Making electrical contact to single molecules

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Abstract
We are interested in the characterization of electron transport phenomenon through single (bio)molecules. A prerequisite for electrical measurements is the contacting of molecules in the nanometer range. This paper describes various steps toward this goal, starting from statistically distributed molecules (namely, microtubules) adsorbed on a microstructured surface. Monitored by scanning force microscopy and video-enhanced microscopy, adsorption parameters were studied and optimized, including protein-mediated adsorption, induced orientation, and controlled desorption. Line structures connecting the adsorbed molecules to prestructured electrodes were created by means of electron beam-induced deposition (EBD) in a scanning electron microscope. It is shown how such EBD lines can be used as masks for the structuring of metal contacts, and an electrical characterization of these contacts is given.