Electronic structure of point defects in controlled self-doping of theTiO2(110) surface: Combined photoemission spectroscopy and density functional theory study

• DOI: 10.1103/physrevb.77.235424
• Publication Date: 2008-06-17T23:04:11Z
• Authors: Michael Nolan; Simon D. Elliott; James S. Mulley; Roger A. Bennett; Mark Basham; Paul Mulheran
• Keywords: Solid state physics. Nanoscience; 540; 530; 01 natural sciences; 0104 chemical sciences

Point defects in metal oxides such as ${\text{TiO}}_{2}$ are key to their applications numerous technologies. The investigation of thermally induced nonstoichiometry is complicated by the difficulties preparing and determining a desired degree nonstoichiometry. We study controlled self-doping adsorption 1/8 1/16 monolayer Ti at (110) surface using combination experimental computational approaches unravel details process oxidation state Ti. Upon Ti, x-ray ultraviolet photoemission spectroscopy (XPS UPS) show formation reduced Comparison pure density functional theory (DFT) with experiment shows that DFT provides an inconsistent description electronic structure. To surmount this difficulty, we apply corrected for on-site Coulomb interaction $(\text{DFT}+U)$ describe ions. optimal value $U$ 3 eV, determined from comparison computed $\text{Ti}\text{ }3d$ states UPS data. $\text{DFT}+U$ appearance adsorbate-induced 1.3 eV above valence band 1.0 below conduction band. computations adsorbed atom oxidized ${\text{Ti}}^{2+}$ fivefold coordinated ${\text{Ti}}^{3+}$, while remaining electron distributed among other atoms. data best fitted ${\text{Ti}}^{3+}$ These results demonstrate complexity doped understood appropriate computations.