Preparation of c-axis Oriented Ba₂NaNb₅O₁₅ Thin Films on Sapphire (012) Substrate and their Properties

Abstract

Ba₂NaNb₅₁₅ (BNN) thin films were formed on sapphire (012) substrates by electron cyclotron resonance plasma sputtering by using ring shaped targets. BNN thin films of single phase were obtained at the substrate temperature in the range between 773 and 923 K by using the target composition of Ba : Na : Nb = 1.2: 1.2 : 5.0. The (001) oriented BNN films were successfully obtained at 773 and 923 K. The contents of Ba, Na and Nb in the films were independent of substrate temperature in the range between 773 and 923 K. Deposition rates of the BNN thin films were estimated to be about 8.3×10^-2 nm/s. The absorption edge of the BNN films became clear in the vicinity of 300 nm. The transmittance in the wavelength between 400 and 2500 nm have exceedingly by more than 80 %. The refractive indices of the films were estimated between 1.7 and 3.0. The dielectric constants of the BNN films were about 10.