Disordered Carbon nanotube alloys in the Effect Medium Super Cell Approximation

TL;DR

This study explores how vacancies and substitutional alloying affect the electronic properties of disordered single-walled carbon nanotubes using an effective medium super cell approximation, revealing tunable energy gaps for nanoelectronic applications.

Contribution

It introduces a detailed analysis of disorder effects in SWCNTs with vacancies and alloying, demonstrating how these alter electronic states and enable gap engineering.

Findings

Vacancies induce bound states near the Fermi level.

Increasing nitrogen or boron concentration reduces the semiconducting gap.

At a critical concentration, the gap disappears, enabling tunable electronic properties.

Abstract

We investigate a disordered single-walled carbon nanotube (SWCNT) in an effective medium super cell approximation (EMSCA). First type of disorder that we consider is the presence of vacancies. Our results show that the vacancies induce some bound states on their neighbor host sites, leading to the creation of a band around the Fermi energy in the SWCNT average density of states.Second type of disorder considered is a substitutional $B_{cb}N_{cn}C_{1-cb-cn}$ alloy due to it's applications in hetrojunctions. We found that for a fixed boron (nitrogen) concentration, by increasing the nitrogen (boron) concentration the averaged semiconducting gap, $E_{g}$, decreases and at a critical concentration it disappears. A consequence of our results for nano electronic devices is that by changing the boron(nitrogen) concentration, one can make a semiconductor SWCNT with a pre-determined energy gap.