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HL: Fachverband Halbleiterphysik

HL 28: THz Physics

HL 28.2: Talk

Monday, March 14, 2011, 17:45–18:00, POT 51

Time-resolved ultrafast photocurrents and terahertz generation in electrically contacted, freely suspended graphene — •Leonhard Prechtel¹, Li Song², Nadine Erhard¹, Dieter Schuh³, Werner Wegscheider⁴, and Alex W. Holleitner¹ — ¹Walter Schottky Institut and Physik-Department, TU München — ²Fakultät für Physik and Center for NanoScience (CeNS), LMU, München — ³Institut für Experimentelle und Angewandte Physik, Universität Regensburg — ⁴Laboratorium für Festkörperphysik, ETH Zürich

We investigate the ultrafast photocurrent dynamics of freely suspended graphene contacted by metal electrodes in the time-domain. At the graphene-metal interface we demonstrate, that built-in electric fields give rise to an ultrafast photocurrent with a FWHM of only a few ps. This suggests the use of graphene for ultrafast photodetectors and photoswitches. We further detect a photo-thermoelectric current with a decay time of about 0.2 ns. We also show that in optically pumped freely suspended graphene plasmon oscillations and terahertz-radiation are efficiently generated.