Threading dislocations in GaN and GaInN multiple quantum wells and epitaxially lateral overgrown GaN were categorized into 3 types of line defect (edge, screw and mixed dislocations). It was confirmed, by cathodoluminescence measurements, that not only screw and mixed dislocations but also edge dislocations acted as non-radiative centers in GaN. Epitaxial lateral overgrowth techniques could reduce the densities of all line-defects in a several μm-wide wing region. Growth steps in the wing region were disturbed by the defects which were left in a seed region, and a complicated structure was formed at the surface of GaN and GaInN layers grown onto epitaxially lateral overgrown GaN at low temperatures. It was believed that this surface structure, formed by a high supersaturation, was a cause of In compositional spatial fluctuations and phase separation in GaInN.

Threading Dislocations and Optical Properties of GaN and GaInN. T.Miyajima, T.Hino, S.Tomiya, K.Yanashima, H.Nakajima, Y.Nanishi, A.Satake, Y.Masumoto, K.Akimoto, T.Kobayashi, M.Ikeda: Physica Status Solidi B, 2001, 228[2], 395-402