Orientation Dependence of Epitaxial and One-Axis-Oriented (Ba_0.5Sr_0.5)TiO₃ Films Prepared by RF Magnetron Sputtering

Abstract

The dependences of electrical properties on (111) and (100) orientations were investigated for (Ba 0.5 Sr 0.5 )TiO 3 films with in-plane random (one-axis-oriented films) and aligned orientations (epitaxial films) prepared by RF magnetron sputtering. Epitaxial films with (100) and (111) orientations were grown on (100) c SrRuO 3 ∥(100)SrTiO 3 and (111) c SrRuO 3 ∥(111)SrTiO 3 substrates, while one-axis-oriented films were grown on (100) c SrRuO 3 /(100) c LaNiO 3 /(111)Pt/TiO 2 /SiO 2 /Al 2 O 3 and (111) c SrRuO 3 /(111)Pt/TiO 2 /SiO 2 /Al 2 O 3 substrates, respectively. Films with the (111) orientation had larger relative dielectric constants, ε r , measured at an oscillation of 20 mV and 100 kHz under an applied dc bias electric field of 0 kV/cm and a larger tunability against the dc bias electric field than (100)-oriented films for both epitaxial and one-axis orientations. These data show the dependences of ε r and tunability on orientation were existed, irrespective of the in-plane orientation and the thermal strain caused in the film by the substrates.