Structure and dielectric properties of Ca-doped (Ba0.7Sr0.3) TiO3 thin films fabricated by sol–gel method

A wide range of Ca-doped (Ba0.7Sr0.3)TiO3 (BST) thin films (from 0 to 20 mol%) have been prepared on Pt/Ti/SiO2/Si (100) substrates by sol–gel technique. The structural and dielectric properties of BST thin films were investigated as a function of Ca dopant concentration. The results showed that the microstructure and dielectric properties of the BST films were strongly dependent on the Ca contents. With the Ca dopant concentration increasing, the grain size, dielectric constant and dielectric loss of the BST thin films decreased. As the content of Ca dopant reaches 10 mol%, the dielectric constant, dielectric loss, tunability, the value of FOM and the leakage current density are 281, 0.0136, 16.7%, 12.3 and 5.5 × 10−6 A/cm2, respectively.