title: Single-molecule conductance in atomically precise germanium wires.
abstract: While the electrical conductivity of bulk-scale group 14 materials such as diamond carbon, silicon, and germanium is well understood, there is a gap in knowledge regarding the conductivity of these materials at the nano and molecular scales. Filling this gap is important because integrated circuits have shrunk so far that their active regions, which rely so heavily on silicon and germanium, begin to resemble ornate molecules rather than extended solids. Here we unveil a new approach for synthesizing atomically discrete wires of germanium and present the first conductance measurements of molecular germanium using a scanning tunneling microscope-based break-junction (STM-BJ) technique. Our findings show that germanium and silicon wires are nearly identical in conductivity at the molecular scale, and that both are much more conductive than aliphatic carbon. We demonstrate that the strong donor ability of C-Ge σ-bonds can be used to raise the energy of the anchor lone pair and increase conductance. Furthermore, the oligogermane wires behave as conductance switches that function through stereoelectronic logic. These devices can be trained to operate with a higher switching factor by repeatedly compressing and elongating the molecular junction.
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Su
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States.
authors.forename: Haixing
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Vivian
authors.initials: V
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Madhav
authors.initials: M
authors.lastname: Neupane
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States.
authors.forename: Arunabh
authors.initials: A
authors.lastname: Batra
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Rebekka S
authors.initials: RS
authors.lastname: Klausen
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Bharat
authors.initials: B
authors.lastname: Kumar
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Steigerwald
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.|Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States.
authors.forename: Latha
authors.initials: L
authors.lastname: Venkataraman
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Colin
authors.initials: C
authors.lastname: Nuckolls