Probing surface band bending of surface-engineered metal oxide nanowires

Cheng Ying Chen, Jose Ramon Duran Retamal, I. Wen Wu, Der Hsien Lien, Ming Wei Chen, Yong Ding, Yu Lun Chueh, Chih I. Wu, Jr-Hau He*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

143 Scopus citations


We in situ probed the surface band bending (SBB) by ultraviolet photoelectron spectroscopy (UPS) in conjunction with field-effect transistor measurements on the incompletely depleted ZnO nanowires (NWs). The diameter range of the NWs is ca. 150-350 nm. Several surface treatments (i.e., heat treatments and Au nanoparticle (NP) decoration) were conducted to assess the impact of the oxygen adsorbates on the SBB. A 100 °C heat treatment leads to the decrease of the SBB to 0.74 ± 0.15 eV with 29.9 ± 3.0 nm width, which is attributed to the removal of most adsorbed oxygen molecules from the ZnO NW surfaces. The SBB of the oxygen-adsorbed ZnO NWs is measured to be 1.53 ± 0.15 eV with 43.2 ± 2.0 nm width. The attachment of Au NPs to the NW surface causes unusually high SBB (2.34 ± 0.15 eV with the wide width of 53.3 ± 1.6 nm) by creating open-circuit nano-Schottky junctions and catalytically enhancing the formation of the charge O2 adsorbates. These surface-related phenomena should be generic to all metal oxide nanostructures. Our study is greatly beneficial for the NW-based device design of sensor and optoelectronic applications via surface engineering.

Original languageEnglish (US)
Pages (from-to)9366-9372
Number of pages7
JournalACS Nano
Issue number11
StatePublished - Nov 27 2012


  • Schottky junction
  • ZnO
  • metal oxide
  • nanowire
  • oxygen vacancy
  • surface band bending

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)


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