Walther T
Center of Advanced European Studies and Research (caesar), Electron Microscopy Group, Ludwig-Erhard-Allee 2, D-53175 Bonn, Germany.
J Microsc. 2006 Feb;221(Pt 2):137-44. doi: 10.1111/j.1365-2818.2006.01551.x.
A new procedure to quantify the contrast in annular dark field images recorded without lattice resolution in a scanning transmission electron microscope is proposed. The method relies on the use of an in-column energy filter prior to the annular dark field detector and the acquisition of a series of energy-filtered images as a function of the inner detection angle. When the image contrast of an interface between two materials in such energy-filtered annular dark field images is plotted vs. camera length and extrapolated to zero (i.e. infinite scattering angle), the contrast is shown to behave exactly as predicted by Rutherford's scattering formula (i.e. intensity scales proportional, variantZ2). This can then be used to determine the local chemistry at and the effective chemical widths of interfaces or thin films without any additional spectroscopy method for calibration, provided the global chemical composition is known. As examples, the systems SiGe/Si and InGaAs/Ge are considered in detail.
提出了一种新的程序，用于量化在扫描透射电子显微镜中无晶格分辨率记录的环形暗场图像中的对比度。该方法依赖于在环形暗场探测器之前使用柱内能量过滤器，并获取一系列作为内检测角度函数的能量过滤图像。当将这种能量过滤环形暗场图像中两种材料之间界面的图像对比度与相机长度作图并外推至零（即无限散射角）时，对比度表现得与卢瑟福散射公式预测的完全一致（即强度按比例缩放，与Z2成比例变化）。如果已知整体化学成分，那么这可用于确定界面或薄膜处的局部化学性质以及有效化学宽度，而无需任何额外的光谱校准方法。作为示例，详细考虑了SiGe/Si和InGaAs/Ge系统。
