Lead-free ferroelectric barium titanate -based thin film for tunable microwave device application

Lead-free ferroelectric barium titanate-based (Ba 0.85 Sr 0.15 Zr 0.1 Ti 0.9 O 3 , BSZT) thin films have been successfully deposited on Pt- coated silicon substrates by a spin-coating solgel method. Microstructure and dielectric respones of the Pt/BSZT/Pt thin film capacitors were investigated in detail. X-ray diffraction analysis results indicated that BSZT thin films were well crystallized in tetragonal perovskite structure with a random crystal orientation at rather low temperature of 650 °C. Dielectric constant and dielectric loss of the thin film capacitors were performed at various bias voltage ranges and frequency from 1kHz up to 5MHz. Hysteresis C-V curves with two maxima confirmed the ferroelectric nature in the film. The BSZT capacitors provide excellent dielectric tunability ∼ 42- 69% and high figure-of-merit (FOM) ∼ 4-17 at different bias voltages.