Effects of local structure on optical properties in green-yellow InGaN/GaN quantum wells

We have performed photoluminescence measurements (PL) for green-yellow InGaN/GaN multiple quantum wells (MQWs) in which InGaN layer was embedded in the barrier as a strain-controlling interlayer to verify the effect on the crystal quality and the internal electric field (F0). From the analysis of both the time-resolved PL and the excitation-power dependence of PL, it has been revealed that the PL intensities and the decay time were enhanced for the MQWs with the InGaN interlayer although the wavelength dependence of the F0 scarcely changes. This indicates that the InGaN interlayer suppresses the degradation of InGaN quantum well rather than the quantum-confinement Stark effect, suggesting that optical properties can be improved by improving the crystal quality through optimizing the local structure as well as the growth conditions. From the light-emitting diodes using the interlayer, we obtained an output power and external quantum efficiency of 10.2 mW and 23.5% at 20 mA with the wavelength of 552 nm.