Direct View of Hot Carrier Dynamics in Graphene

Jens Christian Johannsen, Søren Ulstrup, Federico Cilento, Alberto Crepaldi, Michele Zacchigna, Cephise Cacho, I. C. Edmond Turcu, Emma Springate, Felix Fromm, Christian Raidel, Thomas Seyller, Fulvio Parmigiani, Marco Grioni, and Philip Hofmann
Phys. Rev. Lett. 111, 027403 – Published 9 July 2013
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Abstract

The ultrafast dynamics of excited carriers in graphene is closely linked to the Dirac spectrum and plays a central role for many electronic and optoelectronic applications. Harvesting energy from excited electron-hole pairs, for instance, is only possible if these pairs can be separated before they lose energy to vibrations, merely heating the lattice. Until now, the hot carrier dynamics in graphene could only be accessed indirectly. Here, we present a dynamical view on the Dirac cone by time- and angle-resolved photoemission spectroscopy. This allows us to show the quasi-instant thermalization of the electron gas to a temperature of 2000K, to determine the time-resolved carrier density, and to disentangle the subsequent decay into excitations of optical phonons and acoustic phonons (directly and via supercollisions).

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  • Received 18 April 2013

DOI:https://doi.org/10.1103/PhysRevLett.111.027403

© 2013 American Physical Society

Authors & Affiliations

Jens Christian Johannsen1, Søren Ulstrup2, Federico Cilento3, Alberto Crepaldi3, Michele Zacchigna4, Cephise Cacho5, I. C. Edmond Turcu5, Emma Springate5, Felix Fromm6, Christian Raidel6, Thomas Seyller6, Fulvio Parmigiani3,7, Marco Grioni1, and Philip Hofmann2,*

  • 1Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
  • 2Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
  • 3Sincrotrone Trieste, 34149 Trieste, Italy
  • 4IOM-CNR Laboratorio TASC, Area Science Park, 34012 Trieste, Italy
  • 5Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
  • 6Institut für Physik, Technische Universität Chemnitz, 09126 Chemnitz, Germany
  • 7Department of Physics, University of Trieste, 34127 Trieste, Italy

  • *philip@phys.au.dk

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Issue

Vol. 111, Iss. 2 — 12 July 2013

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