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:10.1038/s41377-024-01639-3

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

Light Sci Appl. 2024 Oct 9;13(1):284. doi: 10.1038/s41377-024-01639-3.

Authors

Haifeng Wu^#¹, Xiao Lin^#^{1

2}, Qin Shuai¹, Youliang Zhu^{1

2}, Yi Fu³, Xiaoqin Liao¹, Yazhou Wang², Yizhe Wang¹, Chaowei Cheng⁴, Yong Liu¹, Lei Sun⁵, Xinyi Luo¹, Xiaoli Zhu¹, Liancheng Wang⁴, Ziwei Li¹, Xiao Wang¹, Dong Li⁶, Anlian Pan^{7

8}

Affiliations

¹ Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Institute of Optoelectronic Integration, College of Materials Science and Engineering, School of Physics and Electronics, Hunan University, 410082, Changsha, China.
² Innovision Technology (Suzhou) Co. Ltd, 215000, Suzhou, China.
³ Lattice Power (Jiangxi) Corp., 330029, Nanchang, China.
⁴ College of Mechanical and Electrical Engineering, Central South University, 410083, Changsha, China.
⁵ Beijing Digital Optical Device IC Design Co. Ltd, 100015, Beijing, China.
⁶ Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Institute of Optoelectronic Integration, College of Materials Science and Engineering, School of Physics and Electronics, Hunan University, 410082, Changsha, China. [email protected].
⁷ Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Institute of Optoelectronic Integration, College of Materials Science and Engineering, School of Physics and Electronics, Hunan University, 410082, Changsha, China. [email protected].
⁸ School of Physics and Electronics, Hunan Normal University, 410081, Changsha, China. [email protected].

^# Contributed equally.

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.