Structure and electronic states on reduced BaTiO3 (100) surface observed by scanning tunneling microscopy and spectroscopy

Structure and electronic states on the (100) surface of reduced BaTiO3 single crystals were observed by scanning tunneling microscopy and spectroscopy. after annealing at 1150 degrees C, the direction of the edges ordered to run along the equivalents of [011] and [001] directions. All the observed step edges were of unit-cell height. On each terrace atomlike corrugation with the periodicity multiples of the root 5 x root 5 R26.6 degrees superlattice was observed in the filled state images. A straightforward method to deduce the local density of states from the scanning tunneling spectroscopy data was introduced, based on multiplication of an inverted triangular transfer matrix, and was applied to the scanning tunneling spectroscopy data on the terraces. The amplitude of the local density of states at E(F) - 1 eV varied in phase with the atomlike corrugation on the terrace, which was consequently ascribed to electronic states at the spatially ordered Ti 3d-oxygen vacancy complexes on the surface. (C) 1996 American Vacuum Society.