title: Arrays of high quality SAM-based junctions and their application in molecular diode based logic.
abstract: This paper describes a method to fabricate a microfluidic top-electrode that can be utilized to generate arrays of self-assembled monolayer (SAM)-based junctions. The top-electrodes consist of a liquid-metal of GaOx/EGaIn mechanically stabilized in microchannels and through-holes in polydimethylsiloxane (PDMS); these top-electrodes form molecular junctions by directly placing them onto the SAM supported by template-stripped (TS) Ag or Au bottom-electrodes. Unlike conventional techniques to form multiple junctions, our method does not require lithography to pattern the bottom-electrode and is compatible with TS bottom-electrodes, which are ultra-flat with large grains, free from potential contamination of photoresist residues, and do not have electrode-edges where the molecules are unable to pack well. We formed tunneling junctions with n-alkanethiolate SAMs in yields of ∼80%, with good reproducibility and electrical stability. Temperature dependent J(V) measurements indicated that the mechanism of charge transport across the junction is coherent tunneling. To demonstrate the usefulness of these junctions, we formed molecular diodes based on SAMs with Fc head groups. These junctions rectify currents with a rectification ratio R of 45. These molecular diodes were incorporated in simple electronic circuitry to demonstrate molecular diode-based Boolean logic.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. chmnca@nus.edu.sg.
authors.forename: Albert
authors.initials: A
authors.lastname: Wan
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. chmnca@nus.edu.sg.
authors.forename: C S
authors.initials: CS
authors.lastname: Suchand Sangeeth
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. chmnca@nus.edu.sg.
authors.forename: Lejia
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. chmnca@nus.edu.sg.
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. chmnca@nus.edu.sg.
authors.forename: Li
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. chmnca@nus.edu.sg and Solar Energy Research Institute of Singapore (SERIS), 7 Engineering Drive 1 and National University of Singapore, Singapore 117574, Singapore.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Nijhuis