Preparation And Characterization Of PSTT Ferroelectric Thin Films

Lead scandium tantalite Pb(Sc1/2Ta1/2)O3(PST) is a kind of the typical composite perovskite structure materials. Compared to other materials, PST ferroelectric thin films possess superior properties such as high pyroelectric coefficientλ, high resistivityρand big figures of merit of pyroelectric material detector FD. Though it has excellent ferroelectric and pyroelectric properties, however, PST with dense perovskite structure and good properties can only be synthesized and prepared under quite high temperature (1500℃), and due to its low Curie point (approximately -5~25℃) , the applications of PST had been substantially limited. If lead titanate (PT, its Currie temperature of about 490℃) is added into PST materials to form (1-x)PST-xPT solid solution with composite perovskite structure, it can significantly improve Currie temperature of PST material system, reduce its preparation temperature, and thus extend applications of PST material system.In the paper, the common electronic ceramics method was employed to prepare pure perovskite PSTT target and RF magnetron sputtering method was employed to prepare PSTT ferroelectric thin films. Then effects of processing parameters such as different substrates, substrate temperature, annealing temperature and annealing method on the properties of PSTT thin films were studied. At the same time, PZT80 and PZT20 targets were also prepared, and the alternate multiplayer films of PZT80 and PZT20 were partially studied. The major conclusions are as follows:1. PSTT thin films deposited on LSCO/Pt/Ti/SiO2/Si show the pure perovskite phase and rather dense. Under atmospheric conditions, PSTT thin film samples annealed at 700℃and 750℃for 2min by using rapid thermol annealing, show (220) high orientation.2. PSTT thin film samples annealed at 725℃for 3min, by using rapid thermol annealing have remanent polarization Pr of 2.12μC/cm2 and coercive field Ec of 59.35 kV/cm, permittivity of 492 and dielectric dissipation of 0.0046.3. PSTT thin film samples annealed at 700℃for 3min have leak current density less than 10-6A/cm2 at bias voltage of 15V; PSTT thin film samples annealed at 725℃for 3min have leak current density close to 10-6A/cm2 at bias voltage of 13V.4. In the frequency region from 0.5~150 kHz, the permittivity dielectric and dissipation of PZT multilayer films with dR/dT of 1:3 are 328 and 0.0098 respectively; and its the remanent polarization Pr is 32.6μC/cm2.