High-temperature-grown buffer layer boosts electron mobility in epitaxial La-doped BaSnO${}_3$/SrZrO${}_3$ heterostructures

By inserting a SrZrO${}_3$ buffer layer between the film and the substrate, we demonstrate a significant reduction of the threading dislocation density with an associated improvement of the electron mobility in La:BaSnO${}_3$ films. A room temperature mobility of 140 cm${}^2$ V${}^{-1}{\text{s}}^{-1}$ is achieved for 25-nm-thick films without any post-growth treatment. The density of threading dislocations is only $4.9\times {10}^9$ cm${}^{-2}$ for buffered films prepared on (110) TbScO${}_3$ substrates by pulsed laser deposition.