Tuning the conductance of single-walled carbon nanotubes by ion irradiation in the Anderson localization regime

TL;DR

This study demonstrates how ion irradiation can precisely tune the electrical conductance of single-walled carbon nanotubes by inducing defects, primarily di-vacancies, leading to strong Anderson localization effects.

Contribution

It provides a controlled method to modify nanotube resistance via ion irradiation, linking defect density to localization phenomena with theoretical support.

Findings

Resistance increases exponentially with defect density

Di-vacancies are the main contributors to resistance increase

A small defect density causes a large resistance rise

Abstract

Carbon nanotubes are a good realization of one-dimensional crystals where basic science and potential nanodevice applications merge. Defects are known to modify the electrical resistance of carbon nanotubes. They can be present in as-grown carbon nanotubes, but controlling externally their density opens a path towards the tuning of the nanotube electronic characteristics. In this work consecutive Ar+ irradiation doses are applied to single-walled nanotubes (SWNTs) producing a uniform density of defects. After each dose, the room temperature resistance versus SWNT-length [R(L)] along the nanotube is measured. Our data show an exponential dependence of R(L) indicating that the system is within the strong Anderson localization regime. Theoretical simulations demonstrate that mainly di-vacancies contribute to the resistance increase induced by irradiation and that just a 0.03% of di-vacancies produces an increase of three orders of magnitude in the resistance of a 400 nm SWNT length.