Synthesis and dielectric properties of (Ba,Ca)(Zr,Ti)O3 thin films using metal-organic precursor solutions

Perovskite (Ba,Ca)(Zr,Ti)O3 (BCZT) is a representative dielectric material for capacitors and its properties can be controlled by varying the Zr/Ti ratio and substituting Ca for the Ba site. In this study, Ba(Zr,Ti)O3 (BZT) and BCZT thin films were synthesized by chemical solution deposition. Perovskite BZT and BCZT thin films were fabricated on Pt/TiOx/SiO2/Si substrates at temperatures above 650 °C. Among the BZT thin films with different Zr/Ti ratios, BZT (Zr:Ti = 0.20:0.80) thin films exhibited homogeneous and smooth surface morphologies and excellent dielectric properties. The dielectric constant of the BZT (Zr:Ti = 20:80) thin film was approximately 900, with a dielectric loss tangent of less than 5% at room temperature. Furthermore, the Ca-doped BZT (Ba:Ca = 0.95:0.05, Zr:Ti = 0.20:0.80) thin films had a larger dielectric constant than a BZT (Zr:Ti = 0.20:0.80) film without Ca, lower dependence of the dielectric constant on temperature and lower dielectric loss over a wide range of temperatures.