Employing high-temperature-grown SrZrO₃ buffer to enhance the electron mobility in La:BaSnO₃-based heterostructures

We report a synthetic route to achieve high electron mobility at room temperature in epitaxial La:BaSnO₃/SrZrO₃ heterostructures prepared on several oxide substrates. Room-temperature mobilities of 157, 145, and 143 cm²V⁻¹s⁻¹ are achieved for heterostructures grown on DyScO₃ (110), MgO (001), and TbScO₃ (110) crystalline substrates, respectively. This is realized by first employing pulsed laser deposition to grow at very high temperature the SrZrO₃ buffer layer to reduce dislocation density in the active layer, then followed by the epitaxial growth of an overlaying La:BaSnO₃ active layer by molecular-beam epitaxy. Structural properties of these heterostructures are investigated, and the extracted upper limit of threading dislocations is well below $1.0 × 10 10$ cm⁻² for buffered films on DyScO₃, MgO, and TbScO₃ substrates. The present results provide a promising route toward achieving high mobility in buffered La:BaSnO₃ films prepared on most, if not all, oxide substrates with large compressive or tensile lattice mismatches to the film.