Redirection-Manipulated Honeycomb Inclined Reflection System Enables Highly Efficient AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes

Abstract

AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) are considered promising and efficient solid-state DUV light sources. However, extracting photons directly from high-Al-content AlGaN multiple quantum wells active region where the ratio of transverse magnetic (TM)/transverse electric (TE) polarization emission increases has long been challenging due to the total internal reflection phenomenon and re-absorption effect, leading to the low efficiency of DUV LEDs. Herein, a redirection-manipulated honeycomb inclined reflection system (HIRS) is demonstrated aimed at efficiently extracting TM- and TE-polarized light from DUV LEDs, and systematically analyze the influence of the HIRS configurations on the resulting redirection effect. Crucially, the investigation reveals the effective range of the HIRS redirection effect, prompting the proposal of a pixelation strategy applicable to generalized AlGaN-based DUV LEDs. This strategy is validated through the experimental fabrication of pixelated DUV LEDs integrated with HIRS. Compared to their non-pixelated, non-HIRS counterparts, these pixelated DUV LEDs integrated with HIRS achieve a light output power enhancement factor of up to 1.95, surpassing all previously reported pixelated DUV LEDs. Furthermore, the double-side-coated sapphire is introduced as a package plate to improve reliability and optical performance and develop a miniaturized sterilization module for effective water purification. This work not only provides guidance for high-power AlGaN-based DUV LEDs design and manufacture but also advances the development of efficient solutions for water purification.