Structures and chemistry of the annealed SrTiO3(001) surface

Surface structures and chemistry of the annealed SrTiO₃(001) have been studied by scanning tunneling microscopy and Auger electron spectroscopy. Our STM results show that islands arc formed on an originally smooth surface after annealing in ultra high vacuum at a temperature of 1300°C. Tunneling spectra show that the islands exhibit a different electronic structure than that of SrTiO₃, with an apparent bandgap of 6 eV rather than 3.2 eV. Auger electron spectroscopy indicates that annealing yields strontium enrichment at the surface. The nature of the islands and change of surface chemistry are discussed in terms of correlation of the STM and Auger results.