Surface Structure and Electronic Property of Reduced SrTiO₃(100) Surface Observed by Scanning Tunneling Microscopy/Spectroscopy

Abstract

We have obtained the scanning tunneling microscopy (STM) images and scanning tunneling spectroscopy (STS) data with atomic-scale resolution for a SrTiO 3 (100) surface annealed in ultrahigh vacuum (UHV) at 1200°C. A √5×√5- R 26.6° surface superstructure indicating oxygen vacancy ordering has been observed. The STS data provide evidence for a localized surface state arising from oxygen vacancies at 1.35 eV below the Fermi level. STM images of the √5×√5 structure correspond to the surface orbital of the ordered Ti-oxygen vacancy complex.