Dielectric Tunability Properties in (110)-Oriented Epitaxial 0.5Ba(Ti_0.8Zr_0.2)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ Thin Films...

Epitaxial 0.5Ba(Ti_0.8Zr_0.2)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ (BZT-BCT) thin films with single-crystal perovskite structure have been grown by pulsed laser deposition (PLD) on the (110) SrRuO₃/SrTiO₃ substrates. Temperature-dependent dielectric measurements show obvious characteristics of a diffused phase transition. Typical P-E hysteresis loops with a distinct ferroelectric imprint phenomenon are observed in these BZT-BCT thin films with a remnant polarization of 2.0 μC/cm² and coercive field of 187 kV/cm. Small leakage currents (<1 × 10^-6 A/cm²) are obtained in these thin films under an electrical field of 240 MV/m. These BZT-BCT thin films have shown large dielectric tunability values ranging from 75.8% to 85.7%, under a wide temperature range from 200 K to 330 K and a frequency range between 100 Hz and 100 kHz, which shows their good temperature and frequency stability. Such excellent dielectric tunability properties in these (110)-oriented BZT-BCT thin films promise their great potentials in practical phase shifter applications.