El-Sayed, A;
Watkins, MB;
Grasser, T;
Shluger, AL;
(2018)
Effect of electric field on migration of defects in oxides: Vacancies and interstitials in bulk MgO.
Physical Review B
, 98
(6)
, Article 064102. 10.1103/PhysRevB.98.064102.
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Abstract
Dielectric layers composed of metal oxides are routinely subjected to external electric fields during the course of normal operation of electronic devices. Many phenomenological theories suggest that electric fields strongly affect the properties and mobilities of defects in oxide films and can even facilitate the creation of new defects. Although defects in metal oxides have been studied extensively both experimentally and theoretically, the effect of applied electric fields on their structure and migration barriers is not well understood and still remains subject to speculations. Here, we investigate how static, homogeneous electric fields affect migration barriers of canonical defects—oxygen vacancies and interstitial ions—in a prototypical oxide, MgO. Using the modern theory of polarization within density functional theory (DFT), we apply electric fields to defect migration pathways in three different charge states. The effect of the field is characterized by the change of the dipole moment of the system along the migration pathway. The largest changes in the calculated barriers are observed for charged defects, while those for the neutral defects are barely significant. We show that by multiplying the dipole moment difference between the initial and the transition states, which we define as the effective dipole moment, by the field strength, one can obtain an estimate of the barrier change in excellent agreement with the DFT calculated values. These results will help to assess the applicability of phenomenological models and elucidate linear and nonlinear effects of field application in degradation of microelectronic devices, electrocatalysis, batteries, and other applications.
| Type: | Article |
|---|---|
| Title: | Effect of electric field on migration of defects in oxides: Vacancies and interstitials in bulk MgO |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1103/PhysRevB.98.064102 |
| Publisher version: | https://doi.org/10.1103/PhysRevB.98.064102 |
| Language: | English |
| Additional information: | Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/). Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10063705 |
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