Physical and optical properties of sputtered lithium niobate thin films

LiNbO ₃ thin films were deposited by rf magnetron sputtering using LiNbO ₃ ceramic targets on z-cut single crystal LiTaO ₃ substrate. The as-deposited thin films were annealed at 550 degrees Celsius to 650 degrees Celsius for 60 min in oxygen ambient. The results of x-ray diffraction indicate that the dominant orientation of the sputtered LiNbO ₃ thin film is (202). The transmittance spectra of LiNbO ₃ thin films annealed at different temperatures were measured and compared with that of bulk single crystal substrate (the measured wavelength range is from 300 nm to 800 nm). The transmittance drops down to about 10% at 300 nm wavelength and has a value of 70 to approximately 80% at 800 nm wavelength.