In-depth Investigation of Deep Ultraviolet MicroLED Geometry for Enhanced Performance

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 μ-LEDs). Specifically, we designed and fabricated three types of DUV μ-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 μ-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 μ-LED in circle shape by 29.2% at an injection current density of 3000 A/cm2. More importantly, such superior performance due to the increased P/A ratio of μ-LEDs is becoming more remarkable when the size of μ-LEDs further shrinks, attributing to a larger light extraction, more uniform current spreading, and better sidewall out-radiation of self-generated heat of the μ-LEDs.