20.8% Peak External Quantum Efficiency of Red (619 nm) InGaN/GaN MicroLEDs

Abstract Red-emitting indium gallium nitride (InGaN) micro-light-emitting diodes (μLEDs) remain challenging due to reduced radiative efficiency at the high indium compositions required for long-wavelength emission. Here, we demonstrate InGaN/GaN red μLEDs emitting at 619 nm that are laterally enclosed by an annular distributed Bragg reflector (DBR) to enhance light extraction. Fully packaged devices exhibit peak external quantum efficiencies as high as 20.8% and wall-plug efficiencies of 13.2%, placing them as the highest-performing planar (non-V-defect engineered) red GaN μLEDs on sapphire substrates reported to date. In addition to high efficiency, the devices demonstrate strong thermal robustness, maintaining >74% of their room-temperature light output at 200 °C under high injection conditions with <8 nm peak wavelength shift. These overall results highlight laterally enclosed reflector architectures as a scalable approach for achieving efficient LED emission and, in conjunction with the natural thermal resilience of GaN devices, enable thermally resilient red μLEDs for applications in optical interconnects, visible-light communication, and next-generation displays.