Molecular conductance measurements through printed Au nanodots

Gold pads with ∼100 nm diameter are imprinted on self-assembled monolayers of alkane dithiols of different lengths using nanotransfer printing. The pads are contacted by conductive atomic force microscope tips, and electron transport was measured as a function of force. Atomic scale topography at the metal-molecule interface is essential to describe the conductance-stress relationship. A finite force (1-10 nN) deforms devices resulting in two competing effects: (a) a larger contact area and (b) deformation of the interfacial bonds and/or tilting of the molecules. The estimated conductance of molecules is significantly smaller than results suggested in previous experiments and calculations.