Ohmic-rectifying conversion of Ni contacts on ZnO and the possible determination of ZnO thin film surface polarity

PLoS One. 2014 Jan 23;9(1):e86544. doi: 10.1371/journal.pone.0086544. eCollection 2014.

Abstract

The current-voltage characteristics of Ni contacts with the surfaces of ZnO thin films as well as single crystal (0001) ZnO substrate are investigated. The ZnO thin film shows a conversion from Ohmic to rectifying behavior when annealed at 800°C. Similar findings are also found on the Zn-polar surface of (0001) ZnO. The O-polar surface, however, only shows Ohmic behavior before and after annealing. The rectifying behavior observed on the Zn-polar and ZnO thin film surfaces is associated with the formation of nickel zinc oxide (Ni1-xZnxO, where x = 0.1, 0.2). The current-voltage characteristics suggest that a p-n junction is formed by Ni1-xZnxO (which is believed to be p-type) and ZnO (which is intrinsically n-type). The rectifying behavior for the ZnO thin film as a result of annealing suggests that its surface is Zn-terminated. Current-voltage measurements could possibly be used to determine the surface polarity of ZnO thin films.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallization
  • Electric Conductivity*
  • Materials Testing
  • Nickel / chemistry*
  • Surface Properties
  • X-Ray Diffraction
  • Zinc Oxide / chemistry*

Substances

  • Nickel
  • Zinc Oxide

Grants and funding

Funding from Universiti Sains Malaysia (Grant no. 304/PJJAUH/6311098). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.