Making electrical contacts to molecular monolayers

X. D. Cui, X. Zarate, J. Tomfohr, O. F. Sankey, A. Primak, A. L. Moore, T. A. Moore, D. Gust, Gari Harris, S. M. Lindsay

    Research output: Contribution to journalArticlepeer-review

    304 Citations (Scopus)


    Electrical contacts between a metal probe and molecular monolayers have been characterized using conducting atomic force microscopy in an inert environment and in a voltage range that yields reversible current-voltage data. The current through alkanethiol monolayers depends on the contact force in a way that is accounted for by the change of chain-to-chain tunnelling with film thickness. The electronic decay constant, ßN, was obtained from measurements as a function of chain length at constant force and bias, yielding ßN = 0.8±0.2 per methylene over a ±3 V range. Current-voltage curves are difficult to reconcile with this almost constant value. Very different results are obtained when a gold tip contacts a 1,8-octanedithiol film. Notably, the current-voltage curves are often independent of contact force. Thus the contact may play a critical role both in the nature of charge transport and the shape of the current-voltage curve.
    Original languageEnglish
    Pages (from-to)5-14
    Number of pages10
    Issue number1
    Publication statusPublished - 2002


    • Electronics and devices
    • Surfaces, interfaces and thin films
    • Molecular electronic devices
    • Atomic force microscopy (AFM)
    • AFM


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