Optoelectronic performance enhancement of 1–5  μ m InGaN-based micro-LEDs using chemical etching coupled with dielectric passivation

Although InGaN-based micro-light-emitting diodes (micro-LEDs) have been extensively studied as key components for next-generation display technologies, the performance of micro-LEDs smaller than 5 μm remains severely constrained by the sidewall effect, posing an urgent challenge to be addressed. This study successfully fabricated InGaN-based micro-LEDs with dimensions ranging from 1 to 5 μm by introducing a coupled chemical etching with dielectric passivation technique. It is revealed that the peak external quantum efficiency (EQE) of all devices significantly improved after coupled chemical etching, while their surface recombination velocity decreased significantly. Moreover, this enhancement in peak EQE becomes more pronounced as the device size decreases from 5 to 1 μm. APSYS simulations further indicate that as the sidewall defect density decreases, the distribution of holes across different quantum wells becomes more uniform, and the radiative recombination rate relative to the Shockley–Read–Hall rate significantly increases, which is in excellent agreement with the experimental results. More importantly, the peak EQE of 1 and 5 μm micro-LEDs reached 14.01% and 40.46%, respectively, increasing by 363% and 151% compared to that without coupled chemical etching. These findings validate the effectiveness of chemical etching coupled with dielectric passivation technology in micro-LED manufacturing, and also reveal the significant impact of sidewall defects in size-dependent efficiency.