Coupling behaviors of large lattice mismatch interfaces between hexagonal ZnO and cubic (001)MgO

The combination of materials with large lattice mismatch due to different phase structures plays a significant role on designing devices. Precise control of heteroepitaxial thin films is still a big challenge because of the ambiguous understanding of the interfacial coupling behaviors. Here, by combing of molecular beam epitaxy and X-ray reflection diffraction techniques, as well as the density function theory method, we investigate the mechanisms of large mismatch interface coupling behaviors by taking ZnO film heteroepitaxial on cubic MgO(001) substrate. The X-ray reflection diffraction pole figures show a two- and four-fold rotations for the c- and m-plane ZnO films respectively. The density function theory calculations show the interface energy of c-plane ZnO is larger than that of the m-plane, and the interface azimuthal registry is determined by the interaction energy between epitaxy layers and substrates. Moreover, the evolution of the density of states crossover the interfaces shows a large band bending at the polar interface due to the internal spontaneous field.