Control of the pH-dependence of the band edges of Si(111) surfaces using mixed methyl/allyl monolayers

Erik Johansson, Shannon W. Boettcher, Leslie E. O'Leary, Andrey D. Poletayev, Stephen Maldonado, Bruce S. Brunschwig, Nathan S. Lewis

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31 Citations (Scopus)


The open-circuit potentials of p-Si/((MV2+/MV+) (aq)) junctions with Si(111) surfaces functionalized with H-, CH 3-, CH2CHCH2-, or mixed CH3-/CH 2CHCH2- monolayers have been investigated as the solution pH was changed from 2.5 to 11. The pH sensitivity of the open-circuit potentials, and therefore the band-edge positions, was anticorrelated with the total fraction of Si atop sites that were terminated by Si-C bonds. This behavior is consistent with the hypothesis that the non Si-C terminated atop sites were initially H-terminated and were unstable to oxide growth under aqueous conditions with the oxidation-product inducing a pH-dependent dipole. Metal-semiconductor junctions between Hg and CH3-, CH 2CHCH2-, or mixed CH3-/CH2CHCH 2-terminated n-Si(111) surfaces formed rectifying Hg/Si Schottky junctions and exhibited mutually similar barrier-heights (̃0.9 V), suggesting similar magnitudes and direction of the surface dipoles on all of these functionalized surfaces.

Original languageEnglish
Pages (from-to)8594-8601
Number of pages8
JournalJournal of Physical Chemistry C
Issue number17
Publication statusPublished - May 5 2011

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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