Prediction of a Mobile Two-Dimensional Electron Gas at the LaScO₃/BaSnO₃ (001) Interface

Two-dimensional electron gases (2DEG) at oxide interfaces, such as LaAlO₃/SrTiO₃ (001), have aroused significant interest due to their high carrier density (~10¹⁴ cm^-2) and strong lateral confinement (~1 nm). However, these 2DEGs are normally hosted by the weakly dispersive d-bands (e. g., Ti-3d bands), which are strongly coupled to the lattice, causing mobility of such 2DEGs to be relatively low at room temperature (~1 cm²/Vs). Here, we propose using oxide host with the conduction bands formed from s-obitals to increase carrier mobility and soften its temperature dependence. Using the density functional theory calculations, we investigate LaScO₃/BaSnO₃ (001) heterostructure and as a model system, where the conduction band hosts the s-like carriers. We find that the polar discontinuity at this interface leads to electronic reconstruction resulting in the formation of the 2DEG. The conduction electrons reside in the highly dispersive Sn-5s bands, which have a large band width and a low effective mass. We expect the predicted 2DEG to be highly mobile, even at room temperature and bring about more pronounced quantum phenomena. A qualitatively similar behavior is predicted for a doped BaSnO₃, where a monolayer of BaO is replaced with LaO.