Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 60: Poster II: Optical Properties, incl. Photonic Crystals and Ultrafast Phenomena

HL 60.16: Poster

Donnerstag, 25. März 2010, 18:00–20:00, Poster D1

Optical Conductivity of Graphene in the THz Range — •Alexander Urich, Juraj Darmo, Daniel Dietze, Michael Martl, and Karl Unterrainer — Vienna University of Technology, Photonics Institute, 1040 Vienna, Austria

A striking feature of single layer graphene is the linearity of its band structure around the points K and K' in k-space. This fact is theoretically expected to result in strong interaction of graphene with terahertz (THz) radiation under certain conditions and thus makes this material very interesting for the THz spectral range.

Absorption in single layer graphene is dominated by interband processes for high frequencies leading to a universal behavior of the optical conductivity measured in the visible spectrum, whereas intraband processes play the dominant role for low frequencies. Depending on temperature and Fermi energy a transition from a frequency regime with dominant interband contribution to a regime with dominant intraband contribution is predicted to occur in the THz spectral range resulting in a strong frequency dependence of the optical conductivity.

In this contribution we present optical conductivity measurements of an isolated graphene monolayer by means of THz time domain spectroscopy. Due to the poor availability of high quality large scale graphene samples we chose an on-chip approach involving a coplanar waveguide structure for THz generation and detection.