Influence of polarity and hydroxyl termination on the band bending at ZnO surfaces

R. Heinhold*, G. T. Williams, S. P. Cooil, D. A. Evans, M. W. Allen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

86 Citations (SciVal)
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Abstract

Surface sensitive synchrotron x-ray photoelectron spectroscopy (XPS) and real-time in situ XPS were used to study the thermal stability of the hydroxyl termination and downward band bending on the polar surfaces of ZnO single crystals. On the O-polar face, the position of the Fermi level could be reversibly cycled between the conduction band and the band gap over an energetic distance of approximately 0.8 eV (similar to 1/4 of the band gap) by controlling the surface H coverage using simple ultrahigh vacuum (UHV) heat treatments up to 750 degrees C, dosing with H2O/H-2 and atmospheric exposure. A metallic to semiconductorlike transition in the electronic nature of the O-polar face was observed at an H coverage of approximately 0.9 monolayers. For H coverage less than this, semiconducting (depleted) O-polar surfaces were created that were reasonably stable in UHV conditions. In contrast, the downward band bending on the Zn-polar face was significantly more resilient, and depleted surfaces could not be prepared by heat treatment alone.

Original languageEnglish
Article number235315
Number of pages9
JournalPhysical Review B
Volume88
Issue number23
DOIs
Publication statusPublished - 30 Dec 2013

Keywords

  • ZNO(0001) SURFACES
  • OXIDE SURFACES
  • N-TYPE
  • STABILIZATION
  • WATER
  • RECONSTRUCTION
  • ADSORPTION
  • STABILITY
  • CRYSTALS
  • BEHAVIOR

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