Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 82: Nanostructures at Surfaces: Graphene and Other Aspects
O 82.9: Vortrag
Mittwoch, 22. März 2017, 18:00–18:15, REC/PHY C213
Electronic and optical properties of ultra-thin graphene nanoribbons — •Boris Senkovskiy1, Danny Haberer2, Alexander Fedorov1, Markus Pfeiffer3, Sayed Alavi3, Nicolae Atodiresei4, Vasile Caciuc4, Klas Lindfors3, Felix Fischer2, and Alexander Grüneis1 — 1Institute of Physics II, University of Cologne, Germany — 2Department of Chemistry, University of California at Berkeley, Berkeley, USA — 3Institute for Physical Chemistry, University of Cologne, Germany — 4Peter Grünberg Institute and Institute for Advanced Simulation, Jülich, Germany
The present work demonstrates that electronic and optical properties of ultra-thin graphene nanoribbons are strikingly different from its 2D or 3D counterparts. A semiconductor-to-metal transition in armchair graphene nanoribbons of N=7 carbon atoms width causes drastic changes in the electronic system. By using angle-resolved photoemission spectroscopy of lithium doped nanoribbons, a quasiparticle band gap renormalization from 2.4 eV to 2.1 eV is observed. Reaching high doping levels (0.05 electrons/atom), it is found that the effective mass of the conduction band carriers increases by a factor of four to a value equal to the free electron mass. This giant increase in the effective mass by doping can have palpable impact on the electronic properties of the system. Having carried out the bubble transfer of massively aligned nanoribbons from the gold to the insulating substrate we investigate the optical properties of the material. It is shown that incorporation of sp3 defects induces polarized photoluminescence from intrinsically 'dark' graphene nanoribbons.