Various Shapes of ZnO and CdO Nanostructures Grown by Atmospheric-Pressure Chemical Vapor Deposition

Various shapes of ZnO and CdO nanostructures were successfully grown on a-and c-plane sapphire substrates coated with Au nanocolloidal solution by atmospheric-pressure chemical vapor deposition methods under a simultaneous source supply of metal powder (Zn or Cd) and H2O. The ZnO and CdO nanorods (NRs) grown at higher substrate temperatures (T(S)s) exhibited tapered shapes, resulting from the competition between the axial growth due to the vapor-liquid-solid (VLS) mechanism and the radial growth due to the vapor-solid (VS) mechanism. The alternate source supply of Zn and H2O was found to be effective for suppressing the tapering of ZnO NRs. The appearance of the Y- and T-shaped nanotrees of CdO may be due to the splitting and migration of catalytic particles during the growth process. These results suggest that both the source supply sequence and the substrate temperature are important factors for the shape design of oxide nanostructures. (C) 2011 The Japan Society of Applied Physics