Thin films prepared by magnetron sputtering on c-plane sapphire may exhibit a columnar growth with an average column diameter depending on the deposition temperature. In this case two epitaxial relationships coexist and adjacent columns were rotated, one from the other, by 90° around the [00•1] direction. The long range rotation between domains was in agreement with the theoretical epitaxial relationships, but the local angles oscillate between 27° and 32° due to the formation of interfaces, which settle into low energy configurations with grain boundary dislocations of a Burgers vectors and 5/7 aligned structural units for the 32.2° tilt angle.

Formation of a Low Energy Grain Boundary in ZnO - the Structural Unit Concept in Hexagonal Symmetry Materials. Ruterana, P., Abouzaid, M., Béré, A., Chen, J.: Journal of Applied Physics, 2008, 103[3], 033501