrm{K}$ is approximately ${10}^5{\mathrm{cm}}^2\mathrm{V}\mathrm{s}$, while the mean free path approaches $0.5-0.8\mu \mathrm{m}$. Results depend on the lattice temperature, Poisson’s ratio, and the chirality angle of the nanotube. Theoretical results compare very well with experiments on long semiconducting carbon nanotubes. This indicates that transport in long single-walled carbon nanotubes is likely limited by phonon scattering at temperatures above $\approx 200\mathrm{K}$.