Star-shaped ZnO nanostructures were grown over Au-coated Si (100) substrate by a cyclic feeding chemical vapor deposition method. Transmission electron microscopy image and selected area electron diffraction pattern showed that these nanostructures were single crystalline with wurtzite hexagonal structure and preferentially oriented in the c-axis direction. Photoluminescence (PL) spectra of the as-grown structures measured at room temperature showed a suppressed UV emission at 380 nm and a strong and broad green emission at 520 nm, but showed reversibly a drastic change in the PL intensity when the samples were annealed in an oxygen atmosphere at 500 degrees C. (c) 2005 Elsevier B.V. All rights reserved.