Mitigating damage in GaN-based micro-LEDs by altering the sidewall crystal orientation via constructing hexagonal mesa structures

Size effects limit the application of GaN-based Micro-LEDs in advanced display technologies. To mitigate these size effects, a mesa-structured Micro-LED with a full m-faceted hexagonal facet is proposed, unlike the traditional square structure. Results show that, through the synergistic effect of crystal facet selection and structural optimization, the full m-plane hexagonal Micro-LED is less affected by dry etching and sidewalls, thus significantly improving its photoelectric properties. With decreasing size, the peak EQE of the hexagonal Micro-LED decreases from 15.95% to 14.76%, while the peak EQE of the square Micro-LED decreases from 15.67% to 13.96%. This work provides a new, to the best of our knowledge, fabrication process for suppressing size effects and developing small-sized, high-efficiency Micro-LEDs.