Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 21: Transport: Graphene and Carbon Nanotubes

TT 21.6: Vortrag

Dienstag, 26. Februar 2008, 17:00–17:15, EB 202

Photocurrent and radiation induced suppression of transport in graphene — Konstantin Efetov^1,2, Mikhail Fistul¹, and •Sergey Syzranov¹ — ¹Theoretische Physik III, Ruhr-Universität Bochum, 44801 Bochum, Germany — ²L.D. Landau Institute for Theoretical Physics RAS, 119334 Moscow, Russia

We study the ballistic transport in graphene subject to the coordinate dependent potential U(x) and irradiated by monochromatic electromagnetic field (EF). The resonant interaction of quasi-particles with an external radiation opens dynamical gaps in their spectrum, resulting in a strong modification of current-voltage characteristics of graphene junctions. The gaps’ values are proportional to the amplitude of EF. We obtain that the quasi-particle transmission in diverse junctions, e.g. unipolar (p-p or n-n) junctions, is determined by the tunneling through the gap, and can be fully suppressed for large enough radiation powers. In the case of a p-n junction, as the height of the potential U(x) is larger than the photon energy, the directed current (photocurrent) flows through the junction without any dc bias voltage applied. Such a photocurrent arises as a result of inelastic quasiparticles’ tunneling assisted by one- or two-photon absorption. We calculate current-voltage characteristics of diverse graphene based junctions and estimate their parameters necessary for the experimental observation of the photocurrent and transmission suppression.