AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS1+MC-WeA

Paper SS1+MC-WeA7
Metallic Electronic States on SrTiO@sub 3@ (110) Surface -- An In Situ Conduction Measurement

Wednesday, October 4, 2000, 4:00 pm, Room 208

Session: Oxide Surfaces, Interfaces and Defects
Presenter: H. Bando, Electrotechnical Laboratory, Japan
Authors: H. Bando, Electrotechnical Laboratory, Japan
Y. Ochiai, Ibaraki University, Japan
Y. Aiura, Electrotechnical Laboratory, Japan
Y. Haruyama, Himeji Institute of Technology, Japan
T. Yasue, University of Tsukuba, Japan
Y. Nishihara, Ibaraki University, Japan
Correspondent: Click to Email
In our previous works we detected metallic electronic states on the SrTiO@sub 3@ (110) surface after annealing in ultra high vacuum (UHV) at relatively low temperature, @<=@ 800 °C, based on a sharp Fermi edge detected by ultraviolet photoemission spectroscopy and finite zero-bias differential conductance by scanning tunneling spectroscopy. In order to verify the metallic feature of the surface as a macroscopic property, electric conductance is measured in situ. For the measurement, a sample holder is designed which enables both annealing in UHV by electron beam and 4-probe electric conduction measurement with uniform electric field. Conductance contributed by bulk is separated by measuring the decrease of total conductance by adsorption of oxygen at room temperature, which is supposed to modify only the surface electronic states. Surface conductance is deduced between 150 K to 300 K and showed a metallic feature. Comments will be presented on the effects of surface anisotropy and photo-induced carriers. Moreover, the surface conductance during exposure to oxygen is monitored in situ, and showed a reversible-like change depending on the oxygen pressure. This possibly evidences that the oxygen molecules which temporarily stay on the surface suppress the conduction by surface electrons.