Electron-phonon effects and transport in carbon nanotubes

TL;DR

This paper models electron-phonon interactions in semiconducting carbon nanotubes, revealing how these effects influence mobility, velocity saturation, and band-gap renormalization, with implications for nanotube electronic properties.

Contribution

It provides a detailed calculation of electron-phonon scattering, mobility, and polaronic effects in carbon nanotubes using a tight binding and Boltzmann approach, highlighting new insights into their transport behavior.

Findings

Mobility depends on temperature, electric field, and chirality.

Velocity saturates at about half the graphene Fermi velocity.

Polaronic binding causes a ~70 meV band-gap renormalization.

Abstract

We calculate the electron-phonon scattering and binding in semiconducting carbon nanotubes, within a tight binding model. The mobility is derived using a multi-band Boltzmann treatment. At high fields, the dominant scattering is inter-band scattering by LO phonons corresponding to the corners K of the graphene Brillouin zone. The drift velocity saturates at approximately half the graphene Fermi velocity. The calculated mobility as a function of temperature, electric field, and nanotube chirality are well reproduced by a simple interpolation formula. Polaronic binding give a band-gap renormalization of ~70 meV, an order of magnitude larger than expected. Coherence lengths can be quite long but are strongly energy dependent.