Ultraviolet-visible absorption spectra of N-doped TiO2 film deposited on sapphire
2006; American Institute of Physics; Volume: 100; Issue: 11 Linguagem: Inglês
10.1063/1.2400099
ISSN1520-8850
AutoresJaewon Park, Jung Yeop Lee, Jun‐Hyung Cho,
Tópico(s)Gas Sensing Nanomaterials and Sensors
ResumoThe optical-response properties of nitrogen(N)-doped titanium dioxide (TiO2) films are investigated by means of a combination of ultraviolet-visible absorption spectroscopy and first-principles density-functional calculations. The TiO2 films were epitaxially grown on the sapphire substrate by the pulsed laser deposition method. The doping of N atoms was achieved by 70keV of N+ ion implantation, followed by postirradiation heat treatment at 550°C for 2h in air. We find that when 5×1016 (1×1017)Nions∕cm2 were implanted into the epitaxially grown TiO2 film, the absorption edge is reproducibly shifted to lower energy by about 0.06 (0.12)eV together with a significant optical absorption extending into the visible-light region. These experimental data can be explained by our calculated band structure of N-doped TiO2, where the bands originating from N 2p states locate above the valence band edge, while the band gap narrowing due to the mixing of N with O 2p states is 0.04eV.
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