Optimization of SiO2 passivation layer thickness for performance enhancement of AlGaInP-based Micro-LEDs

We investigate the effect of PECVD-grown SiO 2 passivation layers (50–300 nm) on the electrical and optical properties of 7 μm AlGaInP-based red Micro-LEDs. A 100 nm layer gives the best overall performance, whereas thinner and thicker films both degrade the device efficiency. Sidewall-targeted time-resolved photoluminescence measurements show that the average carrier lifetime increases from 0.47 ns for the unpassivated device to 0.89 ns for the 100 nm layer and decreases again for thicker films, in agreement with the electrical and optical results. These results reveal the two competing effects of the passivation thickness and provide process guidance for the low-cost mass production of small-size Micro-LEDs.