Repairing etched sidewall surface of InGaN/GaN micro-light emitting diode through neutral N/H radicals in high vacuums

Abstract

Sidewall defects induced in the etching process critically limit the development of high-performance, small-size gallium nitride-based light emitting diodes (LEDs). Although conventional post-etch techniques like wet chemical etching have been applied to modify the etched surface, problems such as impurity re-absorptions and modification on sidewall morphology still stand. In this work, we report a novel sidewall repair technique using a radio frequency atom source to restore sidewall defects. Treatment of neutral reactive N/H species effectively mitigates the surface Fermi level pinning and reduces the defect-related surface states. This step is directly followed by vacuum-interconnected atomic layer deposition passivation, preventing air exposure and secondary impurity adsorption. Based on this strategy, the effect of N/H treatment is more pronounced in smaller devices. For 5-μm devices, the electroluminescence intensity at a current density of 10 A/cm2 increases by approximately 34%, the peak external quantum efficiency improves by 35%, and the reverse leakage current density at −5 V is reduced from 1.30 to 9.64 × 10−6 A/cm2. This strategy provides an effective methodology aiming for sidewall repair of micro-LEDs.