Surface structure of SrTiO3(001) with various surface treatments

Three kinds of SrTiO3(001) surfaces, TiO2 terminated, 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 TiO2 terminated 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 TiO2 plane and the SrO plane underneath is 1.95+0.07 Å and the oxygen of the first TiO2 plane is pulled out 0.10 Å. The SrO terminated surface is obtained by growing one monolayer of SrO on the TiO2 terminated surface, where the distance between the first SrO plane and TiO2 plane underneath is 1.95+0.10 Å and the oxygen of the first SrO plane is pulled out 0.16 Å. These two surfaces are different from the surface obtained by Ar+ sputtering and annealing, which is found to be the mixture of TiO2 and SrO terminated surfaces.