Strain-tunable direct band gap of ZnO monolayer in graphene-like honeycomb structure

TL;DR

This study demonstrates that applying biaxial strain to ZnO monolayers with a graphene-like structure can effectively tune their direct band gap, which is promising for nano-electromechanical and optomechanical applications.

Contribution

The paper introduces the first computational demonstration of strain-tunable direct band gap in monolayer ZnO with a graphene-like honeycomb structure.

Findings

Unstrained ML-ZnO has a direct band gap of 1.68 eV.

The band gap remains direct under ±10% strain.

Band gap varies non-linearly with applied strain.

Abstract

Using full-potential density functional calculations within local density approximation (LDA), we found mechanically tunable band-gap in ZnO monolayer (ML-ZnO) in graphene-like honeycomb structure, by simulated application of in-plane homogeneous biaxial strain. Unstrained ML-ZnO was found to have a direct band gap of energy 1.68 eV within LDA; the actual band gap would be more, since LDA is known to underestimate the gap. Within our simulated strain limit of about plus or minus 10%, the band gap remains direct and shows a strong non-linear variation with strain. The results may find applications in future nano-electromechanical systems (NEMS) and nano-optomechanial systems (NOMS).