EBL-free strategic hybrid MQW with indium-alloyed barriers for efficient green micro-LEDs with reduced operating voltage

Green micro-light-emitting diodes (µLEDs) with sub-100 µm dimensions are crucial for next-generation display technologies but remain constrained by the persistent 'green gap' and low-current-density operation challenges. This work numerically investigates optimized epitaxial designs for 60 × 60 µm2 InGaN based green µLEDs operating at 1 A/cm- 2, exploring multiple configurations to reveal performance-enhancing innovations and their underlying mechanisms. We propose a hybrid multiple quantum well (MQW) design featuring four step-graded low-indium-content passive quantum wells paired with a single green-emitting active QW. This configuration enhances electron-hole wavefunction overlap, suppresses the quantum-confined Stark effect, and reduces the active recombination volume. Further performance improvements are achieved by eliminating the electron blocking layer to boost hole injection and introducing In-alloyed quantum barriers to reduce polarization-induced interface charges. These innovations collectively result in an 18% increase in internal quantum efficiency, a 37% reduction in operating voltage, and a 74% enhancement in wall-plug efficiency compared to the conventional high-In content identical 5- -QW structure. This simplified final design offers a scalable and cost-effective pathway toward high-efficiency green µLEDs, with implications for broader adoption in full-color micro-displays and long-wavelength III-Nitride emitters.