Improved Performance of Passive-Matrix Micro-LED Displays Using a Multi-Function Passivation Structure

The enhanced light output efficiency of passive-matrix micro light-emitting-diode (LED) display was achieved by employing the tapered sidewalls and distributed-Bragg-reflector (DBR) passivation structure. The oblique angles at the bottom of multi-quantum wall and n-GaN are 48.9° and 21.8°, which can favor the planarization structure of pixel interconnection. As increasing the number of DBR (SiO $_2$ /TiO $_2$ ) stacking from 3.5 to 5.5 pairs, the reflectance increased obviously from 81.4% to 98.0% at the wavelength of 450 nm. As the micro-LED display with a multi-function DBR structure, the output power of 1.07 mW under 1mA, the external-quantum efficiency of 42% under 0.2 mA, and the luminance of 435 nits were obtained.