Measurement of the chemical composition of nanostructures by quantification of Z-contrast in scanning-transmission electron microscopy

通过扫描透射电子显微镜中 Z 对比度的量化来测量纳米结构的化学成分

• 批准号: 134655250
• 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: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/134655250?language=en
• 关键词: Measurement; chemical; composition; nanostructures; quantification

In project we developed a method to precisely analyse the chemical composition in a sample using scanning-transmission electron microscopy (STEM). The method wich is based on a direct comparsion of the experimental high-angle annular dark field (HAADF) intensity with simulations was already applied to many different materials.So far, the intensity was measured by integrating the scattered intensity over a certain angular range which is defined by the camera length and the geometry of the detector. In this renewal proposal we aim at a measurement of STEM intensity as a function of the scattering angle. The angle-dependence of the scattered intensity is not only influenced by the chemical concentration but also by the type of the scattering process (e.g. thermal-diffuse scattering or scattering at static atomic displacements) and by distortions of the crystal lattice. Therefore, the scattering intensity measured with selected detection angles contains additional information which allows for measuring two or more experimental parameters (e.g. thickness and chemical concentration) at the same time. For this purpose we suggest to install a motor-driven diaphragm directly above the HAADF detector in the microscope.The new method will be able to measure the local chemical concentration of a single element (e.g. In in InGaN) and the local specimen thickness or the local chemical concentrations of two elements (e.g. In and Al in InAlGaN) at the same time. Our priliminary studies using a prototype diaphragm show that our method allows for either making strain fields visible or performing quantitative chemical analyses without strain-induced artifacts. The studies further show a difference in the angle-dependend intensity distribution between experiment and simulation at angles smaller than 40 mrad. A main topic of this proposal is the quantification of the small-angle scattering intensity, which includes the investigation of plasmon scattering and its implementation into our simulation software using different apporaches.The method will contribute to various cooperations and projects by its application to investigate quantum dots, quaternary layers, segregation effects, nano particles of non-homogeneous composition, nano-pourous gold and SiGe MOSFETs. Thus, the project will significantly contribute to the understanding of semiconductor nanostructures and catalysists by the suggested method.

在项目中，我们开发了一种使用扫描传输电子显微镜（STEM）精确分析样品中化学成分的方法。该方法基于实验高角环形暗场（HAADF）强度与模拟的直接相匹配已应用于许多不同的材料。在此更新建议中，我们旨在测量茎强度随散射角的函数。散射强度的角度依赖性不仅受化学浓度的影响，而且还受散射过程的类型（例如，在静态原子位移处的热散射散射或散射）和晶体晶格的扭曲。因此，用选定检测角度测量的散射强度包含其他信息，可以同时测量两个或多个实验参数（例如厚度和化学浓度）。 For this purpose we suggest to install a motor-driven diaphragm directly above the HAADF detector in the microscope.The new method will be able to measure the local chemical concentration of a single element (e.g. In in InGaN) and the local specimen thickness or the local chemical concentrations of two elements (e.g. In and Al in InAlGaN) at the same time.我们使用原型隔膜的预先研究表明，我们的方法允许使应变场可见或进行定量化学分析，而无需应变诱导的伪影。研究进一步表明，在小于40 mrad的角度，实验与模拟之间的角度依赖性强度分布有所不同。该提案的一个主要主题是对小角度散射强度的量化，其中包括使用不同的附属物对等离子体散射及其在我们的仿真软件中的实现。该方法将通过其应用于调查量子点，Quaternary层，Quaternary层，分离效应的量子点，非跨跨摩托元素的粒子和SASFOUS，NANO-POUROUS，NANONANO-nano nano-nano-nano nano nano-nano-nano nano-nano-nano nano-nano nano nano nano nano nano nano nano nano nano nano nano nano nano nano nano nano nano nano nano nano。因此，通过建议的方法，该项目将显着有助于理解半导体纳米结构和催化剂。

项目成果

Angle-resolved STEM using an iris aperture: Scattering contributions and sources of error for the quantitative analysis in Si.

使用虹膜孔径的角度分辨 STEM：Si 定量分析的散射贡献和误差源

• DOI: 10.1016/j.ultramic.2020.113175
• 发表时间: 2021
• 期刊: Ultramicroscopy
• 影响因子: 2.2
• 作者: Tim Grieb;Florian F. Krause;Knut Müller-Caspary;Saleh Firoozabadi;Christoph MahrMarco Schowalter;Andreas Beyer;Oliver Oppermann;Kerstin Volz;Andreas Rosenauer
• 通讯作者: Andreas Rosenauer