Effects of UV-ozone treatment on radio-frequency magnetron sputtered ZnO thin films

Wing Man Tang, M. T. Greiner, Z. H. Lu, W. T. Ng, H. G. Nam

Research output: Journal article publicationJournal articleAcademic researchpeer-review

18 Citations (Scopus)

Abstract

The effects of UV-ozone treatment on ZnO thin films prepared by using radio-frequency magnetron sputtering are investigated. Decrease in the density of oxygen vacancy as well as increase in the density of oxygen interstitial were inferred from the UV-ozone treated samples. It was also found that a considerable difference in the work function (0.25 eV) is induced by UV-ozone treatment implying a shift in Fermi level. This shift was confirmed by capacitance-voltage measurements, which demonstrated that the boundary between the inversion region and the depletion region of a ZnO-based metal-oxide-semiconductor (MOS) capacitor positively shifts when UV ozone treated. Our results clearly indicate that the threshold voltage of a thin film transistor can be adjusted by modifying the ZnO surface via UV ozone treatment. MOS capacitors fabricated with UV-ozone treated HfO2and/or ZnO also yielded a smaller leakage current (~ 73%-90% smaller) and a larger breakdown voltage (~ 8%-11% larger). The physical mechanism behind the effect of the UV ozone treatment is addressed in this study with the help of X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy.
Original languageEnglish
Pages (from-to)569-573
Number of pages5
JournalThin Solid Films
Volume520
Issue number1
DOIs
Publication statusPublished - 31 Oct 2011
Externally publishedYes

Keywords

  • Metal-oxide-semiconductor capacitor
  • Thin films
  • Threshold voltage
  • UV-ozone treatment
  • X-ray photoelectron spectroscopy
  • Zinc 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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