Lead-free BNT-BKT-BT thin films by pulsed laser deposition process

We have studied the effect of deposition parameters on the microstructure and ferroelectric properties of pulsed laser deposited 0.88(Bi_0.5Na_0.5)TiO₃-0.08(Bi_0.5K_0.5)TiO₃-0.04BaTiO₃ thin films on SrRuO3 coated SrTiO3 substrates. The films were deposited at different repletion rates, substrate temperatures, and laser energies. It has been demonstrated that the film made at 800 °C, 10 Hz, 400 mtorr and 1.2 J.cm^-2 shows the best ferroelectric properties among the investigated films. The remnant polarization for this film was measured to be about 30 μC.cm^-2. We have also discussed the electrical conduction mechanisms in the temperature range of 200-350 K. At low electric fields, the leakage mechanism is governed by the ohmic conduction. With increasing the applied filed, an abrupt increase in the leakage current was observed. This was attributed to a trap-filling process by the injected carries. At sufficiently high electric fields, the leakage current obeyed the Child´s trap-free square law suggesting the space charge limited current was the dominant mechanism.