Influence of growth conditions on morphology of ZnO nanostructures in CVD process

The effects of growth conditions on the morphology of ZnO nanostructures grown by CVD process with Au catalyst were systemically studied and the key factors controlling growth were identified. Two growth modes of ZnO formation were observed: self-catalyzed growth on Si substrate and gas-phase nucleation and growth. In the former case, the ZnO nanostructures grow by the vapor-solid mechanism and the morphology is very sensitive to the growth conditions. The partial pressure of zinc vapor determines the prevailing growth morphology. On the other hand, for the second mode, tetragonal nanowires are nucleated and their length increase with growth temperature.