THE TEMPERATURE-DEPENDENT SURFACE STRUCTURE, COMPOSITION AND ELECTRONIC PROPERTIES OF THE CLEAN SrTiO3(111) CRYSTAL FACE: LEED, AES, ELS AND UPS STUDIES

Low-energy-electron diffraction, Auger-electron spectroscopy, electron-energy-loss, and ultraviolet-photoelectron spectroscopies were used to study the structure, composition, and electron energy distribution of a clean single-crystal (111) face of strontium titanate (perovskite). The dependence of the surface chemical composition on the temperature has been observed along with corresponding changes in the surface electronic properties. High-temperature Ar-ion bombardment causes an irreversible change in the surface structure, stoichiometry, and electron energy distribution. In contrast to the TiO{sub 2} surface, there are always significant concentrations of Ti{sup 3+} in an annealed ordered SrTiO{sub 3} (111) surface. This stable active Ti{sup 3+} monolayer on top of a substrate with large surface dipole potential makes SrTiO{sub 3} superior to TiO{sub 2} when used as a photoanode in the photoelectrochemical cell.