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Towards full-color GaN micro-cavity LEDs
Researchers from Southern University of Science and Technology (SUSTech), Xiamen University, King Abdullah University of Science and Technology (KAUST), and Mie University have demonstrated a single indium gallium nitride (InGaN) micro-cavity light-emitting diode (MCLED) with a 260nm spectral tuning range covering nearly 70% of the visible spectrum, marking a key step toward monolithic full-color displays. Published in *Optics Express* on 3 September 2026, the device achieves broadly tunable, narrow-linewidth emission from red (~632nm) through green to blue (456nm) under current injection, with a full-width at half-maximum below 8nm—significantly improving color purity over prior quantum-dot designs. The epitaxial structure, grown by metal-organic chemical vapor deposition (MOCVD) on patterned sapphire, integrates blue and red InGaN quantum wells with distributed Bragg reflectors (DBRs) and an AlN aperture for thermal management. Electroluminescence spans 420nm to 680nm, with the green peak strongest. The team attributes tunability to Purcell-enhanced spontaneous emission, band-filling effects, and screening of the quantum-confined Stark effect. Peak external quantum efficiency (EQE) reached 7.68% at low current density but dropped to ~0.2% at high injection due to Auger recombination in the 10μm aperture. Maximum light output power was 264mW (336kW/cm²) with a 6.3V turn-on. To address unbalanced RGB intensity, the researchers propose time-multiplexed driving to equalize brightness. While promising, the device faces thermal dissipation and uniformity challenges, limiting immediate practical application. This work advances GaN-based resonant-cavity LEDs for next-generation displays and solid-state lighting.