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Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope
Published on: May 28, 2016
Effect of sample bending on diffracted intensities observed in CBED patterns of plan view strained samples.
F Houdellier1, D Jacob, M J Casanove
1CEMES/CNRS, 31055 Toulouse, France. florent@cemes.fr
Ultramicroscopy
|June 5, 2007
Summary
Sample bending significantly alters electron diffraction patterns in semiconductor thin films. Chemical thinning induces substrate bending, affecting Bragg lines, while mechanical thinning shows minimal bending and subtle intensity changes.
Area of Science:
- Materials Science
- Solid State Physics
- Nanotechnology
Background:
- Transmission electron microscopy (TEM) is crucial for analyzing semiconductor nanostructures.
- Understanding how sample preparation affects electron diffraction is vital for accurate analysis.
- Strained semiconductor layers like GaInAs on GaAs are technologically important.
Purpose of the Study:
- To investigate the impact of sample bending on diffracted intensities in GaInAs/GaAs thin films.
- To correlate sample thinning methods with observed diffraction pattern variations.
- To elucidate the role of substrate strain and displacement fields in modifying electron diffraction.
Main Methods:
- Convergent beam electron diffraction (CBED) was employed for analysis.
- Finite element modeling (FEM) was used to simulate sample strain.
- Dynamical multibeam simulations were performed to calculate diffracted intensities.
- Comparison between chemically and mechanically thinned samples was conducted.
Main Results:
- Chemical thinning induced significant substrate bending, altering both kinematical and dynamical Bragg lines.
- Mechanical thinning resulted in negligible bending, leaving kinematical lines unaffected but causing slight asymmetry in dynamical lines.
- Simulations accurately reproduced experimental observations, confirming the influence of inhomogeneous displacement fields.
Conclusions:
- Sample preparation methods critically influence electron diffraction intensities in TEM.
- Substrate bending due to thinning is a primary cause of observed intensity variations.
- FEM and dynamical simulations are effective tools for understanding these effects in semiconductor nanostructures.
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