Regulation of oxygen vacancy types on SnO2 (110) surface by external strain

TL;DR

This study uses first-principle calculations to show how external strain can control the type and formation energy of oxygen vacancies on SnO2 (110) surfaces, impacting their optical properties.

Contribution

It demonstrates that external strain can be used to regulate oxygen vacancy types and formation energies on SnO2 surfaces, providing a new approach for material property tuning.

Findings

External strain alters oxygen vacancy formation energy and preferred sites.

Compressive strain shifts vacancy preference from bridging to plane sites.

Strain-induced electronic redistribution enables vacancy control.

Abstract

In tin dioxide nanostructures, oxygen vacancies (OVs) play an important role in their optical properties and thus regulation of both OV concentration and type via external strain is crucial to exploration of more applications. First-principle calculations of SnO2 (110) surface disclose that asymmetric deformations induced by external strain not only lead to its intrinsic surface elastic changes, but also result in different OV formation energy. In the absence of external strain, the energetically favorable oxygen vacancies (EFOV) appear in the bridging site of second layer. When -3.5% external strain is applied along y direction, the EFOV moves into plane site. This can be ascribed that the compressed deformation gives rise to redistribution of electronic wave function near OVs, therefore, formation of newly bond structures. Our results suggest that different type OVs in SnO2 surface can be controlled by strain engineering.