Analysis of Schottky contact formation in coplanar Au/ZnO/Al nanogap radio frequency diodes processed from solution at low temperature

James Semple, Stephan Rossbauer, Thomas D. Anthopoulos*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Much work has been carried out in recent years in fabricating and studying the Schottky contact formed between various metals and the n-type wide bandgap semiconductor zinc oxide (ZnO). In spite of significant progress, reliable formation of such technologically interesting contacts remains a challenge. Here, we report on solution-processed ZnO Schottky diodes based on a coplanar Al/ZnO/Au nanogap architecture and study the nature of the rectifying contact formed at the ZnO/Au interface. Resultant diodes exhibit excellent operating characteristics, including low-operating voltages (±2.5 V) and exceptionally high current rectification ratios of >106 that can be independently tuned via scaling of the nanogap's width. The barrier height for electron injection responsible for the rectifying behavior is studied using current-voltage-temperature and capacitance-voltage measurements (C-V) yielding values in the range of 0.54-0.89 eV. C-V measurements also show that electron traps present at the Au/ZnO interface appear to become less significant at higher frequencies, hence making the diodes particularly attractive for high-frequency applications. Finally, an alternative method for calculating the Richardson constant is presented yielding a value of 38.9 A cm-2 K-2, which is close to the theoretically predicted value of 32 A cm-2 K-2. The implications of the obtained results for the use of these coplanar Schottky diodes in radio frequency applications is discussed.

Original languageEnglish (US)
Pages (from-to)23167-23174
Number of pages8
JournalACS Applied Materials and Interfaces
Issue number35
StatePublished - Sep 7 2016

Bibliographical note

Funding Information:
We are grateful to the European Research Council (ERC) AMPRO grant number 280221 and the Engineering and Physical Sciences Research Council (EPSRC) grant number EP/P505550/1 and the EPSRC Centre for Innovative Manufacturing in Large Area Electronics (CIM-LAE) grant no. EP/K03099X/1 for financial support.

Publisher Copyright:
© 2016 American Chemical Society.


  • RFID
  • Richardson constant
  • ZnO
  • adhesion lithography
  • planar Schottky diode
  • radio frequency diode
  • solution processing

ASJC Scopus subject areas

  • Materials Science(all)


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