Spatial distribution of indium (In) atoms in ternary InxGa1-xAs nanowires (NWs) was investigated by the energy-dispersive X-ray spectroscopy, which were grown on Si (111) by metal-organic chemical vapor deposition. The NWs have a tapered morphology with thicker diameter and higher In composition in the bottom of NWs. However, decreasing growth temperature and Will ratio resulted in straight NWs with constant In composition throughout the NWs. This was attributed to enhanced deposition on the sidewall of the NW with higher In composition through the vapor-solid mode, leading to a core-shell structure consisting of low and high In-content layers. (C) 2013 Elsevier B.V. All rights reserved.