High-temperature performance of InGaN-based amber micro-light-emitting diodes using an epitaxial tunnel junction contact

• Published in: Applied physics letters Vol. 124; no. 14
• Main Authors: Sang, Yimeng, Zhuang, Zhe, Xing, Kun, Zhang, Dongqi, Yan, Jinjian, Jiang, Zhuoying, Li, Chenxue, Chen, Kai, Ding, Yu, Tao, Tao, Iida, Daisuke, Wang, Ke, Li, Cheng, Huang, Kai, Ohkawa, Kazuhiro, Zhang, Rong, Liu, Bin
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 01-04-2024
• Subjects: Carrier lifetime; Current injection; Diameters; Efficiency; Electric contacts; Indium gallium nitrides; Light emitting diodes; Low currents; Molecular beam epitaxy; Radiative recombination; Red shift; Room temperature; Temperature; Temperature dependence; Thermal stability; Tunnel junctions
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0190000

This study investigated the temperature-dependent electroluminescent (EL) performance of InGaN-based amber micro-light-emitting diodes (μLEDs) with a diameter of 40 μm using an epitaxial tunnel junction (TJ) contact for current spreading. The TJ-μLEDs could achieve a high electrical efficiency of 0.935 and a remarkable wall-plug efficiency of 4.3% at 1 A/cm2 at room temperature, indicating an excellent current injection efficiency of the TJ layers regrown by molecular beam epitaxy. Moreover, the current injection of the amber TJ-μLEDs at the forward bias could be further improved at elevated temperatures. The improvement can be explained by the enhanced tunneling probability and acceptor ionization in p-GaN based on the theoretical simulation. The redshift coefficient, which describes the temperature-dependent peak wavelength shift, is obtained as small as 0.05 nm/K, and the high-temperature-to-room-temperature EL intensity ratio is calculated as >0.56 even at a low current density of 0.5 A/cm2 at the temperatures up to 80 °C. This thermal droop behavior was attributed to the enhanced non-radiative recombination, which was confirmed by the shorter carrier lifetime measured at high temperatures.