Low-resistance nonalloyed ohmic contacts on undoped ZnO films grown by pulsed-laser deposition

Chia Lung Tsai, Yow Jon Lin, Yi Min Chin, W. R. Liu, W. F. Hsieh, C. H. Hsu, Jian An Chu

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14 Citations (Scopus)


We report on the formation of nonalloyed Ti and Ni ohmic contacts to ZnO films grown by pulsed-laser deposition. The experimental results show a lower barrier height of the Ti/ZnO samples than that of the Ni/ZnO samples (due to the lower work function of Ti than Ni), suggesting the Fermi-level unpinning at the interfaces. Based on the thermionic-emission or the thermionic-field-emission model, we found weak barrier-height dependence of the contact resistivity, implying that the presence of hydroxide in ZnO (i.e. the formation of the narrow depletion region at the metal/ZnO interface) resulted in the excess current component related to tunnelling, which led to the formation of the low-resistance nonalloyed metal/ZnO contact. The measurement temperature dependence of the contact resistivity revealed that the dominant current transport mechanism is field emission.

Original languageEnglish
Article number095108
JournalJournal of Physics D: Applied Physics
Issue number9
Publication statusPublished - 2009 May 7

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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