Electronic states of metallic and semiconducting carbon nanotubes with bond and site disorder

TL;DR

This paper investigates how bond and site disorder affect the electronic density of states in metallic and semiconducting carbon nanotubes, revealing disorder-induced states at the Fermi level with implications for experiments.

Contribution

It provides a comparative analysis of bond and site disorder effects on the density of states in different types of carbon nanotubes using a tight binding model.

Findings

Disorder causes the merging of conduction and valence bands at strong disorder.

Finite density of states appears at the Fermi energy due to disorder.

Bond disorder leads to a significantly higher density of states at the Fermi level.

Abstract

Disorder effects on the density of states in carbon nanotubes are analyzed by a tight binding model with Gaussian bond or site disorder. Metallic armchair and semiconducting zigzag nanotubes are investigated. In the strong disorder limit, the conduction and valence band states merge, and a finite density of states appears at the Fermi energy in both of metallic and semiconducting carbon nanotubes. The bond disorder gives rise to a huge density of states at the Fermi energy differently from that of the site disorder case. Consequences for experiments are discussed.