AUTHOR=Hou Qing , Buckeridge John , Walsh Aron , Xie Zijuan , Lu You , Keal Thomas W. , Guan Jingcheng , Woodley Scott M. , Catlow C. Richard A. , Sokol Alexey A. TITLE=The Interplay of Interstitial and Substitutional Copper in Zinc Oxide JOURNAL=Frontiers in Chemistry VOLUME=9 YEAR=2021 URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2021.780935 DOI=10.3389/fchem.2021.780935 ISSN=2296-2646 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, CuZn 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.