Role of Sidewall Conditions in the External Quantum Efficiency of InGaN‐Based Micro‐LEDs

This study aims to investigate the external quantum efficiency (EQE) of InGaN‐based blue micro light‐emitting diodes (μLEDs) depending on sidewall conditions and current stress. To this end, this study prepares two sets of InGaN blue μLEDs with sizes of 10 × 10 μm², 20 × 20 μm², and 40 × 40 μm²: 1) μLEDs with and without a 10 nm‐thick ALD‐SiO₂ interlayer and 2) μLEDs with varying atomic layer deposition (ALD)‐Al₂O₃ passivation layer thickness and tetramethylammonium hydroxide (TMAH) treatment time. The results of set 1 demonstrate that the ALD‐SiO₂ interlayer layer has a significant effect on the EQE of μLEDs only at low current densities, as the interlayer effectively protects against subsequent plasma damage. The results of current stress show that the ALD‐SiO₂ interlayer plays an important role at low current densities. The results of set 2 demonstrate that a sufficiently thick ALD passivation layer should be deposited to minimize sidewall interface states, and a short TMAH treatment time of 1 min is sufficient. The results in this study highlight that sidewall conditions have a substantial impact on the EQE at low current densities and indicate that optimizing ALD thickness and TMAH treatment time can reduce processing time and cost.