Optimizing Al Composition in Barriers for InGaN Amber Micro-LEDs With High Wall-Plug Efficiency
Yimeng Sang, Zhe Zhuang, Kun Xing, Zhuoying Jiang, Chenxue Li, Feifan Xu, Dongqi Zhang, Junchi Yu, Jianguo Zhao, Ting Zhi, Tao Tao, Cheng Li, Kai Huang, Kazuhiro Ohkawa, Rong Zhang, Bin Liu
Abstract
This study demonstrated InGaN-based amber micro-light-emitting diodes ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs) with varying Al contents of 2%, 5%, and 16% in barriers. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs with Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\mathbf {{0}.{05}}}$ </tex-math></inline-formula> GaN in barriers exhibited the highest on-wafer wall-plug efficiency due to the good material quality and optimal energy band engineering for carrier injection. We fabricated <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs with diameters ranging from 60 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\mu \text{m}$ </tex-math></inline-formula> using the optimal epi-structure. The forward voltage was 2.15 V at 1 A/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathbf {{2}}}$ </tex-math></inline-formula> , a significantly lower value compared to others. The external quantum efficiency and wall-plug efficiency of the packaged <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs with a diameter of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10 ~\mu \text{m}$ </tex-math></inline-formula> are 4.8% and 4% at 1 A/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathbf {{2}}}$ </tex-math></inline-formula> , respectively. The slight decrease in efficiency of 10- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m} \mu $ </tex-math></inline-formula> LEDs can be attributed to the sidewall effect, which was confirmed by photoluminescent and lifetime mapping.