Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.109: Poster

Tuesday, March 23, 2010, 18:30–21:00, Poster B1

Theory of ultrafast carrier relaxation dynamics in graphene — •Torben Winzer, Stefan Butscher, Frank Milde, Andreas Knorr, and Ermin Malić — Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, 10623 Berlin, Germany

We present a microscopic calculation of the relaxation dynamics of photoexcited hot electrons and phonons in graphene.

Using a density matrix formalism, the combination with a tight binding approach for the band-structure and a Born-Markov approximation yields Boltzmann-like equations for interacting electrons and phonons.

In the case of electron-phonon coupling, we find an initial fast carrier cooling on the femtosecond timescale followed by slowed down relaxation dynamics due to the generation of non-equilibrium hot phonons.[1][2]

Even though the relaxation of excited carriers into thermal equilibrium occurs predominantly by energy dissipation through phonons, electron-electron scattering thermalizes the system at the time scale of the electron-phonon interaction.

[1] S. Butscher, F. Milde, M. Hirtschulz, E. Malić, and A. Knorr, Appl. Phys. Lett. 91, 203103 (2007). [2] T. Kampfrath, L. Perfetti, F.Schapper, C. Frischkorn, and M. Wolf, Phys. Rev. Lett. 95, 187403 (2005).