Heteroepitaxial growth of BaSnO3 and Ba1−xLaxSnO3 (x = 7%) lanthanum doped barium stannate thin films on different perovskite single crystal (SrTiO3 (001) and SmScO3 (110)) substrates has been achieved by pulsed laser deposition under optimized deposition conditions. X-ray diffraction measurements indicate that the films on either of these substrates are relaxed due to the large mismatch and present a high degree of crystallinity with narrow rocking curves and smooth surface morphology while analytical quantification by proton induced X-ray emission confirms the stoichiometric La transfer from a polyphasic target, producing films with measured La contents above the bulk solubility limit. The films show degenerate semiconducting behavior on both substrates, with the observed room temperature resistivities, Hall mobilities, and carrier concentrations of 4.4 mΩ cm, 10.11 cm2 V−1 s−1, and 1.38 × 1020 cm−3 on SmScO3 and 7.8 mΩ cm, 5.8 cm2 V−1 s−1, and 1.36 × 1020 cm−3 on SrTiO3 ruling out any extrinsic contribution from the substrate. The superior electrical properties observed on the SmScO3 substrate are attributed to reduction in dislocation density from the lower lattice mismatch.

Interfaces between different materials underpin both new scientific phenomena, such as the emergent behaviour at oxide interfaces, and key technologies, such as that of the transistor. Control of the interfaces between materials with the same crystal structures but different chemical compositions is possible in many materials classes, but less progress has been made for oxide materials with different crystal structures. We show that dynamical self-organization during growth can create a coherent interface between the perovskite and fluorite oxide structures, which are based on different structural motifs, if an appropriate choice of cations is made to enable this restructuring. The integration of calculation with experimental observation reveals that the interface differs from both the bulk components and identifies the chemical bonding requirements to connect distinct oxide structures.

Correlated metallic transition metal oxides offer a route to thin film transparent conductors that is distinct from the degenerate doping of broadband wide gap semiconductors. In a correlated metal transparent conductor, interelectron repulsion shifts the plasma frequency out of the visible region to enhance optical transmission, while the high carrier density of a metal retains sufficient conductivity. By exploiting control of the filling, position, and width of the bands derived from the B site transition metal in ABO 3 perovskite oxide films, it is shown that pulsed laser deposition-grown films of cubic SrMoO 3 and orthorhombic CaMoO 3 based on the second transition series cation 4d 2 Mo 4+ have superior transparent conductor properties to those of the first transition series 3d 1 V 4+ -based SrVO 3 . The increased carrier concentration offered by the greater bandfilling in the molybdates gives higher conductivity while retaining sufficient correlation to keep the plasma edge below the visible region. The reduced binding energy of the n=4 frontier orbitals in the second transition series materials shifts the energies of oxide 2p to metal nd transitions into the near-ultraviolet to enhance visible transparency. The A site sizedriven rotation of MoO 6 octahedra in CaMoO 3 optimizes the balance between plasma frequency and conductivity for transparent conductor performance.

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Multiferroics intertwine ferroelectric and ferromagnetic properties, allowing for novel ways of manipulating data and storing information. To optimize the unique Bi 6 Ti x Fe y Mn z O 18 (B6TFMO), multiferroic, ultrathin (<7 nm) epitaxial films were synthesized by direct liquid injection chemical vapor deposition (DLI-CVD). Epitaxial growth is, however, confounded by the volatility of bismuth, particularly when utilizing a postgrowth anneal at 850 °C. This results in microstructural defects, intergrowths of differing Aurivillius phases, and formation of impurities. Improved single-step DLI-CVD processes were subsequently developed at 710 and 700 °C, enabling lowering of crystallization temperature by 150 °C and significantly enhancing film quality and sample purity. Ferroelectricity is confirmed in 5 nm (1 unit-cell thick) B6TFMO films, with tensile epitaxial strain enhancing the piezoresponse. In-plane ferroelectric switching is demonstrated at 1.5 unitcell thickness. The persistence of stable ferroelectricity near unit-cell thickness in B6TFMO, both in-plane and out-of-plane, is significant and initiates possibilities for miniaturizing novel multiferroic-based devices.