title: Single-Molecule Transport at a Rectifying GaAs Contact.
abstract: In most single- or few-molecule devices, the contact electrodes are simple ohmic resistors. Here we describe a new type of single-molecule device in which metal and semiconductor contact electrodes impart a function, namely, current rectification, which is then modified by a molecule bridging the gap. We study junctions with the structure Au STM tip/X/n-GaAs substrate, where "X" is either a simple alkanedithiol or a conjugated unit bearing thiol/methylthiol contacts, and we detect current jumps corresponding to the attachment and detachment of single molecules. From the magnitudes of the current jumps we can deduce values for the conductance decay constant with molecule length that agree well with values determined from Au/molecule/Au junctions. The ability to impart functionality to a single-molecule device through the properties of the contacts as well as through the properties of the molecule represents a significant extension of the single-molecule electronics "tool-box".
authors.affiliation: Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom.
authors.forename: Andrea
authors.identifier: 0000-0002-8059-0113
authors.initials: A
authors.lastname: Vezzoli
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Brooke
authors.affiliation: Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom.
authors.forename: Nicolò
authors.initials: N
authors.lastname: Ferri
authors.affiliation: Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom.
authors.forename: Simon J
authors.identifier: 0000-0003-3518-9061
authors.initials: SJ
authors.lastname: Higgins
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
authors.forename: Walther
authors.initials: W
authors.lastname: Schwarzacher
authors.affiliation: Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom.
authors.forename: Richard J
authors.identifier: 0000-0002-1446-8275
authors.initials: RJ
authors.lastname: Nichols
keywords: STM; Schottky diode; gallium arsenide; rectification; single molecule junctions