Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 52: Graphene: Characterization and devices (HL, jointly with MA, O, TT)

HL 52.8: Vortrag

Mittwoch, 13. März 2013, 11:30–11:45, H17

Terahertz generation in freely suspended graphene — •Andreas Brenneis¹, Leonhard Prechtel¹, Helmut Karl², Dieter Schuh³, Werner Wegscheider⁴, Li Song⁵, Pulickel Ajayan⁶, and Alexander W. Holleitner¹ — ¹Walter Schottky Institut and Physik-Department, TU München, Germany — ²Institute of Physics, University of Augsburg, Germany — ³Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany — ⁴Laboratorium für Festkörperphysik, ETH Zürich, Switzerland — ⁵University of Science and Technology of China — ⁶Rice University, Houston, Texas, USA

We report on THz generation and picosecond photocurrents in freely suspended bilayers of graphene [1]. The graphene layers are connected to coplanar strip lines which serve as source and drain contacts. A pump laser pulse excites charge carrier in the graphene. The resulting charge carrier dynamics couple to the strip line circuit and propagate along the strip line. With a probe laser pulse focused onto an on-chip photo switch, the propagating signal is read out via a third contact with a picosecond time resolution. By varying the delay of the probe pulse relative to the pump pulse, the optoelectronic signal can be measured time-resolved. We discuss the generation of THz radiation, ultrafast displacement currents, and thermoelectric currents within the optically excited graphene. Financial support by the ERC-grant NanoREAL is acknowledged.

References: [1] L. Prechtel, L. Song, D. Schuh, P. Ajayan, W. Wegscheider, A.W. Holleitner, Nature Comm. 3, 646 (2012).