Orientation Dependence of Epitaxial and One-Axis-Oriented (Ba0.5Sr0.5)TiO3 Films Prepared by RF Magnetron Sputtering

The dependences of electrical properties on (111) and (100) orientations were investigated for (Ba0.5Sr0.5)TiO3 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)cSrRuO3∥(100)SrTiO3 and (111)cSrRuO3∥(111)SrTiO3 substrates, while one-axis-oriented films were grown on (100) c SrRuO3/(100)cLaNiO3/(111)Pt/TiO2/SiO2/Al2O3 and (111) c SrRuO3/(111)Pt/TiO2/SiO2/Al2O3 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.