Controlling the work function of GaAs by chemisorption of benzoic acid derivatives

Stephane Bastide, Raphael Butruille, David Cahen, Amit Dutta, Jacqueline Libman, Abraham Shanzer, Limin Sun, Ayelet Vilan

Research output: Contribution to journalReview articlepeer-review

91 Scopus citations

Abstract

Control of the work function of GaAs single crystals, under ambient conditions, was achieved by chemisorption of a series of benzoic acid derivatives with varying dipole moments. Quantitative Fourier transform infrared spectroscopy shows that the benzoic acid derivatives bind as carboxylates, via coordination to oxidized Ga or As atoms, with a surface coverage of about one layer and a binding constant of 2.1 104 M-1 for benzoic acid. Contact potential difference measurements reveal that molecules affect the work function by changing the electron affinity while band bending is not affected significantly. The direction of the electron affinity changes depends on the direction of the dipole moments, and the extent of the change increases linearly with the dipole's magnitude. Investigation of the surface composition by X-ray photoelectron spectroscopy shows that the etched surface, onto which the molecules adsorb, is covered by an oxide layer. This may prevent the molecules from affecting band bending.

Original languageEnglish
Pages (from-to)2678-2684
Number of pages7
JournalJournal of Physical Chemistry B
Volume101
Issue number14
DOIs
StatePublished - 3 Apr 1997
Externally publishedYes

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