Non polar in plane AIN films were grown epitaxially on bare and ZnO buffered m-plane sapphire by laser molecular beam epitaxy. Based on X-ray theta-20 and,phi scanning results, the in-plane epitaxial relationships of AIN/sapphire and AIN/ZnO/sapphire are [00011](AIN)parallel to [11 (2) over bar0](sapphire) and [0001](AIN) parallel to [0001](ZnO) parallel to [11 (2) over bar0](sapphire), respectively. A direct epitaxy without in-plane rotation is observed between AIN and ZnO, due to a small lattice mismatch, which results in a higher bond areal density of AIN/ZnO/sapphire than that of AIN/sapphire. ZnO butter layer transforms the in-plane residual strain from compressive strain to tensile strain along the direction of [0001](AIN), owing to the change in the in-plane lattice mismatch. X-ray rocking curve and atomic force microscope reveal that ZnO butler layer can change the mosaicity spread along the direction of [0001](AIN) and [11 (2) over bar0](AIN) leading to the opposite striated anisotropic morphology of AIN/sapphire and AIN/ZnO/sapphire. The decrease in anisotropic characteristic of AIN/ ZnO/sapphire is consistent with the result of in-plane lattice mismatch. (C) 2014 Elsevier B.V. All rights reserved.