Spatial resolution of strain state analysis by convergent nano beam electron diffraction

会聚纳米束电子衍射应变状态分析的空间分辨率

• 批准号: 266456134
• 负责人: Professor Dr. Andreas Rosenauer
• 金额: --
• 依托单位: Centre CEA de Grenoble
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/266456134?language=en
• 关键词: Spatial; resolution; strain; state; analysis

Development of methods for measurement of strain with sub-nanometer spatial resolution is of high relevance for material science as well as industrial microelectronics production. Local strain fields influence mechanic and electronic properties of semiconductor nanostructures and govern kinetic processes of epitaxial growth. For convergent nano-beam electron diffraction the specimen surface is scanned with a focused electron beam whose diameter lies in the sub-nanometer range. This leads to formation of diffraction disks in the back focal plane of the objective lens. The distance of a diffracted disk from the undiffracted one depends on the local lattice parameter and thus is given by the local lattice strain. Using this principle, the authors of this proposal developed and published the SANBED (strain analysis by nano beam electron diffraction) method for strain state analysis, which uses an electron beam with 0.5-0.7 nm width. This method yields a very high precision which is comparable with the best values published in literature using transmission electron microscopy. However, analysing a semiconductor nanostructure close to an interface, it is possible that a part of the tail of the electron beam extends beyond the interface. Although this part of the electron beam has a small local intensity, this effect reduces the spatial resolution of strain measurement in a complex manner. Aim of this proposal is measurement and optimisation of the spatial resolution of the strain analysis with the SANBED method. It is planned to use three semiconductor nanostructure samples with published well-known composition profiles as reference samples to measure strain profiles with the published standard-SANBED method. Then, the experimental results will be compared with image simulation. To this end, various approximations with different complexity will be tested, aiming at high accuracy at sufficiently small computation time. In the second part of the project we will investigate improvement of the spatial resolution of the method by optimizing the experimental parameters as well as the evaluation method. Experimental parameters include selection and excitation of different reflections and the geometry of the condenser aperture. Concerning the evaluation procedure we intend to test additional filtering and alternative methods to measure positions of diffraction disks. To perform the optimizations in an efficient way, both experimental measurement and image simulation will be applied. In the third part of the project the beam semi convergence angle will be increased so that the diffraction disks start to overlap, which leads to a smaller diameter of the illuminating electron beam. We expect that this also improves the spatial resolution of the strain evaluation. On the other hand, the method for measurement of disk position must be adapted so that it can be applied to overlapping diffraction disks.

发展亚纳米空间分辨率的应变测量方法对于材料科学以及工业微电子生产具有高度相关性。局域应变场影响半导体纳米结构的力学和电学性质，并控制外延生长的动力学过程。对于会聚纳米束电子衍射，样品表面用直径在亚纳米范围内的聚焦电子束扫描。这导致在物镜透镜的后焦平面中形成衍射盘。衍射圆盘与未衍射圆盘的距离取决于局部晶格参数，因此由局部晶格应变给出。利用这一原理，该提案的作者开发并发表了用于应变状态分析的SANBED（纳米束电子衍射应变分析）方法，该方法使用宽度为0.5-0.7 nm的电子束。这种方法产生了一个非常高的精度，这是与最好的值发表在文献中使用透射电子显微镜。然而，分析靠近界面的半导体纳米结构，电子束尾部的一部分可能延伸超出界面。虽然这部分电子束具有小的局部强度，但这种效应以复杂的方式降低了应变测量的空间分辨率。该提案的目的是测量和优化SANBED方法应变分析的空间分辨率。计划使用三个具有已公布的众所周知的组成分布的半导体纳米结构样品作为参考样品，以使用已公布的标准-SANBED方法测量应变分布。然后，将实验结果与图像模拟进行比较。为此，将测试具有不同复杂性的各种近似值，目的是在足够小的计算时间内获得高精度。在项目的第二部分中，我们将研究通过优化实验参数以及评估方法来提高该方法的空间分辨率。实验参数包括不同反射的选择和激发以及聚光器孔径的几何形状。关于评估程序，我们打算测试额外的过滤和替代方法来测量衍射盘的位置。为了以有效的方式进行优化，将应用实验测量和图像模拟。在项目的第三部分中，电子束半会聚角将增加，使得衍射盘开始重叠，这导致照射电子束的直径更小。我们预计这也会提高应变评估的空间分辨率。另一方面，必须调整用于测量盘位置的方法，使得其可以应用于重叠衍射盘。

项目成果

Strain analysis from nano-beam electron diffraction: Influence of specimen tilt and beam convergence.

纳米束电子衍射应变分析：样品倾斜和光束会聚的影响

• DOI: 10.1016/j.ultramic.2018.03.013
• 发表时间: 2018
• 期刊: Ultramicroscopy
• 影响因子: 2.2
• 作者: T. Grieb;F. F. Krause;M. Schowalter;D. Zillmann;R. Sellin;K. Müller-Caspary;C. Mahr;T. Mehrtens;D. Bimberg;A. Rosenauer
• 通讯作者: A. Rosenauer

Measurement of local crystal lattice strain variations in dealloyed nanoporous gold

• DOI: 10.1080/21663831.2017.1396263
• 发表时间: 2018-01-01
• 期刊: MATERIALS RESEARCH LETTERS
• 影响因子: 8.3
• 作者: Mahr, Christoph;Mueller-Caspary, Knut;Rosenauer, Andreas
• 通讯作者: Rosenauer, Andreas