Microstructure and electrical conductivity of epitaxial CaRuO₃ thin films prepared on (001), (110) and (111) SrTiO₃ substrates by laser ablation

CaRuO₃ (CRO) thin films were prepared on SrTiO₃ (STO) single-crystal substrates by laser ablation, and their microstructures and the effect of lattice misfit on electrical conductivity were investigated. Pseudo-cubic (001), (110) and (111) oriented CRO thin films were grown epitaxially with the in-plane relationships on (001), (110) and (111) STO substrates at an oxygen pressure of 13 Pa and a substrate temperature of 973 K, respectively. Epitaxial (001) thin films showed a flat and smooth surface with a terrace and step structure whereas (110) CRO thin film had a faceted pyramid-like structure. The (111) CRO thin film had a rough terrace and step structure with trigonal texture. The lattice expansion of CRO would cause the decrease of the electrical conductivity. Epitaxial (111) CRO thin films has good lattice consistency with (111) STO substrate, and exhibited the highest electrical conductivity of 1.5 × 10⁵ S m^-1 S among the (001), (110) and (111) CRO thin films.