Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
Ultramicroscopy. 2011 Jul;111(8):1101-10. doi: 10.1016/j.ultramic.2011.03.002. Epub 2011 Mar 21.
Annular dark field scanning transmission electron microscope (ADF-STEM) images allow detection of individual dopant atoms located on the surface of or inside a crystal. Contrast between intensities of an atomic column containing a dopant atom and a pure atomic column in ADF-STEM image depends strongly on specimen parameters and microscope conditions. Analysis of multislice-based simulations of ADF-STEM images of crystals doped with one substitutional dopant atom for a wide range of crystal thicknesses, types and locations of dopant atom inside the crystal, and crystals with different atoms reveal some interesting trends and non-intuitive behaviours in visibility of the dopant atom. The results provide practical guidelines to determine the optimal microscope and specimen conditions to detect a dopant atom in experiment, obtain information about the 3-d location of a dopant atom, and recognize cases where detecting a single dopant atom is not possible.
环形暗场扫描透射电子显微镜（ADF-STEM）图像可用于检测位于晶体表面或内部的单个掺杂原子。ADF-STEM 图像中含有掺杂原子的原子列与纯原子列之间的强度对比度强烈依赖于样品参数和显微镜条件。对晶体中掺杂一个替位掺杂原子的多晶进行基于多层的 ADF-STEM 图像模拟分析，这些晶体具有广泛的晶体厚度、掺杂原子在晶体内部的位置和类型以及不同原子的晶体，揭示了在掺杂原子可见性方面的一些有趣趋势和非直观行为。这些结果为确定最佳显微镜和样品条件以在实验中检测掺杂原子、获取关于掺杂原子三维位置的信息以及识别无法检测单个掺杂原子的情况提供了实用指南。
