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

Microscale light-emitting diodes (μ-LEDs) are widely employed in advancing next-generation solid-state display technology. However, the damage on the sidewalls of μ-LEDs is inevitable as the pixel size decreases which leads to a severe decline in μ-LED performance because of an increased proportion of sidewall to the emissive surface area. In this study, we fabricate AlGaInP red μ-LEDs of distinct pixel sizes (20 × 20 µm², 50 × 50 µm², and 100 × 100 µm²) to investigate the influence of different types of passivation materials on enhancing the μ-LED performance. Three different passivation materials such as SiO₂, Al₂O₃, and Si₃N₄ are utilized to explore the improvement of μ-LED performance. Among them, the μ-LED (20 × 20 µm²) with Al₂O₃ passivation displays a 140 % higher optical output power compared to bare μ-LEDs. Similarly, the current density of the μ-LED with the Al₂O₃ passivation improved by ∼ 215 % and ∼ 495 % at 5 V compared to the μ-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 μ-LEDs performance by reducing the dangling bonds at the sidewalls. Thus, an effective passivation layer can enhance its μ-LED performance by regulating the non-radiative surface defects at the sidewalls suitable for fabricating next-generation high-resolution μ-LEDs.