Enhanced external quantum efficiencies of AlGaN-based deep-UV LEDs using reflective passivation layer

Area of Science:

• Optoelectronics
• Materials Science
• Semiconductor Devices

Background:

• Deep ultraviolet light-emitting diodes (DUV-LEDs) are crucial for various applications.
• Efficiency droop remains a significant challenge in DUV-LED performance.
• Advanced material engineering is needed to overcome these limitations.

Purpose of the Study:

• To investigate the impact of a novel reflective passivation layer (RPL) on DUV-LED performance.
• To analyze the RPL's effectiveness in mitigating efficiency droop.
• To evaluate the RPL's influence on light output power across different p-GaN thicknesses.

Main Methods:

• Fabrication of DUV-LEDs with and without a HfO2/SiO2-based RPL.
• Deposition of the RPL as distributed Bragg reflectors on DUV-LED structures.
• Characterization of external quantum efficiency (EQE) and light output power (LOP) at various injection currents (500 mA and 1000 mA).

Main Results:

• The RPL significantly improved LOP by 18.4% and 39.4% (at 500 mA) and 17.9% and 37.9% (at 1000 mA) for thick and thin p-GaN, respectively.
• Efficiency droop was reduced by the RPL, with notable improvements observed in DUV-LEDs with thin p-GaN.
• DUV-LEDs incorporating the RPL demonstrated enhanced overall performance and reduced efficiency roll-off.

Conclusions:

• The developed RPL, utilizing HfO2/SiO2 stacks, effectively enhances DUV-LED performance.
• The RPL shows significant potential for improving light output power and mitigating efficiency droop in DUV-LEDs.
• This study highlights the RPL as a promising technology for future DUV-LED development.