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Surface states, surface potentials, and segregation at surfaces of tin-doped In2O3

Gassenbauer, Y. and Schafranek, R. and Klein, Andreas and Zafeiratos, S. and Hävecker, M. and Knop-Gericke, A. and Schlögl, R. (2006):
Surface states, surface potentials, and segregation at surfaces of tin-doped In2O3.
In: Physical Review B, pp. 245312-1, 73, (24), ISSN 1098-0121,
[Online-Edition: http://dx.doi.org/10.1103/PhysRevB.73.245312],
[Article]

Abstract

Surfaces of In2O3 and tin-doped In2O3 (ITO) were investigated using photoelectron spectroscopy. Parts of the measurements were carried out directly after thin film preparation by magnetron sputtering without breaking vacuum. In addition samples were measured during exposure to oxidizing and reducing gases at pressures of up to 100 Pa using synchrotron radiation from the BESSY II storage ring. Reproducible changes of binding energies with temperature and atmosphere are observed, which are attributed to changes of the surface Fermi level position. We present evidence that the Fermi edge emission observed at ITO surfaces is due to metallic surface states rather than to filled conduction band states. The observed variation of the Fermi level position at the ITO surface with experimental conditions is accompanied by a large apparent variation of the core level to valence band maximum binding energy difference as a result of core-hole screening by the free carriers in the surface states. In addition segregation of Sn to the surface is driven by the surface potential gradient. At elevated temperatures the surface Sn concentration reproducibly changes with exposure to different environments and shows a correlation with the Fermi level position.

Item Type: Article
Erschienen: 2006
Creators: Gassenbauer, Y. and Schafranek, R. and Klein, Andreas and Zafeiratos, S. and Hävecker, M. and Knop-Gericke, A. and Schlögl, R.
Title: Surface states, surface potentials, and segregation at surfaces of tin-doped In2O3
Language: English
Abstract:

Surfaces of In2O3 and tin-doped In2O3 (ITO) were investigated using photoelectron spectroscopy. Parts of the measurements were carried out directly after thin film preparation by magnetron sputtering without breaking vacuum. In addition samples were measured during exposure to oxidizing and reducing gases at pressures of up to 100 Pa using synchrotron radiation from the BESSY II storage ring. Reproducible changes of binding energies with temperature and atmosphere are observed, which are attributed to changes of the surface Fermi level position. We present evidence that the Fermi edge emission observed at ITO surfaces is due to metallic surface states rather than to filled conduction band states. The observed variation of the Fermi level position at the ITO surface with experimental conditions is accompanied by a large apparent variation of the core level to valence band maximum binding energy difference as a result of core-hole screening by the free carriers in the surface states. In addition segregation of Sn to the surface is driven by the surface potential gradient. At elevated temperatures the surface Sn concentration reproducibly changes with exposure to different environments and shows a correlation with the Fermi level position.

Journal or Publication Title: Physical Review B
Volume: 73
Number: 24
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Surface Science
Zentrale Einrichtungen
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > D - Component properties
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > D - Component properties > Subproject D3: Function and fatigue of oxide electrodes in organic light emitting diodes
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres
DFG-Collaborative Research Centres (incl. Transregio)
Date Deposited: 16 Sep 2011 13:09
Official URL: http://dx.doi.org/10.1103/PhysRevB.73.245312
Additional Information:

SFB 595 D3

Identification Number: doi:10.1103/PhysRevB.73.245312
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