The Interplay of Interstitial and Substitutional Copper in Zinc Oxide

Qing Hou; John Buckeridge; Aron Walsh; Zijuan Xie; You Lu; Thomas W Keal; Jingcheng Guan; Scott M Woodley; C Richard A Catlow; Alexey A Sokol

doi:10.3389/fchem.2021.780935

The Interplay of Interstitial and Substitutional Copper in Zinc Oxide

Front Chem. 2021 Dec 14:9:780935. doi: 10.3389/fchem.2021.780935. eCollection 2021.

Authors

Qing Hou^{1

2

3}, John Buckeridge⁴, Aron Walsh⁵, Zijuan Xie⁶, You Lu⁷, Thomas W Keal⁷, Jingcheng Guan³, Scott M Woodley³, C Richard A Catlow^{3

8}, Alexey A Sokol³

Affiliations

¹ Institute of Photonic Chips, University of Shanghai for Science and Technology, Shanghai, China.
² School of Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai, China.
³ Department of Chemistry, Kathleen Lonsdale Materials Chemistry, University College London, London, United Kingdom.
⁴ School of Engineering, London South Bank University, London, United Kingdom.
⁵ Department of Materials, Imperial College London, London, United Kingdom.
⁶ Shenzhen Institute for Quantum Science and Technology and Department of Physics, Southern University of Science and Technology, Shenzhen, China.
⁷ Scientific Computing Department, UKRI STFC Daresbury Laboratory, Warrington, United Kingdom.
⁸ School of Chemistry, Cardiff University, Cardiff, United Kingdom.

Abstract

Cu impurities are reported to have significant effects on the electrical and optical properties of bulk ZnO. In this work, we study the defect properties of Cu in ZnO using hybrid quantum mechanical/molecular mechanical (QM/MM)-embedded cluster calculations based on a multi-region approach that allows us to model defects at the true dilute limit, with polarization effects described in an accurate and consistent manner. We compute the electronic structure, energetics, and geometries of Cu impurities, including substitutional and interstitial configurations, and analyze their effects on the electronic structure. Under ambient conditions, Cu_Zn is the dominant defect in the d⁹ state and remains electronically passive. We find that, however, as we approach typical vacuum conditions, the interstitial Cu defect becomes significant and can act as an electron trap.

Keywords: copper; defects; dopant; hybrid QM/MM; zinc oxide.