Local Semiconducting Transition in Armchair Carbon Nanotubes: The Effect of Periodic Bi-site Perturbation on Electronic and Transport Properties of Carbon Nanotubes

TL;DR

This paper demonstrates that periodic bi-site defect clusters in armchair carbon nanotubes can induce a band gap, effectively turning metallic nanotubes into semiconductors, with implications for nanoelectronic device design.

Contribution

It reveals how periodic bi-site perturbations can open a band gap in armchair nanotubes, providing a new method to control their electronic properties.

Findings

Periodic defect clusters induce a band gap in armchair nanotubes.

The band gap depends on the periodicity of the defect clusters.

Length and randomness of defected regions influence electron transport.

Abstract

In carbon nanotubes, the most abundant defects, caused for example by irradiation or chemisorption treatments, are small perturbing clusters, i.e. bi-site defects, extending over both A and B sites. The relative positions of these perturbing clusters play a crucial role in determining the electronic properties of carbon nanotubes. Using bandstructure and electronic transport calculations, we find out that in the case of armchair metallic nanotubes a band gap opens up when the clusters fulfill a certain periodicity condition. This phenomenon might be used in future nanoelectronic devices in which certain regions of single metallic nanotubes could be turned to semiconducting ones. Although in this work we study specifically the effect of hydrogen adatom clusters, the phenomenon is general for different types of defects. Moreover, we study the influence of the length and randomness of the defected region on the electron transport through it.