Identification of a functional point defect in SrTiO3
Identification of a functional point defect in SrTiO3
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DOI：
10.1103/physrevmaterials.2.060403
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发表时间：
2018-06-21
影响因子：
3.4
通讯作者：
Eom, Chang-Beom
中科院分区：
文献类型：
--
作者：
Lee, Daesu;Wang, Hongwei;Eom, Chang-Beom
揭示点缺陷的存在和性质是凝聚态物理和材料科学中最大的挑战之一。特别是在复杂氧化物中，即使是微量的不可避免的点缺陷也可以产生新的物理现象和功能，例如可见光发射和铁电性，但仍然难以清楚地识别这些点缺陷。在这里，以SrTiO 3作为模型系统，我们表明，原子层和化学计量控制的薄膜外延，混合密度泛函理论和高分辨率阴极射线发光光谱之间的迭代反馈允许识别的功能阳离子缺陷，钛反位（Ti-Sr）缺陷。我们的阴极发光测量揭示了子带隙发光，其光谱精细结构表现出良好的定量协议，以及一对一的对应关系，与理论预测的光学跃迁从本征点缺陷，如Ti-Sr的理论和光谱结果的指导下，我们还控制阳离子的化学计量，它反过来又导致在阴极发光光谱的良好系统性。不限于钛-锶的识别，这种方法允许更可靠的，自洽的缺陷研究，并提供了关键的洞察复杂氧化物中的点缺陷的微观图片。
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 (Ti-Sr) 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 Ti-Sr. 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 Ti-Sr, this approach allows for more reliable, self-consistent defect study, and provides critical insight into amicroscopic picture of point defects in complex oxides.