Abstract

In this Letter, beveled mesas for 30 × 30 µm² GaN-based micro-light-emitting diodes (µLEDs) with different inclination angles are designed, fabricated, and measured. We find that µLED with a mesa inclination angle of 28° has the lowest internal quantum efficiency (IQE) and the highest injection current density at which the peak IQE is obtained. This is due to the increased quantum confined Stark effect (QCSE) at the mesa edge. The increased QCSE results from the strong electric field coupling effect. Instead of radiative recombination, more nonradiative recombination and leakage current will be generated in the sidewall regions. Besides, the smallest angle (28°) also produces the lowest light extraction efficiency (LEE), which arises from the optical loss caused by the sidewall reflection at the beveled surface sides. Therefore, the inclination angle for the beveled mesa has to be increased to 52° and 61° by using Ni and SiO₂ as hard masks, respectively. Experimental and numerical results show that the external quantum efficiency (EQE) and the optical power can be enhanced for the fabricated devices. Meanwhile, the reduced surface recombination rate also decreases the leakage current.

© 2023 Optica Publishing Group

On the impact of the beveled mesa for GaN-based micro-light emitting diodes: electrical and optical properties

Sheng Hang, Gai Zhang, Chunshuang Chu, Yonghui Zhang, Quan Zheng, Qing Li, and Zi-Hui Zhang
Opt. Express 30(21) 37675-37685 (2022)

Interplay of sidewall damage and light extraction efficiency of micro-LEDs

Jeong-Hwan Park, Markus Pristovsek, Wentao Cai, Heajeong Cheong, Takeru Kumabe, Dong-Seon Lee, Tae-Yeon Seong, and Hiroshi Amano
Opt. Lett. 47(9) 2250-2253 (2022)

Size-dependent sidewall defect effect of GaN blue micro-LEDs by photoluminescence and fluorescence lifetime imaging

Zhou Wang, Xinyi Shan, Shijie Zhu, Xugao Cui, Zhilai Fang, Gengzhao Xu, Zhenghui Liu, Wentao Song, Ke Xu, and Pengfei Tian
Opt. Lett. 48(18) 4845-4848 (2023)

Enhanced light extraction of the deep-ultraviolet micro-LED via rational design of chip sidewall

Meng Tian, Huabin Yu, Muhammad Hunain Memon, Zhanyong Xing, Chen Huang, Hongfeng Jia, Haochen Zhang, Danhao Wang, Shi Fang, and Haiding Sun
Opt. Lett. 46(19) 4809-4812 (2021)

Ultra-small InGaN green micro-light-emitting diodes fabricated by selective passivation of p-GaN

Zhe Zhuang, Daisuke Iida, Martin Velazquez-Rizo, and Kazuhiro Ohkawa
Opt. Lett. 46(20) 5092-5095 (2021)