Bandgap opening in metallic carbon nanotubes due to silicon impurities

TL;DR

This study uses density functional theory to show that silicon impurities can induce a significant bandgap in metallic carbon nanotubes, potentially enabling their use in nanoelectronic devices.

Contribution

It demonstrates that silicon adatoms can open a tunable bandgap in metallic CNTs without forming chains, a novel method for electronic property modification.

Findings

Silicon adatoms induce bandgaps between 0.10 eV and 0.47 eV.

The bandgap depends on adsorption site, Si density, and CNT chirality.

Low-density Si adatoms can open a bandgap without chain formation.

Abstract

Controlling the bandgap of carbon nanostructures is key to the development and mainstream application of carbon-based nanoelectronic devices. We report density functional theory calculations of the effect of silicon impurities on the electronic properties of carbon nanotubes (CNTs). We have found that Si adatoms open up a bandgap in intrinsically metallic CNTs even when the linear density of Si atoms is low enough that they do not create a bonded adatom chain. The bandgap opened in metallic CNTs can range between 0.10 eV and 0.47 eV, depending on adsorption site, linear density of Si adatoms, and CNT chirality.