# GW electronic structure calculations of Co doped ZnO

## TL;DR

This study uses advanced computational methods to analyze point defects in Co-doped ZnO, identifying oxygen interstitials as key to luminescence and potential ferromagnetism, advancing understanding of defect-related properties.

## Contribution

It extends previous work by using GW calculations to identify specific point defects and their electronic structures in Co-doped ZnO, highlighting oxygen interstitials as crucial.

## Key findings

- Oxygen interstitials are likely defects in Co-doped ZnO.
- Orbital analysis shows O-p and Co-d orbitals are involved.
- Defect complexes with oxygen interstitials may induce ferromagnetism.

## Abstract

Recently the point defect responsible for the intra-3$d$ luminescence of cobalt in doped ZnO samples has been indentified\,\cite{pssb2019}. In this work we further extend our investigation to other point defects in Co-doped ZnO. We use density-functional theory and GW calculations to determined the orbital-resolved band structure of cobalt doped zinc oxide (ZnO). We show that mainly O-p and Co-d orbitals take part in the process and confirm that an oxygen interstitial nearby a cobalt atom is a likely defect to occur in Co-implanted ZnO samples. We also rule out that other common point defects in ZnO can be responsible for the observed intra-3$d$ transition. Finally, we suggest that defect complexes involving oxygen interstitials could be used to promote ferromagnetism in cobalt doped ZnO samples.