InxGa1-xN/GaN quantum well (QW) structures grown on c-plane surfaces for long wavelength light emitters have been investigated intended. We reached indium concentrations of x(ln), >= 0.35 with good optical and structural quality. For QW thicknesses d(QW) <= 2 nm a fully strained layer structure is observed. QWs of such high indium concentrations, however, are very sensitive to the growth conditions of the subsequent layers and thermal stability/degradation becomes an important issue. We modified the growth of the QWs to avoid or minimize V-pit formation without temperature ramping in the barriers and showed that their properties were unchanged when used in the active zone of a laser structure. (C) 2010 Elsevier B.V. All rights reserved.