Engineering the LaScO₃/BaSnO₃ Interface for 2D Electron Gas Conductivity

Two-dimensional electron gases (2DEGs) at the interfaces of insulating oxide perovskites have attracted significant attention since the discovery of 2DEG behavior at the SrTiO₃/LaAlO₃ interface [1], underscoring the potential of these systems for advancing oxide electronics. The LaScO₃/BaSnO₃ system has been reported to exhibit 2DEG behavior with room-temperature carrier mobility as high as 60 cm²/Vs —an order of magnitude greater than that of SrTiO₃-based systems. However, achieving this required the fabrication of a BaSnO₃ pseudo-substrate, involving two deposition steps and high-temperature annealing to minimize threading dislocations [2], adding complexity to the process.

In this work, we systematically explore alternative fabrication conditions to engineer and optimize the interface of LaScO₃/BaSnO₃ heterostructures grown on single-terminated SrTiO₃ substrates using pulsed laser deposition in a single process. Through a combination of X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoemission spectroscopy, and transport measurements, we examine how fine-tuning the oxygen content in the BaSnO₃ layer influences the nanostructure, extended defect density, and electrical properties of the interface. Our work demonstrates that optimized heterostructures with low threading dislocation density and sheet resistance as low as 1 kΩ/sq can be achieved without the use of pseudo-substrates, opening new avenues for exploring novel physical effects in these intriguing systems.

[1] A. Ohtomo, H. Y. Hwang, Nature 427, 423 (2004)

[2] K. Eom et al., Adv. Science 9, 2105652 (2022)