Insulator–metal transition on heavily reduced TiO2(110) surface studied by high temperature-scanning tunnelling spectroscopy (HT-STS)

Abstract Scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS) were used to study the electronic structure of the reduced TiO 2 (1 1 0) surface. At the occupied part of the spectra some states at energies of about 1.1 and 0.6 eV below the Fermi level were found. At the unoccupied part of the spectra, the presence of a surface state at an energy of about 0.6 eV above the Fermi level was observed. Their presence has been ascribed to the appearance of Ti 2 O 3 regions on the TiO 2 (1 1 0) surface. High temperature spectroscopy measurements indicated smooth insulator–metal transition (I–M) caused by bands overlap in Ti 2 O 3 , which takes place at elevated temperatures.