Monolithic Integration of High-Reflectivity Porous-AlGaN Distributed Bragg Reflectors for Spectral and Directional Control in Blue Resonant-Cavity Light-Emitting Diodes

Abstract Cyan-blue resonant-cavity light-emitting diodes (RC-LEDs) have been designed and fabricated to enhance directional emission by using a monolithic porous-AlGaN distributed Bragg reflector (DBR), integrating a 13-spot multiaperture array (20 μm diameter) via nitrogen ion implantation for current confinement. The RC-LED structure incorporates a 25-pair bottom porous-AlGaN DBR and a top TiO2/SiO2 dielectric DBR to form a resonant cavity. The RC-LED achieves a 5.41-fold increase in electroluminescence (EL) intensity in the normal direction compared to standard LED structures. Furthermore, the resonant cavity effect significantly narrows the EL emission linewidth from 27.9 to 14.7 nm and reduces the far-field divergence angle from 128° to 62°. The spectral purity and beam directionality were demonstrated in the RC-LEDs with a multiaperture emitting array, making them ideal candidates for short-distance plastic optical fiber communication in artificial intelligence data centers and high-resolution micro-LED displays.