Dielectric and Ferroelectric Properties of BNT-Based Thin Films by Pulsed Laser Deposition

We have studied the effect of laser repetition rate on the microstructure, crystallographic orientation, dielectric and ferroelectric properties of pulsed laser deposited 0.94(Bi0.5Na0.5)TiO3-0.04(Bi0.5K0.5)TiO3-0.02BaTiO(3) thin films on SrRuO3 coated SrTiO3 substrates. The films were deposited at different repletion rates of 2 Hz, 4 Hz and 8 Hz, while the other processing parameters such as the substrate temperature and oxygen partial pressure were kept constant. It has been demonstrated that the film made at 4 Hz has been epitaxially grown on the substrate with a smooth and flawless surface and shows the best ferroelectric properties among the investigated films. The remnant polarization and dielectric constant for this film were measured to be 13.6 mu C.cm(-2) and 425 (at 1 MHz). The leakage current density of the optimized film is 1.3 > 10(-5) A.cm(-2) at 320 kV.cm(-1), which is about 3 orders of magnitude lower than those observed in the films prepared at repetition rates of 2 Hz and 8 Hz. The remnant polarizations for the films deposited at 2 Hz and 8 Hz were found to be 8.7 mu C.cm(-2) and 7.6 mu C.cm(-2), respectively.