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 inplane 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)SrRUO3//(100)SrTiO3 and (111)(c)SrRUO3// (111)SrTiO3 substrates, while one-axis-oriented films were grown on (100)(c)SrRuO3/(100)(c)LaNiO3/(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, epsilon 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 epsilon(r) and tunability on orientation were existed, irrespective of the in-plane orientation and the thermal strain caused in the film by the substrates.