AlGaN-based deep-ultraviolet self-monitoring micro-LED arrays

Monolithic integration of micro-light emitting diodes ( μ LEDs) arrays, waveguide, and photodiodes (PD) was achieved on 275 nm deep-ultraviolet (DUV) LED epitaxial wafers, enabling in-situ self-monitoring μ LED arrays. It revealed significant size-dependent effects on the electrical and optical characteristics of μ LEDs. Arrays with mesa diameters of 220 μ m, 140 μ m, and 60 μ m exhibited enhanced current spreading, where the 60- μ m devices achieved peak external quantum efficiency (EQE) of 4.19%, optical power density of 5.65 W/cm 2 , and maximum light output power (LOP) of 45 mW per integrated chip. During 60 μ m μ LED arrays operation, the integrated self-driven PD achieved a photocurrent-to-dark-current ratio (PDCR) of 10 6 . Finally, ray-tracing simulations verified the distinct advantages of TM and TE mode photons in waveguide transverse propagation and light extraction, respectively. The compact monolithic DUV μ LED chip demonstrated stable operation at high current densities, enabling it as a promising light source for OWC systems.