Seed-assisted growth of epitaxial ZnO nanorod arrays with self-organized periodicity and directional alignment

► We report a seed-assisted growth of epitaxial ZnO nanorod (NR) arrays on sapphire substrates. ► The self-organized periodic ZnO NRs can be grown on substrates without the pre-patterning processes. ► The spatial ordering of the ZnO NRs was influenced by the seed growth conditions and substrate surface. ► Post-growth annealing of the ZnO seeds changed the morphologies and alignment of the ZnO NRs.