Surface Texture and Structure of ZnO Films Synthesized by Off-Axis Sputtering Deposition
Morphology and structure of ZnO films deposited on (0001) sapphire and glass substrates by off-axis sputtering are investigated at various temperatures and pressures. All films show highly textured structures on glass substrates and epitaxial growth on sapphire substrates. The full width at half maximum of theta rocking curves for epitaxial films is less than 0.5 degrees. In textured films, it rises to several degrees. The trend of surface textures in films grown at low pressures is similar to those grown at high temperatures. A morphology transition from large well-defined hexagonal grains to flat surface was observed at a pressure of 50 mtorr and temperature of 550 C. The experiment results are explained by the transport behavior of depositing species.