Improving the efficiency of micro-LEDs at high current densities employing a micro-current spreading layer-confined structure

• Published in: Applied physics. B, Lasers and optics Lasers and optics, 2022-07, Vol.128 (7), Article 121
• Main Authors: Liu, Xiaoyan, Yuan, Zexing, Zhou, Gufan, Yin, Pan, Shan, Xinyi, Tao, Langyi, Yu, Jinghao, Cui, Xugao, Tian, Pengfei
• Format: Article
• Language: English
• Subjects: Applied physics; Current density; Density distribution; Engineering; High current; Lasers; Low currents; Optical Devices; Optics; Photonics; Physical Chemistry; Physics; Physics and Astronomy; Quantum efficiency; Quantum Optics
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s00340-022-07839-2

In this paper, a micro-current spreading layer (mCSL)-confined micro-LED is proposed and fabricated. The mCSL is used to restrict the current channel in the 300 μm mesa of the micro-LED. Simulation results show that the internal quantum efficiency (IQE) of the mCSL-confined micro-LED is lower at low current densities, while it is higher at high current densities, compared with conventional micro-LED without mCSL. The current density distribution and the recombination rate are analyzed to prove the better restriction of the current channel at higher current density, resulting in enhanced efficiency at higher current density. With the decrease of the size of the mCSL, the efficiency of the mCSL-confined micro-LED decreases at low current densities, but increases at high current densities. This work provides a theoretical foundation for the structure design of LEDs in the future to optimize the efficiency of micro-LEDs in different applications such as display and communication.