Ferroelectric Properties of Transparent KTN Thin Film Produced by Pulsed Laser Deposition

Using the Sol-Gel method for producing the KTN ultrafine powder and the sintering technique with K2O atmosphere to prepare KTN ceramics as the targets instead of the KTN single crystal, highly oriented KTN thin films were produced on the transparent single crystal quartz (100) by the pulsed laser deposition (PLD). The XRD analysis indicates that the perovskite structure with (h00) orientation is the major phase (>98%) in KTN. The Current-Voltage characteristics were found to be Ohmic at low fields and space-charge-limited at higher fields. This phenomenon is reasonably explained by SCLC theory. The leakage current was lower than 250 μA/mm2 at 0-5 V, which shows the film has good ferroelectric performances. The frequency dependence of dielectric constant results demonstrates that the dispersion of electric capacity is large at low frequency but small at high frequency. The dielectric constant was 12600 at frequency of 10 kHz. The P~E hysteresis loop shows that the remanent polarization and the coercive field are 9.25 μC/cm2 and 7.32 kV/cm, respectively. The SEM results shows that the surfaces are homogeneous, smooth, crack-free and dense. The refractive index was 1.776 at incident wave length 1.2 μm, the thickness 968 nm, and the growth rate 0.027 nm per pulse.