Unveiling both the presence and nature of point defects is one of the biggest challenges in condensed matter physics and materials science. Particularly in complex oxides, even a minute amount of unavoidable point defects could generate novel physical phenomena and functions, such as visible light emission and ferroelectricity, yet it remains elusive to clearly identify such point defects. Here, taking SrTiO3 as a model system, we show that iterative feedback among atomic-layer- and stoichiometry-controlled thin-film epitaxy, hybrid density functional theory, and high-resolution cathodoluminescence spectroscopy allows for the identification of a functional cationic defect, the Ti antisite (TiSr) defect. Our cathodoluminescence measurements reveal sub-band-gap luminescence, whose spectral fine structures show excellent quantitative agreement, as well as a one-to-one correspondence, with the theoretically predicted optical transitions from intrinsic point defects such as TiSr. Guided by the theory and spectroscopic results, we also control a cation stoichiometry, and it in turn results in good systematics in cathodoluminescence spectra. Not limited to the identification of TiSr, this approach allows for more reliable, self-consistent defect study, and provides critical insight into a microscopic picture of point defects in complex oxides.
Lee, Daesu, et al. "Identification of a functional point defect in <math><mrow><mi>SrTi</mi><msub><mi mathvariant='normal'>O</mi><mn>3</mn></msub></mrow></math>." Physical Review Materials, vol. 2, no. 6, Jun. 2018. https://doi.org/10.1103/PhysRevMaterials.2.060403
Lee, Daesu, Wang, Hongwei, Noesges, Brenton A., et al., "Identification of a functional point defect in <math><mrow><mi>SrTi</mi><msub><mi mathvariant='normal'>O</mi><mn>3</mn></msub></mrow></math>," Physical Review Materials 2, no. 6 (2018), https://doi.org/10.1103/PhysRevMaterials.2.060403
@article{osti_1529124,
author = {Lee, Daesu and Wang, Hongwei and Noesges, Brenton A. and Asel, Thaddeus J. and Pan, Jinbo and Lee, Jung-Woo and Yan, Qimin and Brillson, Leonard J. and Wu, Xifan and Eom, Chang-Beom},
title = {Identification of a functional point defect in <math><mrow><mi>SrTi</mi><msub><mi mathvariant='normal'>O</mi><mn>3</mn></msub></mrow></math>},
annote = {Unveiling both the presence and nature of point defects is one of the biggest challenges in condensed matter physics and materials science. Particularly in complex oxides, even a minute amount of unavoidable point defects could generate novel physical phenomena and functions, such as visible light emission and ferroelectricity, yet it remains elusive to clearly identify such point defects. Here, taking SrTiO3 as a model system, we show that iterative feedback among atomic-layer- and stoichiometry-controlled thin-film epitaxy, hybrid density functional theory, and high-resolution cathodoluminescence spectroscopy allows for the identification of a functional cationic defect, the Ti antisite (TiSr) defect. Our cathodoluminescence measurements reveal sub-band-gap luminescence, whose spectral fine structures show excellent quantitative agreement, as well as a one-to-one correspondence, with the theoretically predicted optical transitions from intrinsic point defects such as TiSr. Guided by the theory and spectroscopic results, we also control a cation stoichiometry, and it in turn results in good systematics in cathodoluminescence spectra. Not limited to the identification of TiSr, this approach allows for more reliable, self-consistent defect study, and provides critical insight into a microscopic picture of point defects in complex oxides.},
doi = {10.1103/PhysRevMaterials.2.060403},
url = {https://www.osti.gov/biblio/1529124},
journal = {Physical Review Materials},
issn = {ISSN 2475-9953},
number = {6},
volume = {2},
place = {United States},
year = {2018},
month = {06}}