High-resolution synchrotron-radiation photoemission characterization for atomically-controlled SrTiO3(001) substrate surfaces subjected to various surface treatments

The chemical properties and electronic structures of atomically flat ${\mathrm{SrTiO}}_3\left(001\right)$ substrates with various surface treatments have been investigated by high-resolution synchrotron-radiation photoemission spectroscopy. We have found that an annealing process causes the segregation of Sr oxides at the ${\mathrm{TiO}}_2$ -terminated surface and that the ${\mathrm{TiO}}_2$ -terminated surface is more stable than the SrO terminated one. We demonstrate that the use of chemical etching process is effective as a removal technique for Sr oxides accumulating on ${\mathrm{TiO}}_2$ -terminated surfaces and that the adding of a reetching process after annealing in an ${\mathrm{O}}_2$ environment is one of the best methods to obtain well defined and nearly perfect substrate surface.