Microstructure of BaRuO3 thin films grown on (001) SrTiO3

BaRuO 3 thin films with hexagonal 4H structure were grown on (001) SrTiO3 by a 90° off-axis rf-sputtering technique. The thin films were epitaxially grown on the (001) surface of SrTiO3, with (202̄3) planes parallel to the surface of the substrate. Within the growth plane, the film consists of four different crystallographic orientations with respect to the substrate, defined by the surface symmetry of the (001) SrTiO3 substrate. BaRuO3 grains of all four orientations show an anisotropic shape elongated along the [1̄21̄0] direction. The reason for the anisotropic growth is that the lattice mismatch between BaRuO3 and SrTiO3 is smaller along the [1̄21̄0] direction of SrTiO3 in comparison to that along its perpendicular direction. Stacking faults and intergrowths of the 9R structure were observed in small local regions of the film.