Enhancing the external quantum efficiency of GaN-based micro-LEDs using an InGaN quantum well/quantum dot composite structure with an AlGaN interlayer

InGaN/GaN self-organized quantum dots (QDs) exhibit stronger carrier localization due to their three-dimensional confinement. Utilizing a quantum well/quantum dot (QW/QD) composite structure as the active region in LED can significantly enhance luminous efficiency. This study investigates GaN-based micro-LEDs featuring a QW/QD composite structure with an (Al)GaN interlayer. Experimental results reveal that QDs with an (Al)GaN interlayer exhibit reduced diameters and increased aspect ratios. Notably, an AlGaN interlayer with 10% Al composition optimally enhances QD carrier localization, promoting radiation recombination. Consequently, the peak external quantum efficiency (EQE) of 5 μm micro-LEDs with an Al 0.1 Ga 0.9 N interlayer reaches 7.3%, an 87.4% improvement compared to those devices without an interlayer. Moreover, the micro-LEDs with an Al 0.1 Ga 0.9 N interlayer demonstrate enhanced wavelength stability, narrowest full-width at half maximum (FWHM), and the lowest reverse leakage current.