Preparation of Ba₂NaNb₅O₁₅ thin films by electron cyclotron resonance plasma sputter method and their properties

Ba-Na-Nb-O thin films were formed on sapphire (1120) substrates by electron cyclotron resonance plasma sputtering by using ring shaped targets. A Ba₂NaNb₅O₁₅ (BNN) thin film of single phase was obtained, at the substrate temperature of 873 K by using the target composition of Ba:Na:Nb = 1.0:1.0:5.0. The (001) oriented BNN film was successfully obtained at 923 K. The contents of Ba and Nb in the films were independent of substrate temperature in the range between 298 K and 923 K. However, Na content decreased with increasing substrate temperature. Deposition rates of the BNN thin films were estimated to be about 1.0X10^-1 nm/s. The absorption edge of the BNN films deposited at 923 K became clear in the vacinity of 300 nm. The transmittance in the wavelength between 700 and 2000 nm have exceedingly by more than 80 %. The refractive index of the film was estimated about 2.07 at 627 nm.