PH sensitivity of gallium arsenide (GaAs) electrodes functionalized with methyl-mercaptobiphenyl monolayers

Daniel Gassull, Sebastian M. Luber, Abraham Ulman, Michael Grunze, Marc Tornow, Gerhard Abstreiter, Motomu Tanaka

Research output: Contribution to journalArticlepeer-review

Abstract

GaAs electrodes coated with hydrophobic, methyl-mercaptobiphenyl (CH 3-MBP) monolayers exhibited an excellent electrochemical stability. We found that the interface resistance of the chemically functionalized GaAs shows linear relationships with electrolyte pH and bias potential in a reproducible manner. The impedance spectra measured in a wide frequency range (f = 100 kHz to 50 mHz) are analyzed with several equivalent circuit models in a quantitative manner, and the pH sensitivity extrapolated from two linear relationships (35 mV pH-1) can be attributed to the absorption of the OH- ions on the hydrophobic surface.

Original languageEnglish (US)
Pages (from-to)12414-12419
Number of pages6
JournalJournal of Physical Chemistry C
Volume111
Issue number33
DOIs
StatePublished - Aug 23 2007

ASJC Scopus subject areas

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

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