title: Nano-fabrication of molecular electronic junctions by targeted modification of metal-molecule bonds.
abstract: Reproducibility, stability and the coupling between electrical and molecular properties are central challenges in the field of molecular electronics. The field not only needs devices that fulfill these criteria but they also need to be up-scalable to application size. In this work, few-molecule based electronics devices with reproducible electrical characteristics are demonstrated. Our previously reported 5 nm gold nanoparticles (AuNP) coated with ω-triphenylmethyl (trityl) protected 1,8-octanedithiol molecules are trapped in between sub-20 nm gap spacing gold nanoelectrodes forming AuNP-molecule network. When the trityl groups are removed, reproducible devices and stable Au-thiol junctions are established on both ends of the alkane segment. The resistance of more than 50 devices is reduced by orders of magnitude as well as a reduction of the spread in the resistance histogram is observed. By density functional theory calculations the orders of magnitude decrease in resistance can be explained and supported by TEM observations thus indicating that the resistance changes and strongly improved resistance spread are related to the establishment of reproducible and stable metal-molecule bonds. The same experimental sequence is carried out using 1,6-hexanedithiol functionalized AuNPs. The average resistances as a function of molecular length, demonstrated herein, are comparable to the one found in single molecule devices.
authors.affiliation: Applied Materials Science, Department of Engineering Sciences, Uppsala University, Box 534, Uppsala SE-75121, Sweden.|Department of Electrical Engineering, Mirpur University of Science and Technology, Mirpur Azad Jammu and Kashmir 10250, Pakistan.
authors.forename: S Hassan M
authors.initials: SH
authors.lastname: Jafri
authors.affiliation: Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-75120, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Löfås
authors.affiliation: Applied Materials Science, Department of Engineering Sciences, Uppsala University, Box 534, Uppsala SE-75121, Sweden.
authors.forename: Tobias
authors.initials: T
authors.lastname: Blom
authors.affiliation: Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala SE-75123, Sweden.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wallner
authors.affiliation: Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-75120, Sweden.
authors.forename: Anton
authors.initials: A
authors.lastname: Grigoriev
authors.affiliation: Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-75120, Sweden.|Applied Material Physics, Department of Materials and Engineering, Royal Institute of Technology (KTH), Stockholm SE-10044, Sweden.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ahuja
authors.affiliation: Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala SE-75123, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Ottosson
authors.affiliation: Applied Materials Science, Department of Engineering Sciences, Uppsala University, Box 534, Uppsala SE-75121, Sweden.
authors.forename: Klaus
authors.initials: K
authors.lastname: Leifer