Modulation bandwidth improvement of GaN-based green micro-LEDs array by polarization-induced p-type doping

• Published in: Applied physics letters Vol. 121; no. 3
• Main Authors: Huang, Zhen, Tao, Renchun, Li, Duo, Yuan, Zexing, Li, Tai, Chen, Zhaoying, Yuan, Ye, Kang, Junjie, Liang, Zhiwen, Wang, Qi, Tian, Pengfei, Shen, Bo, Wang, Xinqiang
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 18-07-2022
• Subjects: Aluminum gallium nitrides; Applied physics; Arrays; Bandwidths; Carrier recombination; Doping; Gallium nitrides; Light emitting diodes; Modulation; Optical communication; Polarization
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0098321

As one of the most promising candidates for signal carrier sources in visible light communication, GaN-based green micro-light emitting diodes (μ-LEDs) exhibit a limited modulation bandwidth. In this work, we propose an approach to accelerate carrier recombination rate in green μ-LEDs and, thus, improve the modulation bandwidth by enhancing p-type conductivity to allow more efficient hole injection into an active region. The polarization-induced p-type doping with graded AlGaN enhances the p-type layer conductivity to 2.5 × 10−2 S/m, which is about 4 times in magnitude higher than that of the conventional p-type GaN layer (0.6 × 10−2 S/m). 16 × 16 green μ-LEDs arrays using such graded p-AlGaN exhibit a light output power of 4.4 mW and a modulation bandwidth of 130 MHz, both showing an improvement of about 45% as compared with the ones using a pure p-GaN layer. The polarization-induced p-type doping in graded AlGaN would accelerate the application of GaN-based μ-LEDs in visible light communication.