Crystal Structure and Dielectric Characterization of a (SrTiO3/BaTiO3) n Multilayer Film Prepared by Radio Frequency Magnetron Sputtering

Abstract

multilayer films with Pt bottom and top electrodes have been prepared by a double target radio frequency (RF) magnetron sputtering, and their dielectric properties have been characterized as a function of temperature, frequency, bias voltage, and applied voltage. The X-ray diffraction (XRD) pattern reveals that the deposited (SrTiO 3 /BaTiO 3 ) n multilayer films have a designed modulation. The interfaces within the multilayer films appear smooth and dense without any microcracks, and the adhesion is very good. The dielectric constant of the (SrTiO 3 /BaTiO 3 ) n multilayer film increases with increasing layer number (n), and the leakage current density is less than 1 9 10 À8 AAEcm À2 for the applied voltage less than 5 V for the 450-nm-thick (SrTiO 3 /BaTiO 3 ) n multilayer films. The remanent polarization (P r ) and the coercive field (E c ) of the 350-nm-thick (SrTiO 3 /BaTiO 3 ) 4 multilayer films are 7 lCAEcm À2 and 60 kVAEcm À1 , respectively, exhibiting ferroelectricity. (SrTiO 3 /BaTiO 3 ) 4 multilayer films have a high E c and a lower P r , as compared with the bulk BaTiO 3 single crystal. The 450-nm-thick (SrTiO 3 /BaTiO 3 ) 4 multilayer films have a leakage current density-voltage characteristic, which makes them suitable for application in DRAMs capacitors.