Dislocations as natural quantum wires in Diamond

TL;DR

This study reveals that dislocations in diamond can act as natural quantum wires with distinct electronic properties, depending on their atomic structure, potentially enabling new nanoelectronic and optical applications.

Contribution

It demonstrates, through first-principles calculations, that dislocation cores in diamond form 1D electronic states with metallic or semiconducting behavior based on their structure.

Findings

Mixed dislocations exhibit 1D metallic bands with a characteristic density of states.

Reconstructed dislocation cores lose their metallic band, becoming semiconducting.

Pure edge dislocations show a 1D semiconductor with a 3.0 eV band gap.

Abstract

We study the electronic properties of the glide set of dislocations in diamond from first principles using hybrid exchange correlation functionals and find that the atomic-scale dislocation core states give rise to a prototypical one-dimensional (1D) band structure, i.e. natural quantum wires. The position and character of the core states varies strongly with local structure, where mixed dislocations with dangling bonds exhibit a 1D metallic band with a characteristic 1D density of states ($1/\sqrt{E})$. This 1D Fermi gas is spatially localized to single atomic diameter orbital chain along the dislocation core. When the dangling bonds within the core are reconstructed, the 1D metallic band disappears. In contrast, pure edge dislocations in diamond reveal a 1D semiconductor with a direct band gap of 3.0 eV. These calculations provide a possible explanation to the long standing observation of a blue luminescence band correlated with dislocations in diamond. This opens the door to using dislocations as 1D quantum phases with functional (electronic and optical) properties arising from the atomic-scale core states.