Ishikawa Ryo, Tanaka Riku, Kawahara Kazuaki, Shibata Naoya, Ikuhara Yuichi
Institute of Engineering Innovation, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
ACS Nano. 2021 May 25;15(5):9186-9193. doi: 10.1021/acsnano.1c02907. Epub 2021 May 13.
The surface of metal oxides is of technological importance and is extensively used as a substrate for various electronic and chemical applications. A real surface, however, is not a perfectly well-defined and clean surface, but rather contains a diverse class of atomistic defects. Here, we show the direct determination of the 3D surface atomic structure of SrTiO (001) including termination layers and atomistic defects such as vacancies, adatoms, ledges, kinks, and their complex combinations, by using depth sectioning of atomic-resolution annular dark-field scanning transmission electron microscopy (ADF STEM). To overcome the poor depth resolution in STEM, we statistically analyze the column by column depth profiles of ADF STEM images with a Bayesian framework fitting algorithm, and we achieve depth resolution at the entrance surface of ±0.9 Å for 1518 individual atomic columns. The present atomic-resolution 3D electron microscopy at the surface will provide fertile ground especially in surface science.
金属氧化物表面具有重要的技术意义，被广泛用作各种电子和化学应用的基底。然而，真实的表面并非完美定义且干净的表面，而是包含各种各样的原子缺陷。在此，我们展示了通过原子分辨率环形暗场扫描透射电子显微镜（ADF STEM）的深度切片，直接确定SrTiO(001)的三维表面原子结构，包括终止层和诸如空位、吸附原子、台阶、扭结及其复杂组合等原子缺陷。为了克服STEM中较差的深度分辨率，我们使用贝叶斯框架拟合算法对ADF STEM图像逐列深度分布进行统计分析，在1518个单独的原子列中，在入射表面实现了±0.9 Å的深度分辨率。目前表面的原子分辨率三维电子显微镜将为特别是表面科学提供丰富的研究基础。
