Evolution mechanism of InGaN quantum dots and their optical properties

InGaN self-assembled quantum dots (QDs) have been grown by metal-organic chemical vapor deposition. The surface morphologies of InGaN QDs were investigated for different number of periods in the range of one to five. Interfacial formation mechanism of InGaN QDs was investigated by phase separation theory and different strain in active zone. In-rich localized states and interfacial atomic images were observed by spherical aberration corrected transmission electron microscopy. Furthermore, the formation mechanism of InGaN QDs was discussed according to growth kinetics of indium (In) atom migration. The optical properties of QDs-like were tested by temperature-dependent photoluminescence. These results show internal quantum efficiency increases with increasing periodicity owing to increasing total accumulated strain. QDs are formed spontaneously owing to indium composition fluctuations in InGaN layer. The variations of peak energy with increasing temperature are explained by carrier dynamics as a result of size inhomogeneity and carrier localization in InGaN/GaN active zone. These results provide experimental data and theoretical basis for fabricating high quality InGaN QDs.