Microstructure and Electrical Conductivity of Epitaxial BaRuO<SUB>3</SUB> Thin Films Prepared on (001), (110) and (111) SrTiO<SUB>3</SUB> Substrates by Laser Ablation

Abstract

BaRuO 3 (BRO) thin films were prepared on SrTiO 3 (STO) single crystal substrate by laser ablation, and their microstructures and the anisotropy of electrical conductivity were investigated. The (205) and (104) doubly oriented BRO thin film was grown epitaxially on (001) STO substrate. Epitaxial (110) and (009) BRO thin films were obtained on (110) and (111) STO substrates, respectively, at oxygen pressure of 13 Pa and substrate temperature of 973 K. Epitaxial (205) (104) BRO thin film had a tetragonal texture whereas (110) BRO thin film showed a faceted island texture. Epitaxial (009) BRO thin films had a smooth surface due to a good lattice consistency between (009) BRO plane and (111) STO plane, and exhibited the highest electrical conductivity of 1:1 Â 10 5 SÁm À1 among the (205) (104), (110) and (009) BRO thin films.

Atomic Structure of the Initial Nucleation Layer in Hexagonal Perovskite BaRuO3 Thin Films

“…It has been reported that hexagonal perovskite thin films of various polymorph phases are grown with a smoother hexagonal terrace structure on the surface of (111) SrTiO 3 (STO) substrates compared to those on (001) or (011) STO substrates, which are found to have orthogonal textures or plate‐like islands, respectively. [ 17,18 ] While some polycrystalline hexagonal perovskite thin films have been studied using X‐ray diffraction and transmission electron microscopy (TEM), [ 19,20 ] the microstructure of the single‐phase thin film has not yet been investigated at the atomic scale, largely owing to the lack of high‐quality epitaxial thin films. The formation mechanism of the high‐quality hexagonal perovskites at the initial stage of growth on (111) cubic‐perovskite substrates would provide crucial information for stabilizing and further strain‐engineering the metastable hexagonal perovskite phases through thin‐film epitaxy.…”