Improvement of Dielectric Properties of Graded Co-Doped (Ba0.7Sr0.3) TiO3 Thin Films Fabricated by Sol–Gel Method

Abstract

The undoped, homogeneous and graded Co-doped (Ba0.7Sr0.3) TiO3 (BST) thin films with compositionally gradient from 0 mol% to 5 mol% were prepared on Pt /Ti /SiO2/Si (100) substrates by sol–gel technique. All of the thin films crystallized into a pure perovskite structure after post-deposition annealing. Dielectric properties of undoped, homogeneous and graded Co-doped BST thin films were investigated as a function of frequency and direct current bias field. These results showed that the graded acceptor doping was a promising technique to reduce the loss tangent and leakage current while maintaining weak change in tunability of BST thin film.