The impacts of SiO2 atomic-layer-deposited passivation layer thickness on GaN-based green micro-LEDs

Abstract In this study, we fabricated 76 × 127 µm2 green GaN-based micro-light-emitting-diodes (micro-LEDs) with atomic-layer-deposited (ALD) SiO2 passivation layers whose thicknesses were 0, 15, and 100 nm. The optoelectrical and communication performances of these devices were measured and analysed. The current-voltage results showed that ALD technology reduced the leakage current and enhanced the forward current of micro-LEDs. Compared with those of micro-LEDs without the passivation layer, the external quantum efficiency of micro-LEDs with 15 and 100 nm-thick SiO2 passivation layers increased by 23.64 and 19.47%, respectively. Furthermore, analysis of the EQE of the samples at room temperature using the ABC + f(n) model revealed the differences in the physical mechanisms of green micro-LEDs. Moreover, the communication performance indicated that ALD sidewall passivation reduced the carrier lifetime and improved the communication performance of green micro-LEDs.