Enhancing the efficiency of InGaN-based micro-LEDs using indium tin oxide p-electrodes

Here, we demonstrate replacing opaque Cr/Pt/Au metal p-electrodes with transparent indium tin oxide (ITO) p-electrodes to increase the light output of InGaN-based micro-light-emitting diodes (micro-LEDs). ITO p-electrodes exhibit high transmittance of ∼ 80% across the visible spectrum and low resistivity, while metal p-electrodes exhibit negligible transmittance and significant absorption. The 20 × 20 µm² and 50 × 50 µm² green micro-LED arrays with ITO p-electrodes yield 1.25 and 1.20 times improvement in light output power compared to conventional metal p-electrodes. The on-wafer external quantum efficiency (EQE) of ITO p-electrode devices reach 7.36% and 7.35% at a current density of ≤ 1.6 A/cm² for 20 × 20 µm² and 50 × 50 µm² arrays, while the on-wafer EQE of metal-based ones remain at 5.98% and 6.16%, respectively. This work opens a straightforward yet universal strategy for enhancing micro-LEDs' performance, as ITO p-electrodes can be seamlessly integrated into red, green, and blue micro-LED configurations.