Hierarchical ZnO nanostructures: Growth mechanisms and surface correlated photoluminescence

ZnO nanowires were grown by vapor-transport and deposition on Au nanocluster covered fused and thermal silica and c-Si. The nanowire size and density depended strongly on the substrate type. By decreasing the O 2 to local Zn partial pressure ratio, the growth pattern changed to nanocombs and nanosheets. ZnO nanohedgehogs were found on bare c-Si. We observe a remarkable correlation between the defect to exciton photoluminescence intensity ratio and the nanostructures specific surface areas. These results indicate that changes in strain and O deficiency defects at surfaces are behind the observed morphology changes, one to two-dimensional growth transition, and corresponding luminescence.