Charge-State Assignment of Nanoscale Single-Electron Transistors from their Current-Voltage Characteristics

Bart Limburg, James O. Thomas, Jakub K. Sowa, Kyle Willick, Jonathan Baugh, Erik M. Gauger, G. Andrew D. Briggs, Jan A. Mol, Harry L. Anderson

Research output: Contribution to journalArticle

2 Citations (Scopus)
2 Downloads (Pure)

Abstract

The electronic and magnetic properties of single-molecule transistors depend critically on the molecular charge state. Charge transport in single-molecule transistors is characterized by Coulomb-blocked regions in which the charge state of the molecule is fixed and current is suppressed, separated by high-conductance, sequential-tunneling regions. It is often difficult to assign the charge state of the molecular species in each Coulomb-blocked region due to variability in the work-function of the electrodes. In this work, we provide a simple and fast method to assign the charge state of the molecular species in the Coulomb-blocked regions based on signatures of electron-phonon coupling together with the Pauli-exclusion principle, simply by observing the asymmetry in the current in high-conductance regions of the stability diagram. We demonstrate that charge-state assignments determined in this way are consistent with those obtained from measurements of Zeeman splittings. Our method is applicable at 77 K, in contrast to magnetic-field-dependent measurements, which generally require low temperatures (below 4 K). Due to the ubiquity of electron-phonon coupling in molecular junctions, we expect this method to be widely applicable to single-electron transistors based on single molecules and graphene quantum dots. The correct assignment of charge states allows researchers to better understand the fundamental charge-transport properties of single-molecule transistors.
Original languageEnglish
Pages (from-to)14820-14827
Number of pages8
JournalNanoscale
Volume11
Issue number31
Early online date22 Jul 2019
DOIs
Publication statusPublished - 21 Aug 2019

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