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The microstructure, local indium composition and photoluminescence in green-emitting InGaN/GaN quantum wells
N Chery1, T H Ngo2, M P Chauvat1
1CIMAP, 6 Boulevard du Maréchal Juin, Caen, France.
Journal of Microscopy
|October 13, 2017
Summary
Indium fluctuations in indium gallium nitride/gallium nitride (InGaN/GaN) quantum wells affect light emission. These variations in indium composition correlate with reduced peak intensity and broader emission in green-emitting heterostructures.
Area of Science:
- Materials Science
- Solid State Physics
- Semiconductor Nanostructures
Background:
- Indium gallium nitride (InGaN) / gallium nitride (GaN) quantum wells (QWs) are crucial for optoelectronic devices, particularly light-emitting diodes (LEDs).
- Understanding the correlation between material composition and optical properties is vital for optimizing device performance and color tuning.
Purpose of the Study:
- To analyze the microstructure and local chemical composition of green-emitting InGaN/GaN QW heterostructures.
- To correlate observed indium composition fluctuations with the photoluminescence (PL) emission properties.
Main Methods:
- High-quality InGaN/GaN QW samples grown by metalorganic vapor-phase epitaxy (MOVPE) with nominal indium compositions of x = 0.15 and 0.18.
- Scanning transmission electron microscopy (STEM) for microstructure analysis.
- Quantitative evaluation of local indium composition by comparing STEM images with simulations.
- Extraction of local indium concentration from intensity measurements.
Main Results:
- Detailed analysis of two high-structural-quality InGaN/GaN QW samples.
- Quantitative assessment of local indium composition and its fluctuations.
- Correlation established between indium fluctuations and the broadening and intensity decrease of the photoluminescence emission peak.
Conclusions:
- Local indium composition fluctuations in InGaN/GaN QWs are significant.
- These fluctuations directly impact the optical emission characteristics, leading to wider emission spectra and reduced intensity.
- Findings provide insights into controlling InGaN material quality for improved optoelectronic device performance.
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