Optimizing the growth process of the active zone in GaN based laser structures for the long wavelength region

InxGa1−xN/GaN quantum well (QW) structures grown on c-plane surfaces for long wavelength laser structures have been investigated. We found that temperature ramping in the barriers improves the layer structure in avoiding V-pit formation and improves the homogeneity of indium incorporation. In choosing proper temperature profiles degradation of the QWs can be avoided. We demonstrate optical gain for wavelengths larger than 500nm using structures with an active zone grown in such way. ► InGaN/GaN quantum wells with high indium content for long wavelength laser structures. ► Homogeneous indium incorporation is critical. ► Optical gain in green reached. ► Indium not easily incorporated beyond 25%.