Polarity driven morphology of zinc oxide nanostructures

Catalyst-free ZnO nanostructures were grown by pulsed-laser deposition on c-oriented sapphire. The nanostructure morphology can be controlled by introducing a nucleation layer. Depending on the doping concentration in the nucleation layer two distinct types of nanostructures are observed. On intrinsic nucleation layers nanowires form, while Al-doping results in a honeycomb network of nanoscale walls. From scanning-electron microscopy and X-ray photoelectron spectroscopy a correlation between nanostructure morphology and the polarity of the nucleation layers is derived. (C) 2013 AIP Publishing LLC.