Surface Structure of Srtio₃(001) with Various Surface Treatments

Three kinds of SrTiO₃(001) surfaces, Ti0₂terminated, SrO terminated, and a mixture of these surfaces, are selectively formed and their surface structures are examined by means of reflection high energy electron diffraction, x-ray photoelectron spectroscopy, and x-ray photoelectron diffraction. The Ti0₂terminated surface is obtained under a moderate temperature (<700 K) cleaning by the Bi deposition/desorption method and subsequent oxidation, where the distance between the first Ti0₂plane and the SrO plane underneath is 1.95+0.07 A and the oxygen of the first Ti0₂plane is pulled out 0.10 A. The SrO terminated surface is obtained by growing one monolayer of SrO on the Ti0₂terminated surface, where the distance between the first SrO plane and Ti0₂plane underneath is 1.95+0.10 A and the oxygen of the first SrO plane is pulled out 0.16 A. These two surfaces are different from the surface obtained by Ar⁺sputtering and annealing, which is found to be the mixture of Ti0₂and SrO terminated surfaces.