(11 (2) over bar0) oriented ZnO films where the c-axis is parallel to a substrate are good candidates for acoustic shear wave devices and sensors. Although ZnO film has tendency to develop c-axis normal (0001) orientation, unusual (11 (2) over bar0) orientation appears in the situation that energetic oxygen ions generated from a target surface bombard the substrate during film growth in a reactive sputtering. The flux and the energy of these ions depend on the transition between the metal mode and the oxide mode on the Zn metal target surface. Here, the effect of the target surface condition on the development of unusual (11 (2) over bar0) orientation is investigated. The higher crystalline (11 (2) over bar0) orientation appeared in the oxide mode, probably because a large amount of energetic oxygen ions generated by the oxidized part of the Zn target. (C) 2012 Elsevier B.V. All rights reserved.