ZnO thin films were deposited on glass substrates by direct current (DC) sputtering technique at room temperature (RT) to 400 degrees C with a 99.999% pure ZnO target. Then the samples deposited at RT were annealed in air from the RT to 400 degrees C. The effects of substrate temperature (T-s) and annealing treatment (T-a) on the crystallization behavior and the morphology have been studied by X-ray diffraction and atomic force microscopy. We also compared the structural properties of samples deposited at 400 degrees C on glass to those deposited on Pt/silicon substrate. The resistivity, surface roughness and size of the grains have also been studied and correlated to the thickness of ZnO films deposited on Pt/Si substrates. The experimental results reveal that the substrate has a major influence on the structural and morphological properties. For the films deposited on glass, below 400 degrees C, T-s and T-a have a similar influence on the structure of the films. Moreover, the ZnO samples deposited at RT and annealed in air have poor electrical properties. (C) 2011 Elsevier B.V. All rights reserved.