Semiconducting epitaxial films of metastable SrRu0.5Sn0.5O3 grown by pulsed laser deposition

Synthesis of the perovskite solid solution that forms between metallic ${\mathrm{SrRuO}}_{\mathrm{3}}$ and insulating ${\mathrm{SrSnO}}_{\mathrm{3}}$ is reported. This material is proposed as a conducting thin-film electrode/epitaxial-substrate material. While the bulk solid solution could not be formed, thin films of single-phase ${\mathrm{SrRu}}_{\mathrm{0.5}}{\mathrm{Sn}}_{\mathrm{0.5}}{\mathrm{O}}_{\mathrm{3}}$ were grown on (001) ${\mathrm{KTaO}}_{\mathrm{3}}$ single-crystal substrates by pulsed laser deposition. These films exhibit a commensurate in-plane lattice match with ${\mathrm{KTaO}}_{\mathrm{3}}$ ($a$ =3.989 Å); accordingly, the lattice constant of ${\mathrm{SrRu}}_{\mathrm{0.5}}{\mathrm{Sn}}_{\mathrm{0.5}}{\mathrm{O}}_{\mathrm{3}}$ is larger than that of commonly used conducting-oxide thin-film electrodes (e.g., ${\mathrm{SrRuO}}_{\mathrm{3}}\mathrm{,}$ ${\mathrm{LaNiO}}_{\mathrm{3}}\mathrm{,}$ and ${\mathrm{YBa}}_{\mathrm{2}}{\mathrm{Cu}}_{\mathrm{3}}{\mathrm{O}}_{\mathrm{7-\delta }}\mathrm{).}$ The ${\mathrm{SrRu}}_{\mathrm{0.5}}{\mathrm{Sn}}_{\mathrm{0.5}}{\mathrm{O}}_{\mathrm{3}}$ films were analyzed using x-ray diffraction, Rutherford backscattering, atomic force microscopy, $Z$ -contrast transmission electron microscopy, and Hall effect measurements. The results revealed excellent atomic-scale structural properties, flat surfaces (13 Å rms roughness), and $\mathrm{p-}$ type conduction with a room-temperature resistivity of 16 mΩ cm.