Enhancement of resolution and precision of TEM imaging by scanning illumination

通过扫描照明提高 TEM 成像的分辨率和精度

• 批准号: 392948259
• 负责人: Professor Dr. Andreas Rosenauer
• 金额: --
• 依托单位: Institut für Festkörperphysik (IFP)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/392948259?language=en
• 关键词: Enhancement; resolution; precision; TEM; imaging

In transmission electron microscopy (TEM), mainly two imaging modes are differentiated: Conventional TEM (CTEM), which uses a plane coherent electron wave to illuminate the specimen, and scanning TEM (STEM), where the electron beam is scanned over the specimen and scattered electrons are registered by a detector. CTEM has the advantage of direct imaging which is not influenced by errors of positioning the electron beam. In contrast, as STEM is an incoherent imaging mode, the interpretation of images is easier and it provides a better spatial resolution.We were able to demonstrate in an article published in Phys. Rev. Lett. by experiment and simulation that the new imaging mode ISTEM (imaging STEM), which applies scanning illumination in the CTEM imaging mode, combines advantages of CTEM and STEM. It provides better spatial resolution than CTEM, interpretation of contrast patterns is easier and there is no influence of errors in positioning the electron beam. However, the advantages of ISTEM are accompanied by the disadvantage of a more difficult practicability. A first goal of the project is to improve the applicability of ISTEM by writing dedicated scripts to operate and adjust the microscope as well as reducing the contamination of the sample. In addition, advantages of ISTEM imaging that have only been shown by simulation so far will be demonstrated experimentally. These advantages include the higher precision of measuring the positions of atom columns, as well as the outstanding possibilities to image light atom columns in direct vicinity of heavy atom columns. In a recent publication of Prof. L. Allen et al. in Australia it was suggested to apply ISTEM for elemental analysis by energy filtered imaging with reduced artifacts. This approach will be tested in cooperation with the ER-C Jülich.The advantages of ISTEM imaging will be demonstrated using technologically relevant material systems that are connected with highly topical problems. The improved precision of the measurement of atom column positions will be applied to measure polarization domains in only a few nanometers thick ferroelectric tunnel barriers which are potential candidates for application in memory devices. Particularly, we plan to investigate the switching behavior of these barriers using in-situ applied electric fields. In addition, the possibilities of ISTEM to image light atom columns will be applied to measure tilts of oxygen-octahedra across the interfaces between different perovskite materials. Further applications are the measurement of spontaneous wrinkling of lattice planes in Te nanowires which can be applied in NO2 sensors, as well as the investigation of lattice strain close to the surface of nanoporous gold, which influences the catalytic activity of this material system.

在透射电子显微镜（TEM）中，主要两种成像模式是区别的：常规TEM（CTEM），该模式使用平面相干电子波照明样品，并扫描TEM（stem），在该样品上扫描了电子束在样品上扫描和散射的电子，并由检测器注册。 CTEM具有直接成像的优点，该成像不受定位电子束的误差的影响。相比之下，由于STEM是一种不一致的成像模式，因此图像的解释更加容易，并且提供了更好的空间分辨率。我们能够在Phys发表的文章中证明。莱特牧师。通过实验和模拟，在CTEM成像模式下应用扫描照明的新成像模式ISTEM（成像型）结合了CTEM和STEM的优势。它提供了比CTEM更好的空间分辨率，对比模式的解释更容易，并且在定位电子束时没有错误的影响。但是，ISTEM的优势伴随着更加困难的实践性的灾难。该项目的第一个目标是通过编写专用脚本来操作和调整显微镜以及减少样本的污染来提高ISTEM的适用性。另外，仅通过模拟显示的ISTEM成像的优势将在实验中证明。这些优点包括测量原子柱位置的更高精度，以及在重原子柱直接附近图像光原子柱的出色可能性。在L. Allen等人的最新出版物中。在澳大利亚，建议通过减少伪像的能量过滤成像来应用ISTEM进行元素分析。该方法将与ER-CJülich合作测试。ISTEM成像的优势将使用与高度局部问题相关的技术相关材料系统来证明。在仅几种纳米厚的铁电隧道屏障中，原子柱位置测量的提高精度将应用于测量极化域，这是在存储器设备中使用的潜在候选物。特别是，我们计划使用原位施加的电场研究这些障碍的切换行为。另外，ISTEM到图像光原子柱的可能性将应用于在不同的钙钛矿材料之间的界面上测量氧气 - octahedra的倾斜度。进一步的应用是测量可以在NO2传感器中应用的纳米线中晶格平面的发起人自发包装，以及靠近纳米孔金表面的晶格菌株的投资，这影响了该材料系统的催化活性。