Engineering two-dimensional electron gases at the (001) and (101) surfaces of TiO2 anatase using light

C. Roedel T. F. Fortuna 1 F. Bertran 2 M. Gabay J. Rozenberg M. F. Santander-Syro A. 3 P. Le Fevre 2
1 CSNSM PS2
CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière
2 CASSIOPEE
SSOLEIL - Synchrotron SOLEIL
3 CSNSM PS1
CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière
Abstract : We report the existence of metallic two-dimensional electron gases (2DEGs) at the (001) and (101) surfaces of bulk-insulating TiO2 anatase due to local chemical doping by oxygen vacancies in the near-surface region. Using angle-resolved photoemission spectroscopy, we find that the electronic structure at both surfaces is composed of two occupied subbands of d(xy) orbital character. While the Fermi surface observed at the (001) termination is isotropic, the 2DEG at the (101) termination is anisotropic and shows a charge carrier density three times larger than at the (001) surface. Moreover, we demonstrate that intense UV synchrotron radiation can alter the electronic structure and stoichiometry of the surface up to the complete disappearance of the 2DEG. These results open a route for the nanoengineering of confined electronic states, the control of their metallic or insulating nature, and the tailoring of their microscopic symmetry, using UV illumination at different surfaces of anatase.
Keywords : TITANIUM-DIOXIDE OXIDE INTERFACES ION DESORPTION SOLAR-CELLS SRTIO3 PHOTOCATALYSIS SEMICONDUCTORS FERROMAGNETISM CREATION SCIENCE
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Journal articles
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http://hal.in2p3.fr/in2p3-01186318
Contributor : Emilie Bonnardel <>
Submitted on : Monday, August 24, 2015 - 3:51:56 PM
Last modification on : Friday, March 15, 2019 - 2:28:06 PM

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C. Roedel T., F. Fortuna, F. Bertran, M. Gabay, J. Rozenberg M., et al.. Engineering two-dimensional electron gases at the (001) and (101) surfaces of TiO2 anatase using light. Physical Review B : Condensed matter and materials physics, American Physical Society, 2015, 92 (issue 4), pp.041106. ⟨10.1103/PhysRevB.92.041106⟩. ⟨in2p3-01186318⟩

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