Effects of CeO2 buffer layer on the dielectric properties of Ba0.6Sr0.4TiO3 thin films prepared by sol–gel processing

The Ba 0.6 Sr 0.4 TiO 3 (BST60) thin films were deposited on Pt(111)/Ti/SiO 2 /Si(100) substrates by a sol–gel method. The thickness of CeO 2 , serving as a buffer layer, was varied from 0 to 75 nm, in order to optimize the dielectric tunable property. X-ray patterns analysis indicates that all the thin films exhibit good crystalline quality with a pure perovskite phase and insertion of the CeO 2 buffer layer does not change the crystal structure of BST60. Dielectric properties of the thin films were investigated as a function of both temperature and direct current electric field. The results show that dielectric constant and loss are modified by insertion of the CeO 2 buffer layer. The BST60 thin films with 25 nm thickness CeO 2 buffer layer have the highest figure of merit, low dielectric loss, and suitable dielectric constant, which render them attractive for the tunable microwave device applications.