In Situ X-Ray Study During Thermal Cycle Treatment Combined with Complementary Ex Situ Investigation of InGaN Quantum...

Area of Science:

• Semiconductor Physics
• Materials Science
• Nanotechnology

Background:

• Indium Gallium Nitride/Gallium Nitride (InGaN/GaN) quantum wells (QWs) are crucial for optoelectronic devices.
• Understanding thermal stability is vital for device performance and fabrication processes.
• Metal-organic vapor phase epitaxy (MOVPE) is a standard technique for growing these heterostructures.

Purpose of the Study:

• To investigate the in situ thermal behavior of InGaN/GaN QWs during heating and cooling cycles.
• To analyze the evolution of indium concentration distributions (ICDs) and structural changes.
• To correlate structural modifications with photoluminescence properties.

Main Methods:

• In situ X-ray reciprocal space mapping during thermal cycling.
• Simulation of radial diffraction profiles to determine ICDs.
• Ex situ high-resolution transmission electron microscopy (Ex-HRTEM) for defect analysis.

Main Results:

• Indium concentration homogenization observed between 850°C and 920°C, reducing ICDs.
• Decomposition initiated in the bottom QW (1. QW) at 940°C, with indium content decreasing.
• Further heating to 1000°C led to decomposition propagation, void formation, and increased defect area upon cooling.
• Four types of defects formed, impacting photoluminescence intensity without shifting emission wavelength.

Conclusions:

• Thermal treatment significantly alters InGaN/GaN QW structure and indium distribution.
• Decomposition of the bottom QW is a critical process influencing material properties.
• Defect formation during cooling amplifies scattering and affects optoelectronic performance.