Effect of atomic layer etching on the surface damage removal of GaN-based light emitting diodes

The effect of the optimized ALE process for the removal of surface damage of LED device with a MQW caused by GaN RIE has been investigated and compared with the damage removal by KOH-based wet etching. When the GaN and InGaN etched by RIE were processed by the optimized ALE process having the EPCs of ∼2.4 Å/cycle for GaN the complete recovery of surface atomic composition similar to the references of GaN and InGaN in addition to the removal of etch residue caused by RIE could be observed while the KOH-based wet etching did not recover the atomic composition and residue completely. However, the optimized ALE process removed the sidewall stress and defects on the MQW layers of the patterned GaN structure almost completely and especially showed the highest PL intensity for the smallest GaN pattern size having the highest surface to volume ratio, even though the lowest PL intensity was observed for the smallest pattern size after RIE. Thus, in next-generation GaN device processes where device sizes continue to be reduced, ALE will be an essential process that removes surface damage and improves device performance, making it more critical than wet etching for surface damage removal.