Zn vacancy as a polaronic hole trap in ZnO

Y. K. Frodason, K. M. Johansen, T. S. Bjørheim, B. G. Svensson, and A. Alkauskas
Phys. Rev. B 95, 094105 – Published 10 March 2017

Abstract

This work explores the Zn vacancy in ZnO using hybrid density functional theory calculations. The Zn vacancy is predicted to be an exceedingly deep polaronic acceptor that can bind a localized hole on each of the four nearest-neighbor O ions. The hole localization is accompanied by a distinct outward relaxation of the O ions, which leads to lower symmetry and reduced formation energy. Notably, we find that initial symmetry breaking is required to capture this effect. We present a simple model to rationalize our findings with regard to the approximately equidistant thermodynamic charge-state transition levels. Furthermore, by employing a one-dimensional configuration coordinate model with parameters obtained from the hybrid density functional theory calculations, luminescence line shapes were calculated. The results show that the isolated Zn vacancy is unlikely to be the origin of the commonly observed luminescence in the visible part of the emission spectrum from n-type material, but rather the luminescence in the infrared region.

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  • Received 16 December 2016
  • Revised 15 February 2017

DOI:https://doi.org/10.1103/PhysRevB.95.094105

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Y. K. Frodason*, K. M. Johansen, T. S. Bjørheim, and B. G. Svensson

  • Centre for Materials Science and Nanotechnology, University of Oslo, N-0318 Oslo, Norway

A. Alkauskas

  • Center for Physical Sciences and Technology, LT-10257 Vilnius, Lithuania

  • *ymirkf@fys.uio.no

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Issue

Vol. 95, Iss. 9 — 1 March 2017

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