Impacts of different thickness Al2O3 and SiO2 atomic layer deposition sidewall passivation for GaN-based micro-LEDs

In this work, 76 × 127 μm2 blue micro-LEDs with 0, 15, and 60 nm Al2O3 or SiO2 passivation layers were fabricated by adopting atomic layer deposition (ALD) sidewall passivation technology, and the impacts of these ALD passivation layers for micro-LEDs were investigated. According to the measured results of current-voltage, electroluminescence, microhyperspectral imaging, and visible light communication, the technology of ALD sidewall passivation could decrease the leakage current, enhance the electroluminescence intensity, and improve the current distribution uniformity and the bandwidth of micro-LEDs. In addition, the micro-LEDs with thicker ALD sidewall passivation layers (60 nm SiO2 or Al2O3) showed significant improvement in external quantum efficiency (increase by 5.9% and 8.3%) and communication bandwidth (increase by 29.5% and 29.4%) than the devices without ALD sidewall passivation. These results give a reference for manufacturing the higher performance micro-LEDs with the technology of ALD sidewall passivation.