Atomic Control of the SrTiO 3 Crystal Surface

Abstract

The atomically smooth SrTiO₃ (100) with steps one unit cell in height was obtained by treating the crystal surface with a pH-controlled NH₄F-HF solution. The homoepitaxy of SrTiO₃ film on the crystal surface proceeds in a perfect layer-by-layer mode as verified by reflection high-energy electron diffraction and atomic force microscopy. Ion scattering spectroscopy revealed that the TiO₂ atomic plane terminated the as-treated clean surface and that the terminating atomic layer could be tuned to the SrO atomic plane by homooepitaxial growth. This technology provides a well-defined substrate surface for atomically regulated epitaxial growth of such perovskite oxide films as YBa₂Cu₃O_7-δ.