Improving the Electrical and Optical Characteristics of AlGaInP Red Micro-LEDs by Double Dielectric Passivation

This study presents a comprehensive investigation into the optimization of AlGaInP-based red micro-light emitting diodes (LEDs) by implementing double dielectric passivation layers. We employed a two-step passivation process that combined atomic layer deposition (ALD) for a thin Al2O3 layer and plasma-enhanced chemical vapor deposition (PECVD) for a thicker dielectric layer to passivate the sidewalls of the LEDs. After double-passivation, the devices exhibited significantly reduced leakage current compared with their non-passivated counterparts. Notably, the passivated LEDs consistently demonstrated lower ideality factors across all size variations. The Al2O3-SiNx passivated devices exhibited a remarkable 38% increase in optical power at a current density of 1000 A cm-2, along with a noteworthy 41% improvement in the external quantum efficiency (EQE) at a current density of 7 A cm-2 compared to the reference devices. In addressing the challenge of efficiency degradation in AlGaInP-based red micro-LEDs, this study underscores the effectiveness of dual dielectric passivation, emphasizing the superiority of Al2O3-SiNx as a passivation material. These findings hold promise for micro-LED technology and microdisplays, particularly in applications such as augmented reality by significantly enhancing electrical and optical performance.