Theoretical study of precision and accuracy of strain analysis by nano-beam electron diffraction
Theoretical study of precision and accuracy of strain analysis by nano-beam electron diffraction
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DOI：
10.1016/j.ultramic.2015.06.011
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发表时间：
2015-11-01
期刊：
影响因子：
2.2
通讯作者：
Rosenauer, Andreas
中科院分区：
文献类型：
--
作者：
Mahr, Christoph;Mueller-Caspary, Knut;Rosenauer, Andreas
晶格应变的测量是表征半导体纳米结构的重要手段。由于应变对电子能带结构的影响很大，高精度、高精度、大视场空间分辨率的应变测量方法势在必行。本文对纳束会聚电子衍射法测量应变的精密度和准确度进行了理论研究。结果表明，在聚焦电子束覆盖的区域内，由于应变的变化而引起的衍射图中的光晕，影响了评价的准确性。这种效应在不同晶格面距离的材料之间的尖锐界面上预计会很强，将讨论使用常规探针的会聚束电子衍射图案和由进动电子束形成的图案。此外，我们还讨论了优化界面应变测量精度的方法。这项研究是基于对不同现实结构模拟的衍射图的评估，这些衍射图已经在以前的出版物中进行了实验研究。这些模拟使用冻结格子方法和图像记录系统的调制传递函数来考虑热扩散散射。此外，还研究了泊松噪声的影响。(C)2015爱思唯尔B.V.保留所有权利
Measurement of lattice strain is important to characterize semiconductor nanostructures. As strain has large influence on the electronic band structure, methods for the measurement of strain with high precision, accuracy and spatial resolution in a large field of view are mandatory. In this paper we present a theoretical study of precision and accuracy of measurement of strain by convergent nano-beam electron diffraction. It is found that the accuracy of the evaluation suffers from halos in the diffraction pattern caused by a variation of strain within the area covered by the focussed electron beam. This effect, which is expected to be strong at sharp interfaces between materials with different lattice plane distances, will be discussed for convergent beam electron diffraction patterns using a conventional probe and for patterns formed by a precessing electron beam. Furthermore, we discuss approaches to optimize the accuracy of strain measured at interfaces. The study is based on the evaluation of diffraction patterns simulated for different realistic structures that have been investigated experimentally in former publications. These simulations account for thermal diffuse scattering using the frozen lattice approach and the modulation transfer function of the image recording system. The influence of Poisson noise is also investigated. (C) 2015 Elsevier B.V. All rights reserved