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

Diana E. Proffit*, Steven P. Harvey, Andreas Klein, Robert Schafranek, Jonathan Daniel Emery, D. Bruce Buchholz, R P H Chang, Michael J Bedzyk, Thomas O Mason

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Scopus citations

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 In 2O 3 (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 In 2O 3. 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 SnO 2, Al-doped ZnO, Sn-doped In 2O 3), making ZITO more versatile for applications.

Original languageEnglish (US)
Pages (from-to)5633-5639
Number of pages7
JournalThin Solid Films
Volume520
Issue number17
DOIs
StatePublished - Jun 30 2012

Keywords

  • Indium tin oxide
  • Thin film
  • Transparent conducting oxide
  • Ultraviolet photoelectron spectroscopy
  • Work function
  • X-ray photoelectron spectroscopy
  • Zinc indium tin oxide

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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