Electronic response and bandstructure modulation of carbon nanotubes in a transverse electrical field

TL;DR

This paper studies how a transverse electric field affects the electronic properties and bandstructure of carbon nanotubes, revealing bandgap modulation and the dependence on tube symmetry, radius, and doping levels.

Contribution

It provides a detailed analysis of the electronic response of carbon nanotubes under transverse fields using a tight-binding model, highlighting symmetry-dependent effects and bandstructure modifications.

Findings

Bandgap opening/closing predicted for zigzag nanotubes.

Armchair nanotubes remain metallic regardless of the field.

Large fields cause significant bandstructure mixing.

Abstract

The electronic properties of carbon nanotubes in a uniform transverse field are investigated within a single orbital tight-binding model. For doped nanotubes, the dielectric function is found to depend not only on symmetry of the tube, but also on radius and Fermi level position. Bandgap opening/closing is predicted for zigzag tubes, while it is found that armchair tubes always remain metallic, which is explained by the symmetry in their configuration. The bandstructures for both types are considerably modified when the field strength is large enough to mix neighboring subbands.