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Surface studies of crystalline and amorphous Zn–In–Sn–O transparent conducting oxides

Proffit, Diana E. and Harvey, Steven P. and Klein, Andreas and Schafranek, Robert and Emery, Jonathan D. and Buchholz, D. Bruce and Chang, Robert P. H. and Bedzyk, Michael J. and Mason, Thomas O. (2012):
Surface studies of crystalline and amorphous Zn–In–Sn–O transparent conducting oxides.
In: Thin Solid Films, Elsevier Science Publishing, pp. 5633-5639, 520, (17), ISSN 00406090, [Online-Edition: http://dx.doi.org/10.1016/j.tsf.2012.04.075],
[Article]

Abstract

X-ray and ultraviolet photoelectron spectroscopy (UPS) studies were made of in situ RF magnetron-sputtered crystalline (c) and amorphous (a) Zn–In–Sn–O (ZITO) thin films, ex situ pulsed laser deposited c- and a-ZITO thin films, and bulk ZITO ceramics. Cosubstitution of Zn and Sn for In results in an increase of the In core level binding energy at a given Fermi level compared to that measured in undoped and Sn-doped In2O3 (ITO). In plots of work function vs. Fermi level, in situ c-ZITO and a-ZITO films have low ionization potentials (7.0–7.7 eV) that are similar to undoped In2O3. In contrast, dry-air-annealed in situ films, ex situ films, and bulk ceramics have higher ionization potentials (7.7–8.1 eV) that are more similar to ITO and match well with previous work on air-exposed surfaces. Kelvin Probe measurements were made of select a-ZITO films exposed to air and ultraviolet/ozone-treated so as to measure work functions under conditions commonly employed for device fabrication. Results (4.8–5.3 eV) were in good agreement with the UPS work functions of oxygen-exposed materials and with literature values. Lastly, a parallelogram plot of work function vs. Fermi level shows that a wider range of work functions is achievable in ZITO materials as compared to other transparent conducting oxides (Sb-doped SnO2, Al-doped ZnO, Sn-doped In2O3), making ZITO more versatile for applications.

Item Type: Article
Erschienen: 2012
Creators: Proffit, Diana E. and Harvey, Steven P. and Klein, Andreas and Schafranek, Robert and Emery, Jonathan D. and Buchholz, D. Bruce and Chang, Robert P. H. and Bedzyk, Michael J. and Mason, Thomas O.
Title: Surface studies of crystalline and amorphous Zn–In–Sn–O transparent conducting oxides
Language: English
Abstract:

X-ray and ultraviolet photoelectron spectroscopy (UPS) studies were made of in situ RF magnetron-sputtered crystalline (c) and amorphous (a) Zn–In–Sn–O (ZITO) thin films, ex situ pulsed laser deposited c- and a-ZITO thin films, and bulk ZITO ceramics. Cosubstitution of Zn and Sn for In results in an increase of the In core level binding energy at a given Fermi level compared to that measured in undoped and Sn-doped In2O3 (ITO). In plots of work function vs. Fermi level, in situ c-ZITO and a-ZITO films have low ionization potentials (7.0–7.7 eV) that are similar to undoped In2O3. In contrast, dry-air-annealed in situ films, ex situ films, and bulk ceramics have higher ionization potentials (7.7–8.1 eV) that are more similar to ITO and match well with previous work on air-exposed surfaces. Kelvin Probe measurements were made of select a-ZITO films exposed to air and ultraviolet/ozone-treated so as to measure work functions under conditions commonly employed for device fabrication. Results (4.8–5.3 eV) were in good agreement with the UPS work functions of oxygen-exposed materials and with literature values. Lastly, a parallelogram plot of work function vs. Fermi level shows that a wider range of work functions is achievable in ZITO materials as compared to other transparent conducting oxides (Sb-doped SnO2, Al-doped ZnO, Sn-doped In2O3), making ZITO more versatile for applications.

Journal or Publication Title: Thin Solid Films
Volume: 520
Number: 17
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: Work function, Indium tin oxide, Zinc indium tin oxide, Transparent conducting oxide, Ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, Thin film
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
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 > CRC 595: Electrical fatigue > D - Component properties
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue
Zentrale Einrichtungen
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres
DFG-Collaborative Research Centres (incl. Transregio)
Date Deposited: 28 Nov 2013 10:32
Official URL: http://dx.doi.org/10.1016/j.tsf.2012.04.075
Additional Information:

SFB 595 D3

Identification Number: doi:10.1016/j.tsf.2012.04.075
Funders: The Darmstadt efforts were supported by the German Science Foundation (DFG) in the framework of the Collaborative Research Center on Electrical Fatigue of Functional Materials (SFB 595, project D3), and by the DFG (grant no. KL1225/4)., The Northwestern synthetic and structural efforts were supported by the National Science Foundation (NSF, grant no. DMR-0602521, SPH, JDE, DBB, RPHC, MJB, TOM) and the surface studies were supported by the U.S. Department of Energy, , Office of Basic Energy Sciences as part of the ANSER Energy Frontier Research Center (DOE, grant no. DE-SC0001059, DEP, RPHC, TOM)., DEP also acknowledges support of an NSF Graduate Research Fellowship. Use of the Advanced Photon Source., An Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under contract no. DE-AC02-06CH11357.
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