Müller E, Gerthsen D
Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT), Engesserstr. 7, 76131 Karlsruhe, Germany.
Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT), Engesserstr. 7, 76131 Karlsruhe, Germany.
Ultramicroscopy. 2017 Feb;173:71-75. doi: 10.1016/j.ultramic.2016.12.003. Epub 2016 Dec 3.
The contrast of backscattered electron (BSE) images in scanning electron microscopy (SEM) depends on material parameters which can be exploited for composition quantification if some information on the material system is available. As an example, the In-concentration in thin InGaAs layers embedded in a GaAs matrix is analyzed in this work. The spatial resolution of the technique is improved by using thin electron-transparent specimens instead of bulk samples. Although the BSEs are detected in a comparably small angular range by an annular semiconductor detector, the image intensity can be evaluated to determine the composition and local thickness of the specimen. The measured intensities are calibrated within one single image to eliminate the influence of the detection and amplification system. Quantification is performed by comparison of experimental and calculated data. Instead of using time-consuming Monte-Carlo simulations, an analytical model is applied for BSE-intensity calculations which considers single electron scattering and electron diffusion.
扫描电子显微镜（SEM）中背散射电子（BSE）图像的对比度取决于材料参数，如果已知材料系统的一些信息，这些参数可用于成分定量分析。例如，本工作分析了嵌入砷化镓（GaAs）基体中的薄铟镓砷（InGaAs）层中的铟浓度。通过使用薄的电子透明样品而非块状样品，提高了该技术的空间分辨率。尽管背散射电子由环形半导体探测器在相对较小的角度范围内进行检测，但可以通过评估图像强度来确定样品的成分和局部厚度。在单个图像内对测量强度进行校准，以消除检测和放大系统的影响。通过比较实验数据和计算数据进行定量分析。本研究没有使用耗时的蒙特卡罗模拟，而是应用了一个考虑单电子散射和电子扩散的解析模型来计算背散射电子强度。
