The 30 degrees rotation domains in wurtzite ZnO films

The 30 degrees rotation domains in ZnO films were studied by transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). The cross-section and plane-view observations reveal that the 30 degrees rotation domains have elliptical cylindrical shape, with the longitude axis along one of the directions and the short axis along one of the orientations, respectively. The volume fraction of the 30 degrees rotation domains is about 1%. Due to the elliptical shape of the domain boundaries along the [0001](ZnO) direction, partially disordered superlattice-like structures are formed. As shown by the HREM images and Zn elemental mapping, these super-lattices are most likely caused by periodical segregation and depletion of Zn along the domain boundary for compensating the mismatched lattice strain. (c) 2006 Elsevier B.V. All rights reserved.