Employing High-temperature-grown SrZrO${}_3$ Buffer to Enhance the Electron Mobility in La:BaSnO${}_3$-based Heterostructures

We report a synthetic route to achieve high electron mobility at room temperature in epitaxial La:BaSnO${}_3$/SrZrO${}_3$ heterostructures prepared on several oxide substrates. Room-temperature mobilities of 157, 145, and 143 cm${}^2$V${}^{-1}$s${}^{-1}$ are achieved for heterostructures grown on DyScO${}_3$ (110), MgO (001), and TbScO${}_3$ (110) crystalline substrates, respectively. This is realized by first employing pulsed laser deposition to grow at very high temperature the SrZrO${}_3$ buffer layer to reduce dislocation density in the active layer, then followed by the epitaxial growth of an overlaying La:BaSnO${}_3$ active layer by molecular-beam epitaxy. Structural properties of these heterostructures are investigated, and the extracted upper limit of threading dislocations is well below $1.0\times {10}^{10}$cm${}^{-2}$ for buffered films on DyScO${}_3$, MgO, and TbScO${}_3$ substrates. The present results provide a promising route towards achieving high mobility in buffered La:BaSnO${}_3$ films prepared on most, if not all, oxide substrates with large compressive or tensile lattice mismatches to the film.