Self-organized comb-like ZnO microstructures: Morphologies and defect induced optical emission

Comb-like ZnO microstructures have been synthesized in high yield via catalyst free thermal evaporation at a relatively low temperature. The structural and optical properties of the prepared samples were studied using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectrum, photoluminescence (PL) and microscopic PL images. The morphologies of the products show a ribbon like stem and nanorod arrays with square, rectangle and parallelogram cross section aligned along one side of the former. PL spectra and microscopic PL images reveal that the prepared microstructures have strong orange-yellow emission, notably different from the green emission of ZnO nanocombs by only thermally evaporating pure zinc power. The difference of optical emission could be ascribed to the change of defect status resulted from impurity effect during the growth of ZnO microstructures. (C) 2009 Elsevier B.V. All rights reserved.