We obtained high-quality AlGaInN/GaN quantum wells (QWs) with a 385 nm emission by adding Al sources to GaInN QWs grown at a low growth pressure of 150 mbar. When AlGaInN QWs were grown at a relatively high growth pressure of 400 mbar, a considerable amount of peculiar trench-shaped defects were observed on the surface of the AlGaInN QWs. We found that the trench defects acted as nonradiative centers, leading to low photoluminescence (PL) intensities. Our experiments reveal that a low growth pressure is effective in suppressing the trench defect formation, resulting in high-quality AlGaInN QWs.

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