Highly arrayed ZnO nanorods were fabricated on the Si substrate buffered with patterned ZnO film (ZnOf/Si) via wet-chemical process. The growth behavior and morphology of single-crystal ZnO nanorods (ZNs) were investigated in terms of the annealing temperatures of the sputtered ZnO film. We found that the growth morphology of ZnO nanorods is strongly dominated by the grain size of the ZnO film on the Si substrate. The ZnOf/Si substrate was annealed at above a critical temperature to promote the crystallization of ZnO phase, and high-resolution transmission electron microscopy demonstrated that both ZNs and ZnOf on Si substrate are coherent. Furthermore, the ZNs seem to nucleate from the concave tip near the grain boundary between two ZnO grains in the ZnO film because of higher surface energy. However, a higher annealing temperature may lead to the formation of a larger ZnO crystal due to the coplanar coalescence behavior of several individual ZnO nanorods. (c) 2006 American Vacuum Society.