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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Imaging the evolution of lateral composition modulation in strained alloy superlattices
Chris Pearson1, C Dorin, J Mirecki Millunchick
1Department of Computer Science, Engineering Science, and Physics, The University of Michigan-Flint, Flint, Michigan 48502, USA.
Physical Review Letters
|March 6, 2004
Summary
Scanning tunneling microscopy revealed morphological evolution in GaAs/InAs superlattices. Islands and trenches developed spacing, indicating lateral composition modulation due to layer thickness and atomic plane variations.
Area of Science:
- Materials Science
- Surface Science
- Semiconductor Physics
Background:
- Gallium Arsenide/Indium Arsenide (GaAs/InAs) short period superlattices are crucial in semiconductor device applications.
- Understanding their morphological evolution is key to controlling material properties.
- Surface morphology significantly impacts electronic and optical characteristics.
Purpose of the Study:
- To investigate the morphological evolution of GaAs/InAs short period superlattices.
- To identify the factors driving surface morphology changes during growth.
- To provide experimental evidence for the origins of lateral composition modulation.
Main Methods:
- Utilizing Scanning Tunneling Microscopy (STM) for high-resolution surface imaging.
- Analyzing the morphology of superlattice layers grown under different strain conditions (compression and tension).
- Measuring characteristic spacing of surface features.
Main Results:
- Observed island or trench morphology in GaAs/InAs superlattice layers.
- Demonstrated growth in size of these morphological features with increasing film thickness.
- Identified a characteristic spacing of approximately 150 Angstroms along the [110] direction.
- Provided the first experimental evidence linking lateral composition modulation to thickness variations and in-plane compositional nonuniformities.
Conclusions:
- Lateral composition modulation in GaAs/InAs superlattices is experimentally confirmed.
- Morphological evolution, including island/trench formation and spacing, is driven by layer thickness variations and compositional nonuniformities.
- These findings offer critical insights for the precise fabrication of advanced semiconductor heterostructures.
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