Enhancing the Optoelectronic Performance of InGaN-Based RGB Micro-LEDs via a DBR/Ag Composite Structure for Display Applications

InGaN-based microscale light-emitting diodes (micro-LEDs) are emerging as a pivotal technology for next-generation displays. Nevertheless, achieving high-quality displays requires overcoming critical challenges such as insufficient quantum efficiency and wavelength instability, particularly in InGaN red micro-LEDs. This study designed and fabricated composite structures comprising Si3N4/SiO2-based distributed Bragg reflector (DBR) and Ag film, which were integrated with red, green, and blue (RGB) micro-LEDs. For micro-LEDs with peak wavelengths of 623, 521, and 437 nm, the structures exhibit wide reflection bands of 384, 391, and 379 nm, respectively, each with a peak reflectance of 99%. The results demonstrated that the light extraction efficiency (LEE) was significantly enhanced, reaching 30.5%, 39.6%, and 27.4% at a current density of 10 A/cm2 for RGB micro-LEDs, respectively. Correspondingly, the external quantum efficiency (EQE) of the RGB micro-LEDs increased by 30.27%, 25.83%, and 18.48%. Notably, the full widths at half maximums (FWHMs) and peak wavelengths remained stable, indicating excellent spectral stability. Furthermore, integrating the DBR optimized for green micro-LED onto red micro-LED enabled stable emission beyond 630 nm, significantly enhancing the wavelength stability. As a result, the color gamut was expanded to 102% of the NTSC standard. These findings provide valuable insights and guidance for enhancing the optoelectronic performance of InGaN-based micro-LED displays in the future.