mrx Materials Research Express MRX Mater. Res. Express 2053-1591 IOP Publishing mrxab8656 10.1088/2053-1591/ab8656 ab8656 MRX-120964.R2 Paper Electronic materials Thermally stimulated relaxation and behaviors of oxygen vacancies in SrTiO3 single crystals with (100), (110) and (111) orientations Thermally stimulated relaxation and behaviors of oxygen vacancies in SrTiO3 single crystals with (100), (110) and (111) orientations Qu Haimo 1 0000-0002-6762-1130 Luo Bingcheng 2 Bian Shuaishuai 1 Yue Zhenxing 1 State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, People’s Republic of China Department of Engineering, University of Cambridge, CB3 0FA Cambridge, United Kingdom yuezhx@mail.tsinghua.edu.cn

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4 2020 14 04 2020 14 04 2020 7 4 046305 26 02 2020 24 03 2020 03 04 2020 26 02 2020 © 2020 The Author(s). Published by IOP Publishing Ltd 2020 Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Abstract

The strontium titanate (SrTiO3) single crystals with different orientations of (100), (110) and (111) were investigated using thermally stimulated depolarization current (TSDC) measurements, which has been proved to be an effective strategy to fundamentally study the relationship between relaxation phenomena and defect chemistry in dielectrics. The origins of different relaxations in SrTiO3 crystals were identified and the activation energy of oxygen vacancies was estimated from TSDC measurements. It was further found that oxygen-treated SrTiO3 crystals exhibit different relaxation behaviors. Noticeable changes of thermal relaxation associated with oxygen vacancies have taken place in relation to the crystalline anisotropy. The SrTiO3 (110) samples display higher concentration and activation energy of oxygen vacancies. First-principles calculations were carried out on SrTiO3 (110) crystals to study the effect of oxygen vacancy on different surface microstructure. From the resulting minimum formation energy of 0.63 eV, it demonstrates that the oxygen vacancies tend to form on the TiO-terminated surfaces. Considering the band structure, oxygen vacancies near the surface contribute to the transition of crystal from insulator to metallic characteristic.

SrTiO3 TSDC first-principles oxygen vacancy defect relaxation National Natural Science Foundation of China https://doi.org/10.13039/501100001809 No. 51872160 National Key Research and Development Program of China No.2017YFB0406301 ccc 2053-1591/20/046305+11$33.00 crossmark yes