Tunable permittivity of La-doped BaSnO3 thin films for near- and mid-infrared plasmonics

We report tunable permittivity of La-doped BaSnO3 (LBSO) epitaxial films in the near- and mid-infrared range. The structural, electrical transport, and optical properties of the LBSO thin films can be effectively modified by controlling oxygen concentration during film growth. The permittivity of the LBSO films can be modified as a function of the oxygen pressure and temperature during deposition, which allows the tuning of their epsilon-near-zero wavelength from 2 mu m to 5.6 mu m. The ability to tune the permittivity in this infrared range enables the use of LBSO films as active components in infrared plasmonic devices.