Unit-Cell by Unit-Cell Homoepitaxial Growth Using Atomically Flat SrTiO₃(001) Substrates and Pulsed Laser Deposition

Using a combination of chemical etching and thermal annealing methods, we have obtained atomically flat TiO₂-terminated SrTiO₃(001) with large terraces. The average width of the terrace is only determined by miscut angles. When we continuously grow tens of SrTiO₃ monolayers on such a surface under pulsed laser ablation deposition condition at 621°C, the growth proceeds in a layer-by-layer mode characterized by un-damped oscillations of the specular RHEED intensity. After the growth of 180 monolayers, the surface morphology is restored to the pre-growth condition with similarly large terraces after annealing in vacuum for only 30min, indicating efficient mass transfer on TiO₂-terminated terraces.