Preparation of atomically-flat SrTiO3 surfaces using a deionized-water etching and thermal annealing procedure

We report that a deionized water etching and thermal annealing technique can be effective for preparing atomically-flat and singly-terminated surfaces of single crystalline SrTiO3 substrates. After a two-step thermal-annealing and deionized-water etching procedure, topography measured by atomic force microscopy shows the evolution of substrates from a rough to step-terraced surface structure. Lateral force microscopy confirms that the atomically-flat surfaces are singly-terminated. Moreover, this technique can be used to remove excessive strontium oxide or hydroxide composites segregated on the SrTiO3 surface. This acid-etchant-free technique facilitates the preparation of atomically-aligned SrTiO3 substrates, which promotes studies on two-dimensional physics of complex oxide interfaces.