Dresden 2017 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 14: Poster: Two-Dimenaional Materials and Topological Insulators

HL 14.2: Poster

Montag, 20. März 2017, 14:00–18:00, P2-OG3

Polarized hot carrier photoluminescence in graphene — •Thomas Danz, John H. Gaida, Claus Ropers, and Sascha Schäfer — IV. Physical Institute – Solids and Nanostructures, University of Göttingen, Germany

The thermalization of photogenerated hot charge carriers in graphene leads to photoluminescence (PL) at wavelengths far away from that of the exciting pump laser [1,2]. Although a strongly anisotropic carrier distribution is created by linearly polarized optical excitation [3], the polarization properties of the emerging PL have not been reported yet.

In this contribution, we report the anisotropic polarization response of the hot carrier PL in graphene and discuss a possible coherent contribution to the incoherent emission. On the basis of spectral interferometry, we find that any coherent contribution to the emission must be smaller than 4% of the total PL signal. By comparing the experimentally measured degree of polarization to a microscopic model of the carrier dynamics based on Boltzmann rate equations, we are able to determine a time-scale of 12± 2 fs for the ultrafast momentum relaxation in graphene [4].
[1] C. H. Lui et al., Phys. Rev. Lett. 105, 127404 (2010)

[2] W. Liu et al., Phys. Rev. B. 82, 081408 (2010)

[3] E. Malic et al., Appl. Phys. Lett. 101, 213110 (2012)

[4] Th. Danz et al., in preparation.