Single crystal ZnO nanowires diffused with europium (Eu) from a solid source at 900 degrees C for 1 h or doped with Eu during growth have been characterized. The ZnO nanowires were grown by chemical vapor deposition on Si substrates employing Au as a catalyst. The diameter of the resulting nanowires was similar to 200 nm with a length of 1 mu m. Photoluminescence spectra excited by a He-Cd laser at room temperature showed the green luminescence at 515 nm in Eu-diffused nanowires. A small red shift of near-band-edge emission of ZnO nanowires was observed in the diffused wires, but sharp emission from Eu-3 ions was not present. Transmission electron microscopy shows crystalline Eu2O3 formation on the diffused nanowire surface, which forms a coaxial heterostructure system. When Eu was incorporated during the nanowire growth, the sharp D-5(0)-F-7(2) transition of the Eu3+ ion at around 615 nm was observed. (C) 2009 Elsevier B.V. All rights reserved.