Shape-controlled ZnO nanostructures (nanorods, nanotips, nanonails, nanowires, nanoropes and nanolawns) were synthesized by metalorganic chemical vapor deposition at relatively low growth temperature (400-500 degrees C) via assistance of colloidal gold (An) nanoparticles dispersed on SO2/Si substrates. The shape variation of the nanostructures was sensitive to the density of the An nanoparticles on substrates as well as the growth temperature, allowing the effective shape control of the nanostructures by handling those parameters. The grown ZnO nanostructures were found to have negligibly weak deep-level emission, as evidenced by photoluminescence (PL) measurements. The strong PL emission band, which originate from free-excitons in shape-controlled ZnO nanostructures indicates that the shaped-controlled ZnO nanostructures by this method have high optical quality. (c) 2006 Elsevier B.V. All rights reserved.