Low Optical Loss in Plasmonic Transparent Conducting La:BaSnO3 Films with High Thermal Stability

Low optical loss and refractory plasmonic materials are essential for developing high-performance nanophotonic and plasmonic devices with long-term reliability. However, the search for low-loss and refractory plasmonic materials is challenging due to the scarcity of these materials. In this work, perovskite La-doped BaSnO3 (LBSO) epitaxial films, as a promising candidate for low-loss and refractory plasmonic materials, have been successfully grown by high argon pressure magnetron sputtering. These LBSO films show excellent crystalline quality, high electron mobility (e.g., 120 cm2 V–1 s–1 at 4.0 × 1020 cm–3), low dielectric loss (e.g., dielectric loss ε2 of 0.31 measured at the zero-crossing wavelength of 1825 nm), high figures of merit for surface plasmon polariton and nonlinear performance, and superior thermal stability (800 °C), which outperform those of conventional transparent conducting oxide (TCO) films, e.g., indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO) films. The low loss in LBSO films mainly arises from their larger electron scattering time. This work demonstrates that high-quality LBSO epitaxial films can serve as low-loss and refractory plasmonic materials applied in robust and high-performance plasmonic and nanophotonic devices.