Enhancing the electrical and optical performance of AlGaInP-based red micro-LEDs with passivation materials

Microscale light-emitting diodes (mu-LEDs) are widely employed in advancing next-generation solid-state display technology. However, the damage on the sidewalls of mu-LEDs is inevitable as the pixel size decreases which leads to a severe decline in mu-LED performance because of an increased proportion of sidewall to the emissive surface area. In this study, we fabricate AlGaInP red mu-LEDs of distinct pixel sizes (20 x 20 mu m(2), 50 x 50 mu m(2), and 100 x 100 mu m(2)) to investigate the influence of different types of passivation materials on enhancing the mu-LED performance. Three different passivation materials such as SiO2, Al2O3, and Si3N4 are utilized to explore the improvement of mu-LED performance. Among them, the mu-LED (20 x 20 mu m(2)) with Al2O3 passivation displays a 140 % higher optical output power compared to bare mu-LEDs. Similarly, the current density of the mu-LED with the Al2O3 passivation improved by similar to 215 % and similar to 495 % at 5 V compared to the mu-LEDs passivated with SiO2 and Si3N4. Indeed, the higher ratio of Ga/Al-O bond formation at the sidewall/passivation interface is accountable for recovering mu-LEDs performance by reducing the dangling bonds at the sidewalls. Thus, an effective passivation layer can enhance its mu-LED performance by regulating the non-radiative surface defects at the sidewalls suitable for fabricating next-generation high-resolution mu-LEDs.