Improving the luminous efficiency of GaN-based micro-LEDs by integrating micro–nanostructures

The significant reduction in chip size introduces severe sidewall etching damage, leading to reduced quantum efficiency of micro-LEDs. Furthermore, luminous efficiency is limited by the refractive index mismatch at the p-GaN/air interface and optical losses induced by surface metal electrodes. In this work, we numerically and experimentally investigated the effects of integrating microlens arrays and nanolens arrays on the luminous efficiency of conventional micro-LEDs. At an injection current density of 100<i>A</i>/<i>c</i><i>m</i>², the luminance of <i>S</i><i>i</i><i>O</i>₂ thin-film micro-LEDs, microlens arrays micro-LEDs, and nanolens arrays micro-LEDs with a mesa diameter of 60 µm is increased by 11.87%, 19.60%, and 30.02% compared with conventional micro-LEDs, respectively. We also studied the influence of size effect on the luminous efficiency of micro-LEDs, where larger sizes correspond to higher luminous efficiency. This work provides significant insights into how integrating micro-nanostructures on micro-LEDs improves the luminous efficiency.