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Published on: July 17, 2015
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Large area and depth-profiling dislocation imaging and strain analysis in Si/SiGe/Si heterostructures
Xin Chen1, Daniel Zuo2, Seongwon Kim3
11Department of Materials Science and Engineering,University of Illinois at Urbana-Champaign,Urbana,IL 61801,USA.
Summary
This study combines electron beam-induced current (EBIC) and X-ray diffraction reciprocal space mapping (XRD RSM) for detailed analysis of dislocations and strain in Si/SiGe/Si. These nondestructive methods reveal dislocation networks and quantify composition and strain in semiconductor layers.
Area of Science:
- Materials Science
- Semiconductor Physics
- Nanotechnology
Background:
- Characterizing defects in semiconductor heterostructures is crucial for device performance.
- Understanding dislocation networks and strain distribution is key for optimizing Si/SiGe/Si materials.
Purpose of the Study:
- To demonstrate a combined, nondestructive approach for depth-profiling dislocation imaging and quantitative composition/strain measurement.
- To analyze the distribution and density of dislocations in strained Si/SiGe/Si.
- To correlate structural defects with material composition and strain.
Main Methods:
- Utilizing electron beam-induced current (EBIC) with variable electron beam energies at low temperatures (~7 K) for depth-resolved dislocation imaging.
- Employing X-ray diffraction reciprocal space mapping (XRD RSM) for quantitative composition and strain analysis of different SiGe layers.
- Cross-validation with high-resolution scanning transmission electron microscopy (HR-STEM) for detailed structural and compositional imaging.
Main Results:
- EBIC imaging revealed dislocations in three distinct regions: deep networks in the SiGe layer, shallow misfit dislocations at the Si/SiGe interface, and threading dislocations connecting them.
- Variable electron beam energies in EBIC provided depth-profiling capabilities and improved spatial resolution for dislocation imaging.
- XRD RSM successfully separated peaks corresponding to different SiGe layers, enabling quantitative measurement of composition and strain.
- HR-STEM analysis confirmed the layered structure and the presence of dislocations within the layers, supporting the EBIC and XRD RSM findings.
Conclusions:
- The combined EBIC and XRD RSM techniques offer a powerful, nondestructive method for comprehensive characterization of semiconductor heterostructures.
- Accurate depth-profiling of dislocations and precise quantification of composition and strain are achievable.
- This approach provides critical insights into defect structures and their relationship with material properties in Si/SiGe/Si systems.
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