Xiao Yixin, Wu Yuanpeng, Reddeppa Maddaka, Malhotra Yakshita, Guo Yifu, Yang Samuel, Liu Jiangnan, Pandey Ayush, Min Jungwook, Sun Kai, Mi Zetian
Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, Michigan 48109, United States.
Department of Materials Science and Engineering, University of Michigan, 2300 Hayward Street, Ann Arbor, Michigan 48109, United States.
Nano Lett. 2024 Oct 7. doi: 10.1021/acs.nanolett.4c03262.
III-nitride-based micro-light-emitting diodes (micro-LEDs) are currently under rapid development for next-generation high-resolution and high-brightness displays and augmented/virtual reality (AR/VR) technologies. However, it remains elusive to achieve red-emitting III-nitride micro-LEDs with a microscale size, high efficiency, and high spectral stability, posing significant impediments to the development of full-color micro-LEDs. In this work, through detailed strain engineering and control of charge carrier transport, we achieved pure red emission (≥620 nm) micro-LEDs over 2 orders of magnitude of injection current variation. We show both theoretically and experimentally that the combination of a short-period InGaN/GaN superlattice and a thick n-type GaN interlayer can not only relieve the quantum-confined Stark effect in the active region but also suppress parasitic emission from the superlattice. The optimized deep red micro-LEDs with a device lateral dimension of ∼1 μm feature a maximal external quantum efficiency of over 3% emitting at ∼660 nm.
基于III族氮化物的微发光二极管（微型发光二极管）目前正迅速发展，用于下一代高分辨率、高亮度显示器以及增强/虚拟现实（AR/VR）技术。然而，要实现具有微米级尺寸、高效率和高光谱稳定性的红色发光III族氮化物微型发光二极管仍然困难重重，这对全彩微型发光二极管的发展构成了重大障碍。在这项工作中，通过详细的应变工程和电荷载流子传输控制，我们在超过两个数量级的注入电流变化范围内实现了纯红色发射（≥620纳米）的微型发光二极管。我们从理论和实验两方面表明，短周期InGaN/GaN超晶格与厚n型GaN中间层的组合不仅可以缓解有源区的量子限制斯塔克效应，还能抑制超晶格的寄生发射。优化后的深红色微型发光二极管的器件横向尺寸约为1微米，在约660纳米处发射时的最大外部量子效率超过3%。
