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

La-doped BaSnO3 (LBSO) epitaxial thin films were grown on (001) MgO substrates by pulsed laser deposition using a La0.04Ba0.96SnO3 target. The structural, electrical, and optical properties of the LBSO films were inves-tigated as a function of oxygen pressure during deposition. The carrier mobility can be tuned from 13 cm2V- 1s- 1 to 44 cm2V- 1s- 1 by varying oxygen partial pressure from 2 Pa to 12 Pa, respectively. This improved mobility is attributed to the reduced film strain via reducing oxygen defect concentration or reducing off-stoichiometry in the film. The optical permittivity of LBSO films can also be modified as a function of the oxygen pressure during deposition, allowing tuning of their epsilon-near-zero wavelength from 1.9 mu m to 5.6 mu m. These results demonstrate that LBSO thin films grown on MgO can be used for plasmonic devices at mid-wave infrared wavelengths.