A Scanning Tunneling Microscopy Study of the Reduced Tio2(110)Surface

Abstract

ABSTRACTThe scanning tunneling microscope has been used to image a reduced TiO2(110) surface in ultrahigh vacuum. Structural units with periodicities ranging from 21Å to 3.4Å have been clearly imaged and the observed surface structures can be explained by a model involving ordered arrangements of two dimensional defects known as crystallographic shear planes. An electronic state 0.5 eV below the conduction band edge, detected in tunneling spectra, has been assigned to reduced Ti cations which reside along the crystallographic shear planes. This state appears to be empty at the surface, possibly due to asmall amount of band bending. The results indicate that the topography of nonstoichiometric oxide surfaces can be rather complex and that the tunneling microscope provides an effective tool for studying the tomic scale surface features of wide band gap semiconductors.