Light: Science & Applications (Oct 2024)

Ultra-high brightness Micro-LEDs with wafer-scale uniform GaN-on-silicon epilayers

  • Haifeng Wu,
  • Xiao Lin,
  • Qin Shuai,
  • Youliang Zhu,
  • Yi Fu,
  • Xiaoqin Liao,
  • Yazhou Wang,
  • Yizhe Wang,
  • Chaowei Cheng,
  • Yong Liu,
  • Lei Sun,
  • Xinyi Luo,
  • Xiaoli Zhu,
  • Liancheng Wang,
  • Ziwei Li,
  • Xiao Wang,
  • Dong Li,
  • Anlian Pan

DOI
https://doi.org/10.1038/s41377-024-01639-3
Journal volume & issue
Vol. 13, no. 1
pp. 1 – 11

Abstract

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Abstract Owing to high pixel density and brightness, gallium nitride (GaN) based micro-light-emitting diodes (Micro-LEDs) are considered revolutionary display technology and have important application prospects in the fields of micro-display and virtual display. However, Micro-LEDs with pixel sizes smaller than 10 μm still encounter technical challenges such as sidewall damage and limited light extraction efficiency, resulting in reduced luminous efficiency and severe brightness non-uniformity. Here, we reported high-brightness green Micro-displays with a 5 μm pixel utilizing high-quality GaN-on-Si epilayers. Four-inch wafer-scale uniform green GaN epilayer is first grown on silicon substrate, which possesses a low dislocation density of 5.25 × 108 cm− 2, small wafer bowing of 16.7 μm, and high wavelength uniformity (standard deviation STDEV < 1 nm), scalable to 6-inch sizes. Based on the high-quality GaN epilayers, green Micro-LEDs with 5 μm pixel sizes are designed with vertical non-alignment bonding technology. An atomic sidewall passivation method combined with wet treatment successfully addressed the Micro-LED sidewall damages and steadily produced nano-scale surface textures on the pixel top, which unlocked the internal quantum efficiency of the high-quality green GaN-on-Si epi-wafer. Ultra-high brightness exceeding 107 cd/m2 (nits) is thus achieved in the green Micro-LEDs, marking the highest reported results. Furthermore, integration of Micro-LEDs with Si-based CMOS circuits enables the realization of green Micro-LED displays with resolution up to 1080 × 780, realizing high-definition playback of movies and images. This work lays the foundation for the mass production of high-brightness Micro-LED displays on large-size GaN-on-Si epi-wafers.