Formation of 2D Electron Gas at a Non‐Polar Perovskite Oxide Interface: SrHfO ₃ /BaSnO ₃

Abstract A consistent increase in conductance in La‐doped BaSnO ₃ (BLSO) is observed after forming an interface with the non‐polar perovskite SrHfO ₃ (SHO). The conductance enhancement at the SHO/BLSO interface is measured as a function of the thickness of the SHO layer and the La doping rate in the BLSO layer. A monotonic increase of conductance as a function of the SHO thickness is observed, unlike the case of polar interfaces of LaInO ₃ /BaSnO ₃ and LaScO ₃ /BaSnO ₃ . The first several unit cells of SHO have the most significant impact on conductance. It is also found that the SHO/BLSO interface requires little doping (≈0.2%) to compensate for the deep acceptors in BaSnO ₃ . To determine the charge carrier distribution, capacitance–voltage profiling is employed, which indicates that the charge carriers are confined within 1–2 nm of the interface. The observed 2D electron gas behavior at the interface is analyzed using a self‐consistent Poisson‐Schrödinger equation solver. This analysis provides a consistent picture of the SHO thickness and the La‐doping dependence of conductance enhancement at the SHO/BLSO interface, suggesting that the large conduction band offset at the SHO/BLSO interface and the intrinsic deep donor states in SHO are responsible for formation of a potential well in the BLSO side.