60‐4: Minimal Efficiency Degradation and Elevated Radiometric Power Density of Ultraviolet‐A Micro‐LED with Homoepitaxial Structure

Abstract

As display technology continues to advance, UVA micro‐LEDs are becoming increasingly important in a variety of display and beyond‐display applications. In this study, we investigate the optoelectronic characteristics of UVA micro‐LEDs based on a homogeneously epitaxial structure on freestanding gallium nitride (GaN) substrates. The device exhibits a central wavelength of 390 nm, positioned at the overlap of UVA and visible light spectra. It demonstrates an impressively low ideality factor of 1.49 at 2.86 V and a series resistance of 9.88 O beyond 3 V. Optically, our device shows virtually no wavelength shift across a wide current density range of 0.1‐1000 A/cm2, indicating exceptional optical stability and color accuracy. The emitted light is typical purple, reaching an expansive color gamut of 115.3% of Rec.2020. Furthermore, the GaN‐on‐GaN structure, with its superior crystal structure and heat dissipation properties, results in a very low droop ratio in EQE. This ensures sustained highpower output at high current densities, showcasing great potential in applications such as 3D printing, maskless photolithography, and fluorescence tagging.