In-Depth Investigation of Deep Ultraviolet MicroLED Geometry for Enhanced Performance
Shudan Xiao, Huabin Yu, Muhammad Hunain Memon, Hongfeng Jia, Yuanmin Luo, Rui Wang, Haiding Sun
Abstract
In this work, we demonstrate a straightforward and effective strategy, so called perimeter-to-area ratio (P/A ratio) engineering, to enhance the optical performance of deep-ultraviolet micro-scale LED (DUV <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). Specifically, we designed and fabricated three types of DUV <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 architectures with circle, pentagon, and quadrangle shapes which possess different P/A ratios, and found that the external quantum efficiency (EQE) of the quadrilateral <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 exhibit the highest value thanks to its largest P/A ratio in the LED mesa covered by the p-electrode, leading to a higher light output power than that of <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> -LED in circle shape by 29.2% at an injection current density of 3000 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> . More importantly, such superior performance due to the increased P/A ratio of <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 is becoming more remarkable when the size of <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 further shrinks, attributing to a larger light extraction, more uniform current spreading, and better sidewall out-radiation of self-generated heat of 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.