One-step epitaxy of high-mobility La-doped BaSnO₃ films by high-pressure magnetron sputtering

As unique perovskite transparent oxide semiconductors, high-mobility La-doped BaSnO₃ films have been successfully synthesized by molecular beam epitaxy and pulsed laser deposition. However, it remains a big challenge for magnetron sputtering, a widely applied technique suitable for large-scale fabrication, to grow high-mobility La-doped BaSnO₃ films. In this work, we developed a method to synthesize high-mobility epitaxial La-doped BaSnO₃ films (with mobility up to 121 cm² V⁻¹ s⁻¹ at the carrier density of ∼4.0 × 10²⁰ cm⁻³ at room temperature) directly on SrTiO₃ single crystal substrates using high-pressure magnetron sputtering. The structural and electrical properties of La-doped BaSnO₃ films were characterized by combined high-resolution x-ray diffraction, x-ray photoemission spectroscopy, and temperature-dependent electrical transport measurements. The room-temperature electron mobility of La-doped BaSnO₃ films achieved in this work is two to four times higher than the reported values of the films grown by magnetron sputtering. Moreover, in the high carrier density range (n > 3 × 10²⁰ cm⁻³), the electron mobility value of 121 cm² V⁻¹ s⁻¹ achieved in our work is among the highest values for all reported doped BaSnO₃ films. It is revealed that high argon pressure during sputtering plays a vital role in stabilizing the fully relaxed films and inducing oxygen vacancies, which facilitates high mobility at room temperature. Our work provides an easy and economical way to massively synthesize high-mobility transparent conducting films for transparent electronics.