Effect of thickness on the dielectric properties of bismuth magnesium niobium thin films deposited by rf magnetron sputtering

The Bi1.5MgNb1.5O7 (BMN) thin films with cubic pyrochlore structure were prepared on Au-coated Si (001) substrates by rf magnetron sputtering. Effects of thin film thickness on the structure and dielectric properties of BMN thin films were investigated. As the thickness increases, the permittivity increases, the dielectric loss and leakage current decreases, and the tunability has an obvious improvement. The 300 nm thick BMN thin films annealed at 750 °C exhibit dielectric constant of 93, low dielectric loss of 0.00224 at 1 MHz, and maximum tunability of 33.01% at the bias field of 1.25 MV/cm. The relationship of leakage current and thickness was also studied and a possible explanation was proposed. The excellent dielectric properties make BMN thin films promising for potential tunable capacitor applications.