Séminaire : A 10-nm sized molecular electronics platform for applied and fundamental molecular property measurements

Klaus LEIFER (Departement of Engineering Science, University of Uppsala, Sweden) fera une présentation de ses travaux le mercredi 20 mars à 14h en salle 40 du bâtiment 40 au campus du CNRS de Cronenbourg (23 rue du Loess 67200 Strasbourg).

Title: A 10-nm sized molecular electronics platform for applied and fundamental molecular property measurements

Abstract : The field of single and few molecule electronics has seen great progress in electrical contacting of molecules, chemical protocols and measurement set-ups. Here, we show a new way to establish molecular-metal junctions in a nanoelectrode-molecule-nanoparticle junction platform [1]. The device allows for measurements of electrical properties of a few molecules which is a sufficiently small number to obtain the electronic signature related to single molecules bound in this junction. The molecule-nanoparticle junctions are established by di-electrophoretic trapping of octane-dithiol functionalised nanoparticles (5nm), where the dangling thiol group is protected using trityl molecules [2]. The subsequent removal of the trityl molecules allows the thiol-group to bond to the closest metal surface so that a network of conductive pathways is established between the electrodes spaced by 20nm. This procedure enabled the establishment of reproducible molecule-metal junctions resulting in the reduction of the spread of resistance histograms on the devices to less than one order of magnitude. This enabled us to carry out inelastic tunnel spectroscopy (IETS) measurements. Quantitative modelling of these junctions by density functional theory calculations as well as quantum transport calculations allowed very good fits of the model to our experimental results revealing several vibrational transitions in the IETS spectra. Furthermore we obtain that typical conductive channels contain 4-6 molecule-nanoparticle junctions. This platform is thus prepared for sensor applications and we will present first sensing results.
[1] T. Blom, K. Welch, M. Stromme, E. Coronel, K. Leifer, Nanotechn. 18, 285301, 2007; S. H. M. Jafri, T. Blom, A. Wallner, K. Welch, M. Stromme, H. Ottosson and K. Leifer, J. Microelectr. Eng., 88, 2629, 2011.
[2] A. Wallner,H.Jafri,T.Blom,A.Gogol,J.Baumgartner,K.Leifer,H.Ottosson,Langmuir27,9057,2011.