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Stable anchoring chemistry for room temperature charge transport through graphite-molecule contacts

Rudnev, A V; Kaliginedi, V; Droghetti, A; Ozawa, H; Kuzume, A; Haga, M A; Broekmann, P; Rungger, I (2017) Stable anchoring chemistry for room temperature charge transport through graphite-molecule contacts. Science Advances, 3 (6). e1602297

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An open challenge for single molecule electronics is to find stable contacts at room temperature with a well-defined conductance. While common coinage metal electrodes pose fabrication and operational problems due to the high mobility of the surface atoms, here we demonstrate how molecules covalently grafted onto mechanically robust graphite/graphene substrates overcome these limitations. To this aim, we explore for the first time the effect of the anchoring group chemistry on the charge transport properties of graphite/molecule contacts by means of the scanning tunneling microscopy break-junction technique and ab initio simulations. Molecules adsorbed on graphite only via van der Waals interactions have a conductance that decreases exponentially upon stretching the junctions, while the molecules bonded covalently to graphite have a single well defined conductance and yield contacts of unprecedented stability at room temperature. We also demonstrate a strong bias dependence of the single molecule conductance induced by the graphite electrodes, which varies over more than one order of magnitude at low bias voltages, and show that the direction of tunneling current rectification can be tuned by anchoring group chemistry. Combined with the prospect of new functionalities due to a strongly bias dependent conductance, such covalent contacts are ideal candidates for next generation molecular electronics devices.

Item Type: Article
Keywords: graphene; quantum transport; quantum devices; theoretical modelling; DFT; molecules on surfaces
Subjects: Quantum Phenomena > Nanophysics
Divisions: Quantum Science
Identification number/DOI: 10.1126/sciadv.1602297
Last Modified: 06 Feb 2018 12:47
URI: http://eprintspublications.npl.co.uk/id/eprint/7682

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