arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1607.02640cond-mat.mtrl-sci
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环形暗场扫描透射电子显微术中单个点缺陷的选择性检测角度三维成像

Three-Dimensional Imaging of Individual Point Defects Using Selective Detection Angles in Annular Dark Field Scanning Transmission Electron Microscopy

Jared M. Johnson, Soohyun Im, Jinwoo Hwang

摘要:

我们提出了一种新的扫描透射电子显微镜(STEM)技术,可以实现三维(3D)表征的空位,较轻和较重的掺杂剂与高精度。使用多层STEM成像和β-Ga 2 O3和SrTiO 3的衍射模拟,我们表明,选择一个小范围的低散射角可以使含缺陷的原子柱的对比度基本上更依赖于深度。深度依赖性的起源是由于原子柱中存在点缺陷而导致的电子去沟道,这在低散射角下产生额外的波纹。我们表明,通过捕获的去沟道信号与窄选择的环形暗场角(例如20-40毫拉德),在图像中包含点缺陷的列的对比度可以显着增强。样品厚度,晶体取向,探头会聚角,和实验的不确定性的影响也将被讨论。因此,我们的新技术可以为功能材料中单个点缺陷的高精度3D结构表征创造新的机会。

英文摘要:

We propose a new scanning transmission electron microscopy (STEM) technique that can realize the three-dimensional (3D) characterization of vacancies, lighter and heavier dopants with high precision. Using multislice STEM imaging and diffraction simulations of beta-Ga2O3 and SrTiO3, we show that selecting a small range of low scattering angles can make the contrast of the defect-containing atomic columns substantially more depth-dependent. The origin of the depth-dependence is the de-channeling of electrons due to the existence of a point defect in the atomic column, which creates extra ripples at low scattering angles. We show that, by capturing the de-channeling signal with narrowly selected annular dark field angles (e.g. 20-40 mrad), the contrast of a column containing a point defect in the image can be significantly enhanced. The effect of sample thickness, crystal orientation, probe convergence angle, and experimental uncertainty will also be discussed. Our new technique can therefore create new opportunities for highly precise 3D structural characterization of individual point defects in functional materials.

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