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A Critical Comparison Among High-Resolution Methods for Spatially Resolved Nano-Scale Residual Stress Analysis in
Saqib Rashid1, Edoardo Rossi1, Spyros Diplas2
1Department of Civil, Computer Science and Aeronautical Technologies Engineering, Roma TRE University, Via Della Vasca Navale, 62, 00146 Rome, Italy.
International Journal of Molecular Sciences
|April 17, 2025
Summary
Residual stresses in multilayer coatings are complex. This study used advanced microscopy and diffraction to measure stress at different scales, finding reliable, comparable results across methods for AlGaN/GaN systems.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Physics
Background:
- Residual stresses in multilayer thin coatings are a complex multiscale phenomenon.
- Understanding stress distribution requires a multiscale measurement approach.
- Factors influencing stress include layer architecture, material properties, and deposition methods.
Purpose of the Study:
- To investigate residual stress in AlGaN/GaN multilayer coatings using a multiscale approach.
- To compare stress measurement results from different spatial resolutions.
- To validate the reliability and comparability of complementary stress analysis techniques.
Main Methods:
- Deposition of AlGaN/GaN multilayer coatings on sapphire substrates via metalorganic vapor phase epitaxy (MOVPE).
- High-resolution X-ray diffraction (HRXRD) for structural characterization.
- Focused ion beam (FIB) cross-sectioning and transmission electron microscopy (TEM) for structural analysis.
- High-Resolution Scanning Transmission Electron Microscopy-Graphical Phase Analysis (HRSTEM-GPA) for atomic-resolution strain mapping.
- Focused Ion Beam-Digital Image Correlation (FIB-DIC) for microscale stress evaluation.
Main Results:
- Epitaxial growth and structural characteristics of AlGaN/GaN coatings were confirmed by HRXRD.
- Layer structures and thicknesses were analyzed using FIB and TEM.
- Residual strain values of -3.2 × 10⁻³ (FIB-DIC) and -4.55 × 10⁻³ (HRSTEM-GPA) were obtained.
- Measurements at different spatial resolutions were found to be reliable and comparable.
Conclusions:
- Multiscale residual stress measurement techniques provide reliable and comparable data for multilayer coatings.
- A critical assessment of the characteristic scale of each method is essential for accurate interpretation.
- This study validates the combined use of HRSTEM-GPA and FIB-DIC for comprehensive stress analysis in complex thin film systems.
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