ZnO crystals formed on sapphire (11 (2) over bar0) substrates by means of side-flow-type metallorganic chemical vapor deposition (MOCVD) are controlled to various shapes by adjusting process parameters. The relationship between the morphology and the crystallinity of ZnO crystals is investigated. It is found that the crystallinity of a ZnO film structure with nanostructures is better than that of only a ZnO nanorod structure although they are fabricated under the same growth temperature condition. In the case of a ZnO nanorod structure, a high growth temperature (at or over 1073 K) plays a significant role in improving ZnO crystallinity. It is also confirmed by X-ray diffraction rocking curves and transmission electron microscopy observations that ZnO crystals with a microcone morphology formed at 1073 K have high crystal quality. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3121225] All rights reserved.