Effects of Growth Conditions on Structure and Dielectric Properties of Bismuth-Magnesium Niobate Thin Films

The Bi1.5MgNb1.5O7 (BMN) thin films were prepared on platinum coated sapphire by rf magnetron sputtering deposition. Effects of substrate temperature, sputtering ambient and post rapid thermal annealing on structure, morphologies, and dielectric properties of films were investigated. Thin films have cubic pyrochlore structure when substrate temperature at 650°C or higher. Corresponding to tunable dielectric properties of bismuth based cubic pyrochlore thin films, voltage tunability of Bi1.5MgNb1.5O7 thin films increases with substrate temperature. Bi1.5MgNb1.5O7 thin films exhibit low dielectric loss of ∼ 0.0018–0.004. A brief discussion is given on the enhanced tunability of Bi1.5MgNb1.5O7 thin films. The relatively high tunability and low dielectric loss suggest that Bi1.5MgNb1.5O7 thin films have potential application for tunable capacitor applications.