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Artificial bright spots in atomic-resolution high-angle annular dark field STEM images
T Yamazaki1, M Kawasaki, K Watanabe
1Department of Physics, Science University of Tokyo, Japan. a1299660@rs.kagu.sut.ac.jp
Journal of Electron Microscopy
|March 29, 2002
Summary
Simulations explain artificial bright spots in high-angle annular dark field scanning transmission electron microscope (HAADF STEM) images. Thermal diffuse scattering and probe function effects, not actual atoms, cause these artifacts in silicon and strontium titanate.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Electron Microscopy
Background:
- Atomic resolution imaging using high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) can reveal artifacts.
- Artificial bright spots are observed in HAADF STEM images of materials like silicon (Si) and strontium titanate (SrTiO3).
Purpose of the Study:
- To investigate the origin of artificial bright spots in HAADF STEM images.
- To explain the phenomenon using simulations based on Bloch wave description.
Main Methods:
- Simulations using Bloch wave description for electron scattering.
- Analysis of HAADF STEM images of [011]-oriented Si and [001]-oriented SrTiO3.
Main Results:
- Bright spots in Si images arise from thermal diffuse scattering from surrounding Si atoms.
- Bright spots in SrTiO3 images are attributed to Sr and Ti atoms, not oxygen atoms.
- The incident electron probe function offers a straightforward explanation for these artificial spots.
Conclusions:
- Artificial bright spots in HAADF STEM are not indicative of atomic column presence.
- Understanding scattering and probe characteristics is crucial for accurate interpretation of HAADF STEM images.