Ferroelectricity and Electric Conduction Characteristics of Sr-Modified Lead Zirconate Titanate Thin Film Capacitors

Ferroelectric (Pb0.9Sr0.1)(Zr0.53Ti0.47)O3 (PSZT) thin film capacitors were prepared on Si substrates with a platinum-electrode coated on the underside by a sol–gel method. X-ray diffraction patterns showed that PSZT thin films were polycrystalline and the peaks of perovskite structure appeared uniquely in films annealed above 650°C. Ferroelectricity and electric conduction characteristics were observed by measuring the frequency dependent dielectric constant (ε ′–f), the capacitance versus voltage (C–V), the ferroelectric hysteresis (D–E) loops, and the leakage current density versus field (J–E). The remanent polarization and the coercive field using a sinusoidal voltage of 1 kHz and 10 V were approximately 21 µC/cm2 and 67 kV/cm, respectively. The ohmic conduction and space-charge-limited current conduction were the dominant charge transport mechanisms in sol–gel deposited PSZT films. The resistivity of PSZT films in ohmic conduction region was 4×108 Ωcm and the density of traps was about 6.5×1019 cm-3. The drift mobility at room temperature was about 86 cm2/Vs for a 240-nm-thick film and 42 cm2/Vs for a 400-nm-thick film.