Enhanced luminescence in InGaN multiple quantum wells with quaternary AlInGaN barriers

We report on the comparative photoluminescence studies of AlGaN/GaN, GaN/InGaN, and AlInGaN/InGaN multiple quantum well (MQW) structures. The study clearly shows the improvement in materials quality with the introduction of indium. Our results point out the localized state emission mechanism for GaN/InGaN structures and the quantum well emission mechanism for AlInGaN/InGaN structures. The introduction of indium is the dominant factor responsible for the observed differences in the photoluminescence spectra of these MQW structures.