Low dielectric loss Ba0.6Sr0.4TiO3/MgTiO3 composite thin films prepared by a sol-gel process

The dielectric properties of Ba0.6Sr0.4TiO3 (BST)/MgTiO3 (MT) composite thin films deposited on Pt(1 1 1)/Ti/SiO2/Si(1 0 0) substrates by the sol-gel method were investigated. The X-ray pattern analysis indicates that the thin films exhibit good crystalline quality with perovskite phase and that insertion of MT layer does not obviously affect the phase structure of BST thin films. The characterization of dielectric properties demonstrates that configuration of BST/MT/BST thin films is an effective approach to obtain low dielectric loss and dielectric tunability of BST thin films. At room temperature, the tunability of pure BST60 films and BST/MT (15 nm)/BST composite thin films is 47% and 36%, respectively, at the frequency of 1 MHz with an applied electric field of 400 kV/cm. For BST/MT/BST composite thin films, considerable reduction in the dielectric loss values is observed, which renders them attractive for tunable microwave device applications.