Deep ultraviolet light-emitting diodes with improved performance via nanoporous AlGaN template

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Deep ultraviolet light-emitting diodes (DUV LEDs) are crucial for applications like sterilization and sensing.
• Performance limitations in AlGaN-based DUV LEDs are often linked to high dislocation densities and strain.
• Novel template structures are needed to improve crystal quality and light extraction.

Purpose of the Study:

• To investigate the performance enhancement of AlGaN-based DUV LEDs using an AlGaN nanoporous template (NPT).
• To evaluate the NPT's effectiveness as a dislocation filtering and strain-relieving layer.
• To assess the impact of NPT on internal quantum efficiency (IQE) and light extraction efficiency (LEE).

Main Methods:

• Fabrication of AlGaN NPT using electrochemical etching.
• Lateral regrowth of n-AlGaN on the NPT and comparison with as-grown template (AGT).
• Characterization of material quality (dislocation density, strain) and device performance (IQE, light output power).

Main Results:

• The n-AlGaN regrown on NPT exhibited reduced dislocation density and mitigated compressive strain compared to AGT.
• A 23% improvement in internal quantum efficiency was observed for multiple quantum wells grown on NPT.
• Nanopores in NPT transformed into air voids, enhancing photon escape and light extraction efficiency.
• DUV LEDs based on NPT showed a 50% increase in light output power at 20 mA compared to AGT.

Conclusions:

• AlGaN NPT is an effective template for improving AlGaN-based DUV LED performance.
• The NPT acts as a crucial layer for defect reduction and strain management.
• The enhanced LEE and IQE contribute to a significant increase in light output power, paving the way for more efficient DUV light sources.