Agradecimentos: This work was partly supported by the French National Research Agency (ANR) through Carnot funding and through the Nanoscience and Nanotechnology Program (Project BONAFO no. ANR-08-NANO-031-01). Part of this work has been funded through the METSA network. We also acknowledge the technical assistance of Y Curé for operating the MBE machine Ver menos

Abstract: We demonstrate the strong influence of strain on the morphology and In content of InGaN insertions in GaN nanowires, in agreement with theoretical predictions which establish that InGaN island nucleation on GaN nanowires may be energetically favorable, depending on In content and nanowire diameter. EDX analyses reveal In inhomogeneities between the successive dots but also along the growth direction within each dot, which is attributed to compositional pulling. Nanometer-resolved cathodoluminescence on single nanowires allowed us to probe the luminescence of single dots, revealing enhanced luminescence from the high In content top part with respect to the lower In content dot base Ver menos