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Energy-filtered electron diffraction and high-resolution electron microscopy on short-range ordered structure in
Daisuke Shindo1, Yoichi Ikematsu, Chang-Woo Lee
1Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.
Journal of Electron Microscopy
|May 11, 2002
Summary
Researchers observed unique diffuse scattering in gallium arsenide antimonide (GaAs(0.5)Sb(0.5)) using electron diffraction. This scattering reveals short-range ordering of arsenic and antimony atoms during epitaxial growth.
Area of Science:
- Materials Science
- Solid State Physics
- Crystallography
Background:
- III-V alloy semiconductors like GaAs(0.5)Sb(0.5) are crucial for electronic and optoelectronic devices.
- Understanding atomic ordering is key to controlling material properties.
Purpose of the Study:
- To investigate the characteristic diffuse scattering in epitaxially grown GaAs(0.5)Sb(0.5).
- To elucidate the atomic-scale structure and ordering mechanisms in this alloy.
Main Methods:
- Energy-filtered electron diffraction with [110] incidence.
- High-resolution electron microscopy (HREM).
- Fourier transform image processing of HREM images.
Main Results:
- Observed distinct diffuse scattering patterns at one-third positions between fundamental reflections, oriented along the q002 direction.
- HREM revealed weak contrast modulations corresponding to the diffuse scattering.
- Processed HREM images showed small, elongated regions of ordered As and Sb atoms aligned along specific crystallographic planes.
Conclusions:
- The diffuse scattering is attributed to short-range ordering of As and Sb atoms during epitaxial growth.
- A simple structure model for the observed short-range order in GaAs(0.5)Sb(0.5) was proposed.
- The study highlights the utility of combining energy-filtered electron diffraction and HREM for characterizing atomic ordering in alloys.