Structure and Electronic Transport in BaSnO$_{3}$ Deposited \textit{via} High Pressure Oxygen Sputtering

We present structural and electronic transport properties of oxygen vacancy-doped BaSnO$_{3}$ films grown on SrTiO$_{3}$(001) and MgO(001) using the high pressure oxygen sputtering technique. High-resolution x-ray diffraction (HRXRD), combined with scanning transmission electron microscopy (STEM), confirms phase-pure epitaxial BaSnO$_{3}$(001) films on both substrates. The out-of-plane lattice parameter obtained from wide-angle x-ray diffraction is used as a sensitive probe for cation stoichiometry and strain relaxation. Irrespective of growth parameters, the out of plane lattice parameter remains unchanged, close to that of bulk (4.116 {\AA}). A detailed thickness-dependent structural study using HRXRD and STEM suggests the formation of misfit dislocations as the primary mechanism for strain relaxation. We further show that as-grown, insulating BaSnO$_{3}$ films can be made conductive with n-type carriers (with typical room temperature concentrations and Hall mobilities being 10$^{19}$ cm$^{-3}$ and 12 cm$^{2}$V$^{-1}$s$^{-1})$ via high temperature (900 $^{\circ}$C) vacuum annealing. Analysis of transport data from films with fixed density indicates a significant influence of film thickness, and thus strain relaxation, on the electron mobility. Temperature-dependent transport and magnetotransport studies will be described in detail as a function of annealing conditions, and will be correlated to strain relaxation. This work is supported by NSF through the UMN MRSEC.