Limits in detecting an individual dopant atom embedded in a crystal

作者：Mittal Anudha; Mkhoyan K Andre^*

来源：Ultramicroscopy, 2011, 111(8): 1101-1110.

DOI：10.1016/j.ultramic.2011.03.002

• Annular dark field
• Scanning transmission electron microscope
• ADF
• STEM
• Dopant
• Imaging
• High resolution
• Si
• Ge
• Simulations
• Multislice

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.

• 出版日期2011-7