posted 12 Aug 2014, 00:12 by Lisbeth Kirk Mynster
Rasmus B. Christensen1 ,Thomas Frederiksen2,3, Mads Brandbyge1
1DTU Nanotech, Center for Nanostructured Graphene (CNG), DK-2800 Kgs. Lyngby, Denmark
2Donostia International Physics Center (DIPC) -- UPV/EHU, Donostia-San Sebastian, Spain
3IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
Graphene Nano-ribbons(GNR) are a potential candidate for molecular wires with tailored conductance properties. However, characterization of edge passivation or structural/chemical defects is challenging especially after device fabrication. Inelastic electron tunneling spectroscopy(IETS), serves as a way of preforming nondestructive characterization yielding vibrational fingerprints of a range of defects. In order to interpret experiments, theoretical modelling of the inelastic signals, as a consequence of electron–phonon scattering, in the electronic current is of interest. Contrary to metallic contacts, for the carbon systems the electronic states vary on the energy scale of the vibrational frequencies necessitating calculations which go beyond the otherwise successful LOE-WBA . This method also enable studies of IETS on gated graphene. On this poster we present the modeling of IETS signals for GNRs with a selection of relevant defects. We use non-equilibrium Greens functions in combination with DFT calculations to calculate all parameters from first principles.
 J.T. Lü, R. B. Christensen, G. Foti, T. Frederiksen, T. Gunst and M. Brandbyge "Efficient calculation of inelastic vibration signals in electron transport: Beyond the wide-band approximation", Phys. Rev. B 89, 081405(R), 2014.
Rasmus Bjerregaard Christensen is currently a PhD student in the group of Mads Brandbyge at DTU Nanotech. His work concerns theoretical studies of the interplay between electronic current and phonon dynamics in nano-electronics using non-equilibrium Greens functions in combination with DFT calculations. He got his master in theoretical physics, from the Niels Bohr Institute, studying cuprate superconductors.