High-Mobility Field-Effect Transistor Using 2-Dimensional Electron Gas at the LaScO₃/BaSnO₃ Interface

A 2-dimensional electron gas (2DEG) system with high mobility was discovered at the interface of two perovskite oxides: a polar orthorhombic perovskite LaScO3 and a nonpolar cubic perovskite BaSnO3. Upon depositing the LaScO3 film on the BaSnO3 film, we measured the conductance enhancement and the resulting 2DEG density (n2D). Comparing the results with the previously reported LaInO3/BaSnO3 polar interface, we applied the "interface polarization" model to the LaScO3/BaSnO3 system, in which the polarization exists only over four pseudocubic unit cells in LaScO3 from the interface and vanishes afterward like the LaInO3/BaSnO3 interface. Based on the calculations of the self-consistent Poisson–Schrödinger equations, the LaScO3 thickness dependence of n2D of the LaScO3/BaSnO3 heterointerface is consistent with this model. Furthermore, a single subband in the quantum well is predicted. By use of the conductive interface and the LaScO3 as a gate dielectric, a 2DEG transistor composed of only perovskite oxides with high field-effect mobility (μFE) close to 100 cm2 V–1 s–1 is demonstrated.