Bandgap modulation of narrow-gap carbon nanotubes in a transverse electric field

TL;DR

This paper introduces a method to modulate the bandgaps of quasi-metallic carbon nanotubes using a transverse electric field, accounting for curvature effects with tight-binding calculations, revealing quadratic decrease and subsequent expansion of bandgaps.

Contribution

It incorporates curvature effects into bandgap modulation analysis of carbon nanotubes using tight-binding models with $$- and $$-orbitals, providing a more comprehensive understanding.

Findings

Small curvature-induced bandgaps decrease quadratically with electric field

Bandgaps expand again at higher electric fields

Analytical calculations confirm numerical results

Abstract

We propose a method to modulate the bandgaps in quasi-metallic carbon nanotubes using a transverse electric field. Unlike previous investigations, we include curvature effects of the nanotubes by incorporating both $\pi$- and $\sigma$-orbitals in our tight-binding calculations. The calculations show that the small curvature-induced bandgaps decrease quadratically with electric field amplitude to zero. As the electric field amplitude continues to increase, the bandgap then expands in a similar manner to that presented in earlier studies. The bandgap dependence is verified by analytical calculations, which also agree with preceding analyses for the limit of no curvature.