Reversible Band Gap Engineering in Carbon Nanotubes by Radial Deformation

TL;DR

This paper investigates how radial deformation affects the atomic and electronic structures of carbon nanotubes, demonstrating reversible band gap tuning and insulator-metal transitions through elastic strain.

Contribution

It provides a first-principles analysis of reversible band gap engineering in nanotubes via radial deformation, including elastic properties and electronic response.

Findings

Radial strain can close the band gap, inducing an insulator-metal transition.

Reversible electronic structure tuning is achievable within the elastic range.

Elastic constants are consistent with classical theories.

Abstract

We present a systematic analysis of the effect of radial deformation on the atomic and electronic structure of zigzag and armchair single wall carbon nanotubes using the first principle plane wave method. The nanotubes were deformed by applying a radial strain, which distorts the circular cross section to an elliptical one. The atomic structure of the nanotubes under this strain are fully optimized, and the electronic structure is calculated self-consistently to determine the response of individual bands to the radial deformation. The band gap of the insulating tube is closed and eventually an insulator-metal transition sets in by the radial strain which is in the elastic range. Using this property a multiple quantum well structure with tunable and reversible electronic structure is formed on an individual nanotube and its band-lineup is determined from first-principles. The elastic energy due to the radial deformation and elastic constants are calculated and compared with classical theories.