Gao, D;
Strand, J;
Munde, M;
Shluger, A;
(2019)
Mechanisms of Oxygen Vacancy Aggregation in SiO2 and HfO2.
Frontiers in Physics
, 7
, Article 43. 10.3389/fphy.2019.00043.
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Abstract
Dielectric oxide films in electronic devices undergo significant structural changes during device operation under bias. These changes are usually attributed to aggregation of oxygen vacancies resulting in formation of oxygen depleted regions and conductive filaments. However, neutral oxygen vacancies have high diffusion barriers in ionic oxides and their interaction and propensity for aggregation are still poorly understood. In this paper we briefly review the existing data on static configurations of neutral dimers and trimers of oxygen vacancies in technologically relevant SiO2 and HfO2 and then provide new results on the structure and properties of these defects in amorphous SiO2 and HfO2. These results demonstrate weak interaction between neutral O vacancies, which does not explain their quick aggregation. We propose that trapping of electrons, injected from an electrode, by the vacancies may result in creation of new neutral vacancies in the vicinity of pre-existing vacancies. We describe this mechanism in aSiO2 and demonstrate that this process becomes more efficient as the vacancy clusters grow larger.
| Type: | Article |
|---|---|
| Title: | Mechanisms of Oxygen Vacancy Aggregation in SiO2 and HfO2 |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3389/fphy.2019.00043 |
| Publisher version: | https://doi.org/10.3389/fphy.2019.00043 |
| Language: | English |
| Additional information: | This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms https://creativecommons.org/licenses/by/4.0/ |
| Keywords: | dielectric oxides, oxygen vacancies, Density Functional Theory, SiO2, HfO |
| 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/10076461 |
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