Performance improvement of InGaN-based multiple quantum wells embedded nanoporous n-GaN layers

InGaN-based multiple quantum wells (MQWs) embedded nanoporous (NP) GaN layers were fabricated by metal-organic chemical vapor deposition (MOCVD) and followed by electrochemical (EC) etching in oxalic, HF or HNO3 electrolytes. The oxalic-etching and HF-etching do not lead to enhanced luminescence of MQWs, which should be contributed to the damage of InGaN/GaN stacking layers. For the HNO3-etching, the photoluminescence (PL) strength of MQW layer is increased by a factor of 0.52 compared with the as-grown sample, which should be contributed to stress relaxation, light scattering and reflection of quasi vertical nanopore array, and amplify spontaneous emission by resonant cavity. If the nanopore walls in NP-GaN layer are smoothed by the annealing in NH3 atmosphere, the light extraction efficiency of MQWs can be further improved. The study provides a useful method for improving the light extraction efficiency of GaN-based light emitting devices.