Effects of Hydrogen on the Electronic State and Electric Conductivity of the Rutile TiO₂(110) Surface

Abstract

The adsorption of atomic hydrogen on a rutile TiO2(110) surface was investigated by nuclear reaction analysis (NRA), ultraviolet photoelectron spectroscopy (UPS), and conductivity measurements. The TiO2(110) surface was annealed in O2 of 1 × 10−4 Pa, which is regarded as a quasi-stoichiometric surface. After exposure to atomic hydrogen, UPS showed a localized in-gap state (IGS) at about 0.8 eV below the Fermi level and downward band bending with a decrease in the work function. Along with these changes, the conductivity was increased by 2.9 µS/□. Our results indicate that hydrogen donates electrons to the substrate. The amount of charge transfer and electric conductivity are discussed on the basis of the experimental data.