title: Mechanical and charge transport properties of alkanethiol self-assembled monolayers on a au(111) surface: the role of molecular tilt.
abstract: The relationship between charge transport and mechanical properties of alkanethiol self-assembled monolayers (SAMs) on Au(111) films has been investigated using an atomic force microscope with a conductive tip. Molecular tilts induced by the pressure applied by the tip cause stepwise increases in film conductivity. A decay constant beta = 0.57 +/- 0.03 A-1 was found for the current passing through the film as a function of tip-substrate separation due to this molecular tilt. This is significantly smaller than the value of approximately 1 A-1 found when the separation is varied by changing the length of the alkanethiol molecules. Calculations indicate that, for isolated dithiol molecules S-bonded to hollow sites, the junction conductance does not vary significantly as a function of molecular tilt. The impact of S-Au bonding on SAM conductance is discussed.
authors.affiliation: Materials Sciences Division, University of California Berkeley, Berkeley California 94720, USA.
authors.forename: Yabing
authors.initials: Y
authors.lastname: Qi
authors.forename: Imma
authors.initials: I
authors.lastname: Ratera
authors.forename: Jeong Y
authors.initials: JY
authors.lastname: Park
authors.forename: Paul D
authors.initials: PD
authors.lastname: Ashby
authors.forename: Su Ying
authors.initials: SY
authors.lastname: Quek
authors.forename: J B
authors.initials: JB
authors.lastname: Neaton
authors.forename: Miquel
authors.initials: M
authors.lastname: Salmeron