Characterization and dielectric properties of (SrTiO3/BaTiO3)n multilayer thin films deposited on Pt/Ti/SiO2/Si substrates by double rf magnetron sputtering

The dielectric properties of SrTiO3/BaTiO3 multilayer thin films ((ST/BT)n) prepared by double target rf magnetron sputtering have been characterized as a function of thickness, frequency and applied voltage. The XRD pattern shows the formation of the (ST/BT)4 multilayers with designated modulation. The lattice strain increases from 0.30 to 1.2% when the layers number (n) increases from 1 to 4. The dielectric constant increases with increasing layer number. The remanent polarization (Pr) and coercive field (Ec) are 3 and 7 μC/cm2, and 20 and 60 kV/cm, respectively, for the (ST/BT)2 and (ST/BT)4 multilayers. The result shows that the (ST/BT)n multilayers exhibit ferroelectricity and have an increased Ec, and decreased Pr, as compared with the bulk material.