| Summary: | For this study, polarity-controlled ZnO films were grown on lithium niobate (LiNbO<sub>3</sub>) substrates without buffer layers using the pulsed-laser deposition technique. The interfacial structure between the ZnO films and the LiNbO<sub>3</sub> was inspected using high-resolution transmission electron microscopy (HR-TEM) measurements, and X-ray diffraction (XRD) measurements were performed to support these HR-TEM results. The polarity determination of the ZnO films was investigated using piezoresponse force microscopy (PFM) and a chemical-etching analysis. It was verified from the PFM and chemical-etching analyses that the ZnO film grown on the (+z) LiNbO<sub>3</sub> was Zn-polar ZnO, while the O-polar ZnO occurred on the (-z) LiNbO<sub>3</sub>. Further, a possible mechanism of the interfacial atomic configuration between the ZnO on the (+z) LiNbO<sub>3</sub> and that on the (-z) LiNbO<sub>3</sub> was suggested. It appears that the electrostatic stability at the substrate surface determines the initial nucleation of the ZnO films, leading to the different polarities in the ZnO systems.
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