Atomically flat single-terminated SrTiO3 (111) surface

The authors have reproducibly obtained an atomically well-defined SrTiO3 (111) surface by a combined chemical etching and thermal annealing process. Although thermodynamic mixed termination is preferred as a means of suppressing the surface dipole, the kinetics-driven etching process, via selective etching of SrO34−, enables a single-terminated surface to be obtained. Subsequent O2 annealing of the etched surface produces a clear step-and-terrace structure. Atomically flat terraces and only one-unit-cell-high step edges are observed, signifying a single-terminated surface. This study might pave the way for constructing (111)-oriented perovskite oxide superlattices, which would be expected to demonstrate new and better physical phenomena and functionalities.