Influence of strain-induced indium clustering on characteristics of InGaN/GaN multiple quantum wells with high indium composition

We report the effect of strain-induced indium clustering on the emission properties of InGaN/GaN multiple quantum wells grown with high indium composition by metalorganic chemical vapor deposition. Indium clustering confirmed by high-resolution transmission electron microscopy results in the redshift of the emission peak and the increase of the integrated photoluminescence (PL) intensity. We found that strong carrier localization in indium clustering induces the increases of the activation energy of PL integrated intensity, the temperature independence of PL decay profiles, and the intensity fluctuation of the cathodoluminescence images. All these observations suggest structurally and optically that the improved emission properties in the InGaN/GaN multiple quantum well with high indium composition are associated with the localized states in the strain-induced indium cluster.