Efficient GaN-based Micro-LED Arrays

Abstract

ABSTRACTHighly efficient, two-dimensional arrays of parallel-addressed InGaN blue microLEDs with individual element diameters of 8, 12 and 20μm have been fabricated. In order to overcome the difficulty of interconnecting multiple device elements with sufficient step-height coverage for contact metallisation, a novel scheme involving the etching of sloped-sidewalls has been developed. The devices have I-V characteristics similar to those of broad-area reference LEDs fabricated from the same wafer, and give superior (3mW) light output in the forward direction to the reference LEDs, despite much lower active area. The external efficiencies of the micro-LED arrays improve as the dimensions of the individual elements are scaled down. This is attributed to scattering at the etched sidewalls of in-plane propagating photons into the forward direction.