近日，湖南大学的潘安练&李东及其研究团队取得一项新进展。经过不懈努力，他们成功制备出具有晶圆级均匀硅基氮化镓外延层的超高亮度微发光二极管。相关研究成果已于2024年10月9日在国际知名学术期刊《光：科学与应用》上发表。

本研究报道了利用高质量硅基氮化镓（GaN-on-Si）外延层制备的5微米像素高亮度绿色微显示器。首先，在硅衬底上生长出四英寸晶圆级均匀绿色氮化镓外延层，该外延层具有低位错密度（5.25×10⁸cm^-2）、小晶圆翘曲度（16.7微米）以及高波长一致性（标准差STDEV<1纳米），并可扩展至六英寸尺寸。基于这些高质量氮化镓外延层，采用垂直非对准键合技术设计了5微米像素尺寸的绿色微发光二极管（Micro-LEDs）。

通过结合湿法处理的原子级侧壁钝化方法，成功解决了微发光二极管侧壁损伤问题，并在像素顶部稳定生成纳米级表面纹理，从而释放了高质量硅基氮化镓外延片的内部量子效率。因此，绿色微发光二极管实现了超过10⁷坎德拉/平方米（尼特）的超高亮度，这是目前报道的最高结果。

此外，将微发光二极管与硅基互补金属氧化物半导体（CMOS）电路集成，实现了分辨率高达1080×780的绿色微发光二极管显示器，能够播放高清电影和图像。本研究为在大尺寸硅基氮化镓外延片上实现高亮度微发光二极管显示器的大规模生产奠定了基础。

据悉，由于具有高像素密度和亮度，基于氮化镓（GaN）的微发光二极管（Micro-LEDs）被视为革命性的显示技术，在微显示和虚拟显示领域具有重要的应用前景。然而，像素尺寸小于10微米的Micro-LEDs仍面临技术挑战，如侧壁损伤和有限的光提取效率，导致发光效率降低及亮度严重不均匀。

附：英文原文

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

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

Issue&Volume: 2024-10-09

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 5.25×10⁸cm^-2, small wafer bowing of 16.7 μm, and high wavelength uniformity (standard deviation STDEV<1nm), 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 10⁷cd/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.

DOI: 10.1038/s41377-024-01639-3

Source: https://www.nature.com/articles/s41377-024-01639-3