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

D. Gunlycke, C. J. Lambert, S. W. D. Bailey, D. G. Pettifor, G. A. D. Briggs, J. H. Jefferson

Published 2005-10-18, updated 2006-02-02Version 2

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.