GaN-based ultraviolet light-emitting diodes with AlN/GaN/InGaN multiple quantum wells

Area of Science:

• Semiconductor Physics
• Materials Science
• Optoelectronics

Background:

• Conventional ultraviolet light-emitting diodes (UV LEDs) often utilize aluminum gallium nitride/indium gallium nitride (AlGaN/InGaN) multi-quantum-wells (MQWs).
• Improving the light output power and operational stability of UV LEDs is crucial for various applications.

Purpose of the Study:

• To investigate the performance enhancement of UV LEDs by employing aluminum nitride/gallium nitride/indium gallium nitride (AlN/GaN/InGaN) MQWs.
• To compare the light output power, forward voltage, reverse leakage current, and electrostatic discharge (ESD) robustness of AlN/GaN/InGaN MQW UV LEDs against AlGaN/InGaN MQW UV LEDs.

Main Methods:

• Fabrication and characterization of UV LEDs with AlN/GaN/InGaN MQWs.
• Comparative analysis of electrical and optical properties, including forward voltage, light output power at 350 mA, reverse leakage current at -20 V, and 2-kV human body mode (HBM) ESD test yields.

Main Results:

• AlN/GaN/InGaN MQW UV LEDs demonstrated comparable forward voltages (3.21 V to 3.29 V at 350 mA) to AlGaN/InGaN MQW UV LEDs.
• Significant light output power enhancement was observed, reaching up to 26.7% at 375 nm emission wavelength for AlN/GaN/InGaN MQW UV LEDs.
• AlN/GaN/InGaN MQWs exhibited superior InGaN thickness uniformity, better well/barrier interface quality, and reduced large-size pits, leading to lower reverse leakage currents and improved ESD pass yield (85% vs. 70%).

Conclusions:

• AlN/GaN/InGaN MQW structures offer a promising alternative for developing high-performance UV LEDs.
• The enhanced material quality and device robustness of AlN/GaN/InGaN MQW UV LEDs translate to improved light output power and reliability.