La-doped BaSnO3 films for near- and mid-infrared plasmonic applications

Recently, ternary perovskite oxides have attracted great attention as alternative transparent conducting oxides (TCOs) because their structures are compatible with many other perovskite oxides that allow devices to be fabricated comprised entirely of perovskite oxides. Among these perovskite oxides, BaSnO3 has attracted considerable attention as a promising TCO because of its high mobility at room temperature (~320 cm2V-1s-1 in bulk single crystals and ~100 cm2V-1s-1 in epitaxial thin films) and high temperature stability in oxygen atmospheres compared to other TCOs, such as In2O3, ZnO, and SnO2. The electrical and optical properties of the BaSnO3 can be improved by either inducing oxygen vacancies or cationic doping. We have grown epitaxial La-doped BaSnO3 (LBSO) thin films on MgO (001) substrates by pulsed laser deposition using a La0.04Ba0.96SnO3 target, and investigated their structural, electrical, and optical properties as a function of the oxygen pressure during deposition. The permittivity of the LBSO films can be modified as a function of the oxygen pressure during deposition allowing tuning of their epsilon-near-zero (ENZ) wavelength from 2.2 μm to 7 μm. We will present details of the deposition conditions on the properties of LBSO films and the ability to tune the permittivity in this infrared range.