Through a simple hydrothermal method, well-aligned and periodic honeycomb-like ZnO nanorod arrays were fabricated on a c-plane sapphire with an aluminum-doped ZnO (AZO) seed layer. Vertical and highly ordered ZnO nanostructures with the <0002> orientation were synthesized by employing a self assembled monolayer of polystyrene (PS) microspheres as a mask. The optimal growth conditions allowed the growth of only one rod in the confined space between the microspheres. A 4) phi-scan exhibited six-fold symmetry, which indicates a favorable epitaxial relationship between the ZnO nanorods, seed layer, and c-plane sapphire substrate. The epitaxial relation is as follows: [0001](zno) parallel to[0001](Azo) parallel to[0001](c-planesapphire)" These results indicate that the AZO seed layer acts as a buffer layer that can relax the strain between ZnO and c-plane sapphire generated by the large lattice mismatch of 18%. The size of the resulting ZnO nanorods of diameter 20-90nm could be tuned by varying the concentration of the solution, pH, and duration of reaction. The large aspect ratio of the ZnO nanorod arrays can serve as a template for high surface-area applications. (C) 2017 Elsevier B.V. All rights reserved.