Novel reflection system boosts efficiency of DUV LEDs

Researchers from Wuhan University and Ningbo ANN Semiconductor in China have developed a redirection-manipulated honeycomb inclined reflection system (HIRS) to significantly enhance the optoelectronic performance of AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs).

“By integrating the HIRS into the pixelated DUV LEDs, both transverse magnetic (TM) and transverse electric (TE)-polarised light are redirected to the top of the device, overcoming total internal reflection and reabsorption losses. This strategy achieves a record light output power (LOP) enhancement factor of 1.95, the highest reported for pixelated DUV LEDs,” explained Shengjun Zhou, a professor at Wuhan University who directed the research.

AlGaN-based DUV LEDs are critical for mercury-free UV light sources in sterilisation, sensing, and water purification. However, their efficiency is limited by the dominant TM-polarised light emission in high-Al-content AlGaN multiple quantum wells, which propagates laterally and suffers severe reabsorption losses due to the internal reflection effect. Conventional methods, such as pixelating DUV LED chips, inevitably reduce the area of active region and p-type contact, which in turn reduces emission power and substantially increases the operating voltage.