Europhys. Lett.
Volume 73, Number 5, March 2006
Page(s) 759 - 764
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 18 January 2006
Europhys. Lett., 73 (5), pp. 759-764 (2006)
DOI: 10.1209/epl/i2005-10446-x

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

D. Gunlycke1, C. J. Lambert2, S. W. D. Bailey2, D. G. Pettifor1, G. A. D. Briggs1 and J. H. Jefferson3

1  Department of Materials, University of Oxford - Parks Road, Oxford, OX1 3PH, UK
2  Department of Physics, University of Lancaster - Lancaster, LA1 4YB, UK
3  Sensors and Electronics Division, QinetiQ - St. Andrews Road, Malvern WR14 3PS, UK

received 18 October 2005; accepted in final form 5 January 2006
published online 18 January 2006

We propose a method to modulate the bandgaps in narrow-gap 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 narrow 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 on metallic nanotubes. The bandgap dependence is verified by analytical calculations, which also agree with preceding analyses for the limit of no curvature.

73.22.-f - Electronic structure of nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals.
73.63.Fg - Electronic transport in nanoscale materials and structures: Nanotubes.
85.35.Kt - Nanotube devices.

© EDP Sciences 2006