使用基于CMOS的scintillator检测器通过进动电子衍射辅助四维扫描透射电子显微镜（STEM）进行的自动晶体取向映射
Automated crystal orientation mapping by precession electron diffraction assisted four-dimensional scanning transmission electron microscopy (4D-STEM) using a scintillator based CMOS detector
摘要：
电子敏感和像素化探测器的最新发展吸引了四维扫描透射电子显微镜（4D-STEM）的使用。在这里，我们提出了一个进动电子衍射辅助4D-STEM技术的自动取向映射使用衍射斑点图案直接捕获的柱闪烁体的互补金属氧化物半导体（CMOS）检测器。我们比较的结果到一个传统的方法，它利用一个外部CCD摄像机拍摄的荧光屏。探测器的高动态范围和信噪比特性大大提高了衍射图案的图像质量，特别是在高散射角下衍射斑点的可见性。在通过模板匹配过程重建的方向图中，与传统方法相比，CMOS数据产生了显着减少的错误索引和更高的可靠性。也可以通过掩蔽接近直接光束的反射来提高取向差测量的角分辨率。这是因为在高散射角下取向敏感的、弱的和小的衍射斑点更显著。结果表明，精细的细节，如纳米晶粒，纳米孪晶和亚晶界可以解决与亚度角分辨率，这是可比的取向映射使用菊池衍射图案。
英文摘要：
The recent development of electron sensitive and pixelated detectors has attracted the use of four-dimensional scanning transmission electron microscopy (4D-STEM). Here, we present a precession electron diffraction assisted 4D-STEM technique for automated orientation mapping using diffraction spot patterns directly captured by an in-column scintillator based complementary metal-oxide-semiconductor (CMOS) detector. We compare the results to a conventional approach, which utilizes a fluorescent screen filmed by an external CCD camera. The high dynamic range and signal-to-noise characteristics of the detector largely improve the image quality of the diffraction patterns, especially the visibility of diffraction spots at high scattering angles. In the orientation maps reconstructed via the template matching process, the CMOS data yields a significant reduction of false indexing and higher reliability compared to the conventional approach. The angular resolution of misorientation measurement could also be improved by masking reflections close to the direct beam. This is because the orientation sensitive, weak and small diffraction spots at high scattering angle are more significant. The results show that fine details such as nanograins, nanotwins and sub-grain boundaries can be resolved with a sub-degree angular resolution which is comparable to orientation mapping using Kikuchi diffraction patterns.
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