Enhanced electron mobility at the two-dimensional metallic surface of BaSnO₃ electric-double-layer transistor at low temperatures

Wide-bandgap oxides exhibiting high electron mobility hold promise for the development of useful electronic and optoelectronic devices as well as for basic research on two-dimensional electron transport phenomena. A perovskite-type tin oxide, BaSnO₃, is currently one of such targets owing to distinctly high mobility at room temperature. The challenge to overcome towards the use of BaSnO₃ thin films in applications is suppression of dislocation scattering, which is one of the dominant scattering origins for electron transport. Here, we show that the mobility of the BaSnO₃ electric-double-layer transistor reaches 300 cm² V⁻¹ s⁻¹ at 50 K. The improved mobility indicates that charged dislocation scattering is effectively screened by electrostatically doped high-density charge carriers. We also observed metallic conduction persisting down to 2 K, which is attributed to the transition to the degenerate semiconductor. The experimental verification of bulk-level mobility at the densely accumulated surface sheds more light on the importance of suppression of dislocation scattering by interface engineering in doped BaSnO₃ thin films for transparent electrode applications.