Chemical composition fluctuations and strain relaxation in InGaN nanowires: The role of the metal/nitrogen flux ratio

The chemical composition fluctuations of InGaN nanowires are studied by a combination of Energy Dispersive X-ray spectroscopy and photoluminescence spectroscopy. It is demonstrated that these fluctuations are linked to the elastic strain relaxation mechanism affecting InGaN sections grown on GaN nanowires. It is further shown that the elastic strain relaxation mechanism depends itself on the growth conditions, in particular on the effective metal/active nitrogen flux ratio. As a consequence of the presence of chemical composition fluctuations, wide photoluminescence spectra are observed, associated with a marked carrier localization.