Atomically Defined Rare‐Earth Scandate Crystal Surfaces

Abstract The fabrication of well‐defined, atomically sharp substrate surfaces over a wide range of lattice parameters is reported, which is crucial for atomically regulated epitaxial growth of complex oxide heterostructures. By applying a framework for controlled selective wet etching of complex oxides on the stable rare‐earth scandates (REScO₃), a_pseudocubic = 0.394 – 0.404 nm, the large chemical sensitivity of REScO₃ to basic solutions is exploited, which results in reproducible, single‐terminated surfaces. Time‐of‐flight mass‐spectroscopy measurements show that after wet etching the surfaces are predominantly ScO₂ ‐terminated. Moreover, the morphology study of SrRuO₃ thin‐film growth gives no evidence for mixed termination. Therefore, it is concluded that the REScO₃ surfaces are completely ScO₂ ‐terminated.