Atomic control of SrTiO3 surface for perfect epitaxy of perovskite oxides

Atomically smooth SrTiO3(100) surface having one unit cell high steps and atomically flat terraces was obtained by selective etching of SrO atomic layer in a NH4FHF solution. Carbon contamination on the as-etched surface could be removed by annealing above 600°C in UHV, as verified by Auger electron spectroscopy and low energy electron diffraction. Atomically flat terraces corrugated with a spacing of 0.4 nm was observed by scanning tunneling microscopy. The intensity oscillation of reflection high energy electron diffraction was continuously observed during the homoepitaxy on the surface by laser molecular beam epitaxy, proving the requisite of this wet-treated substrate for the perfect epitaxy of perovskite oxides.