N Doping of TiO2(110): Photoemission and Density-Functional Studies
The electronic properties of N-doped rutile TiO{sub 2}(110) have been investigated using synchrotron-based photoemission and density-functional calculations. The doping via N{sub 2}{sup +} ion bombardment leads to the implantation of N atoms ({approx}5% saturation concentration) that coexist with O vacancies. Ti 2p core level spectra show the formation of Ti{sup 3+} and a second partially reduced Ti species with oxidation states between +4 and +3. The valence region of the TiO{sub 2-x}N{sub y}(110) systems exhibits a broad peak for Ti{sup 3+} near the Fermi level and N-induced features above the O 2p valence band that shift the edge up by {approx}0.5 eV. The magnitude of this shift is consistent with the 'redshift' observed in the ultraviolet spectrum of N-doped TiO{sub 2}. The experimental and theoretical results show the existence of attractive interactions between the dopant and O vacancies. First, the presence of N embedded in the surface layer reduces the formation energy of O vacancies. Second, the existence of O vacancies stabilizes the N impurities with respect to N{sub 2}(g) formation. When oxygen vacancies and N impurities are together there is an electron transfer from the higher energy 3d band of Ti{sup 3+} to the lower energy 2p band of the N{sup 2-} impurities.
- Research Organization:
- Brookhaven National Laboratory (BNL) National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 913965
- Report Number(s):
- BNL--78533-2007-JA
- Journal Information:
- J. Chem. Phys., Journal Name: J. Chem. Phys. Vol. 125; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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