Removing plasma-induced sidewall damage in GaN-based light-emitting diodes by annealing and wet chemical treatments

The effects of thermal annealing and wet chemical treatments on the electrical characteristics of GaN-based light emitting diodes (LEDs) integrated with a microhole array were studied. It was found that KOH can etch off the plasma-damaged materials, leading to a complete suppression of surface leakage currents. It, however, attacked metal contacts and compromised the forward turn-on characteristics. Thermal annealing removed damage in the near-surface bulk region, whereas (NH4)2S treatment only passivated surface states. Both methods produced a partial recovery of the electrical characteristics of the perforated LEDs. It has been found that a complete removal of plasma damage in the perforated LEDs can be realized by thermal annealing used in conjunction with sulfide passivation.