Oxide materials with strong ionicity are associated with a large number of lattice defects because the defect formation enthalpy is very low. The control of growth mode and lattice defects in film growth of hexagonal ZnO plays an important role in producing new functional applications utilizing optical, magnetic and electrical properties. Thus far, we have investigated growth mode, optical and electrical characterizations in ZnO films in relation to polarity and non-polarity. In this report, we present a correlation between surface morphology and growth direction, and then show that optical and electrical properties were closely related to lattice defects generated in the host. Furthermore, we introduce self-organization of surface nanostructures and a local phase separation induced by interface defects in heteroepitaxial growth with lattice mismatch.