Berlin 2015 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
HL: Fachverband Halbleiterphysik
HL 3: Graphene: THz, NIR and transport properties (with O/TT)
HL 3.1: Talk
Monday, March 16, 2015, 09:30–09:45, ER 270
Ratchet effects in graphene with a lateral periodic potential — •P. Olbrich1, J. Kamann1, J. Munzert1, M. König1, L.E. Golub2, L. Tutsch1, J. Eroms1, F. Fromm3, Th. Seyller3, D. Weiss1, and S.D. Ganichev1 — 1University of Regensburg, Regensburg, Germany — 2Ioffe Institute, St. Petersburg, Russia — 3Technical University of Chemnitz, Germany
We report on the observation of terahertz (THz) radiation induced photocurrents in (a) epitaxially grown and (b) exfoliated graphene with a lateral periodic potential. The samples were covered with an insolating layer and a sequence of asymmetrically spaced thin/thick metallic stripes. While in the reference of sample (a) under normal incidence of THz radiation no photosignal was observed, the illumination of the lateral periodic potential resulted in pronounced photosignals, consisting of polarization dependent and independent contributions. In case of sample (b) the thin/thick metallic stripes act as a dual top gate structure to vary the potential profile and a back gate allows to change the carrier type and density of the sample. Here, the photocurrent reflects the degree of asymmetry induced by different top gate potentials and even vanished for a symmetric profile. Moreover, around the Dirac point the photocurrent shows strong oscillation. We discuss the experimental data, taking into account the calculated potential profile, near field effects of light scattering and the theoretical model [1, 2].
[1] E. L. Ivchenko and S. D. Ganichev, JETP Lett. 93, 673 (2011).
[2] P. Olbrich et al., Phys. Rev. B 83, 165320 (2011).