Evolution of ZnO nano-crystals grown on a profiled sapphire(0001) substrate with Au nano-crystals

This paper reports the structural evolution of ZnO nano-crystals deposited on profiled Au/sapphire(0001) substrates by radio frequency sputtering. In contrast to the typical catalytic growth of ZnO nano-crystals with Au seeds, ZnO was initially formed as nano-discs on top of the Au nano-crystals, and their eventual shape became a replica of the cuboctahedral Au nano-crystals. The ZnO nano-discs transformed into hexagonal nano-pyramids through the intermediate morphology of sunflower typed ZnO nano-crystals. The ZnO nano-pyramids had a polar hexagonal (0001) basal plane and O2- terminated {101¯1} facets. The ZnO nano-pyramids exhibited surface acceptor-bound exciton and donor-bound exciton emissions in the photoluminescence spectra.