Investigation of the size-dependent effect in green micro-scaled-LED with varied atomic layer deposition passivation thickness

Abstract In this study, the thickness-dependent impact of atomic layer deposition (ALD) passivation on green micro-scaled-light-emitting diodes (micro-scaled-LEDs) varying sizes (40 × 70 μm 2 and 100 × 200 μm 2 ) was systematically explored to mitigate sidewall defect-induced efficiency degradation. Al 2 O 3 passivation layers (0–60 nm) were integrated into devices, followed by electrical, optical, and aging analyses. Thinner passivation (30 nm) reduced reverse leakage by 23% and improved external quantum efficiency (EQE) by 10.65% in smaller devices, while thicker layers compromised light extraction due to absorption. Larger devices exhibited limited EQE gains (6.54%) and negligible thickness sensitivity. ABC + f(n) modeling confirmed suppressed Shockley-Read-Hall recombination and enhanced radiative efficiency, offset partially by Auger effects at higher carrier densities. Post-aging, passivated small devices retained 98.31% optical stability. The results emphasize a critical trade-off between defect passivation and optical losses in scaled devices, proposing dimension-specific ALD strategies for high-efficiency green micro-LEDs.