Dielectric tunable characteristics of compositional-gradient BaTi1−xSnxO3 thin films

Compositional-gradient [Formula: see text][Formula: see text]O3 thin films on Pt(100)/Ti/SiO2/Si substrates are fabricated with sol–gel using spin coating. All of the structures of the prepared thin films are of single-phase crystalline perovskite with a dense and crack-free surface morphology. BTS10/15/20 thin film exhibits enhanced temperature stability in its dielectric behavior. The temperature coefficient of capacitance [Formula: see text] in the temperature range from [Formula: see text]C to [Formula: see text]C is [Formula: see text]C and that of [Formula: see text] in the temperature range from [Formula: see text]C to [Formula: see text]C is [Formula: see text]C. Furthermore, the thin films show low leakage current density and dielectric loss. High and stable dielectric tunable performances are found in BTS10/15/20 thin films: the dielectric tunability of the thin films is around 20.1% under a bias voltage of 8 V at 1 MHz and the corresponding dielectric constant is in the range between 89 and 111, which is beneficial for impedance matching in circuits. Dielectric tunability can be obtained under a low tuning voltage, which helps ensure safety. The simulated resonant frequency of the compositional-gradient BTS thin films depends on the bias electric field, showing compositional-gradient BTS thin films could be used in electrically tunable components and devices. These properties make compositional-gradient BTS thin films a promising candidate for dielectric tuning.

Dielectric Tunability Properties in (110)-Oriented Epitaxial 0.5Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 Thin Films Prepared by PLD Method

Epitaxial 0.5Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)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.