Scanning Tunneling Microscopy and Spectroscopy Observation of Reduced BaTiO3(100) Surface

Abstract
Microscopic structure and electronic states on the BaTiO3(100) single-crystal surfaces annealed in ultrahigh vacuum were observed by scanning tunneling microscopy and spectroscopy (STM/S). The surface step edges aligned preferentially along the [001] family of axes as the annealing temperature was increased. After annealing at temperatures above 800° C, spatial ordering of Ti 3d-oxygen vacancy complexes appeared on the surface. The STS spectra showed in-gap electronic states at about 1.0 eV below Fermi energy, which agreed well with the results of ultraviolet photoelectron spectroscopy previously reported.