Oriented ZnO nanorod arrays and ZnO thin films were simultaneously grown on magnetron sputtered ZnO seed layers through a hydrothermal approach without any metal catalyst. The c-oriented ZnO nanorod arrays were grown on the unannealed ultrathin ZnO seed layer, while the ZnO thin films with (1 0 0) preferred orientation were grown on the annealed ultrathin ZnO seed layer. Thermodynamically preferred (0 0 2) oriented grain growth will be suppressed by the morphology changes of the ultrathin seed layer while the (1 0 0) orientation will preferentially develop instead. Photoluminescence spectroscopy results show that the UV emission peak shifts slightly to shorter wavelength with increasing the annealing temperature of the ultrathin ZnO seed layer. (C) 2009 Elsevier B.V. All rights reserved.