GaAs/InxGa1-xAs/GaAs hetero structures nanowires were grown by metal-organic vapor-phase epitaxy on (I I I)B GaAs substrate using the vapor-liquid-solid growth mode. The diameter of the nanowires was defined by monodisperse gold nanoparticles deposited on the GaAs substrate. High-resolution electron transmission microscopy investigation revealed the structural properties of the grown whiskers using bright field images. Using energy disperse X-ray spectroscopy measurements, the composition along and perpendicular to the vertical growth direction has been determined. In addition, the sharpness of the created heterojunctions was investigated. Finally, micro photoluminescence measurements on single GaAs/InGaAs/GaAs whiskers were carried out. (c) 2006 Elsevier B.V. All rights reserved.