Dielectric properties and abnormal C-V characteristics of Ba₀.₅Sr₀.₅TiO₃-Bi₁.₅ZnNb₁.₅O₇ composite thin films grown on MgO (001) substrates by pulsed laser deposition

Abstract

Highly c-axis oriented Ba[sub 0.5]Sr[sub 0.5]TiO₃-based composite thin films were grown on MgO (001) single-crystal substrates by pulsed laser deposition and the in-plane dielectric properties of the films evaluated. X-ray diffraction characterization revealed a good crystallinity. The dielectric constant and loss were found to be 200 and 0.001-0.007 at room temperature, respectively. The butterfly-shaped C-V characteristic curve evidenced an enhanced in-plane dielectric tunability of >90% in the films at 1 MHz under a dc bias field of 0.8 MV/cm. A brief discussion is given on the abnormal C-V curves. Various tunable microwave applications of Ba[sub 0.5]Sr[sub 0.5]TiO₃-Bi[sub 1.5]ZnNb[sub 1.5]O[sub 7] composite thin films are expected.