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HL: Fachverband Halbleiterphysik

HL 83: Poster: Graphene (with MA/O)

HL 83.10: Poster

Mittwoch, 2. April 2014, 17:00–20:00, P1

The Effect of the Chemical Potential of Graphene on THz Detection — •Markus Göthlich¹, Fathi Gouider¹, André Müller², Yuri B. Vasilyev³, and Georg Nachtwei¹ — ¹Institut für Angewandte Physik, Technische Universität Braunschweig, Mendelssohnstraße 2, D-38106 Braunschweig — ²Physikalisch Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig — ³A.F.Ioffe Physical Technical Institute, RU-194021 St.Petersburg, Russia

One particular fact about graphene is its remarkable Landau quantization E_n = sgn(n) √Δ² + 2 ℏ e v_F² |n| B with n being the Landau level (LL) index. This would allow a transition at 2.4 THz (corresponding to an energy of about 10 meV) to happen at a magnetic field as low as 0.2 T. But theoretical investigations show the opening of a bandgap and a high chemical potential in epitaxial graphene on Si-face SiC due to graphene–substrate interactions. On the other hand our calculations—based on Gusynin et al. Phys. Rev. Lett. 98, 157402 (2007)—show that at high chemical potential the photoresponse can only be observed at higher magnetic fields of some Tesla. Gating is difficult due to the insolating behaviour of SiC substrate on the one hand and THz intransparency of top gates on the other hand. Therefore our aim is to design a new sample geometry that allows the manipulation of the chemical potential of the graphene while not blocking the THz radiation before reaching the detector.