Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 52: Heterostructures

HL 52.1: Vortrag

Donnerstag, 25. März 2010, 10:00–10:15, H17

THz Radiation Induced Ratchet Effects in Heterostructures with a Lateral Periodic Potential — •P. Olbrich¹, J. Karch¹, J. Kamann¹, E.L. Ivchenko², R. Ravash¹, T. Feil¹, S.N. Danilov¹, J. Allerdings¹, D. Weiss¹, D. Schuh¹, W. Wegscheider¹, and S.D. Ganichev¹ — ¹THz Center, University of Regensburg, Regensburg, Germany — ²A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia

We report on the observation of the Seebeck ratchet effect measured in semiconductor heterostructures with a one-dimensional lateral potential excited by terahertz (THz) radiation [1]. The one-dimensional grooves in the cap layer obtained by electron beam lithography and subsequent reactive ion etching result in a lateral periodic potential acting on the two dimensional electron gas (2DEG). The photocurrent generation is based on a phase shift which occurs due to the spatially periodic in-plane potential and the spatially modulated light, affecting the local temperature. In addition to the polarization-independent current known as the Seebeck ratchet effect [2], we observed two further contributions being sensitive to the helicity and to the linear polarization of the exciting THz radiation. The effects strongly depend on the symmetry of the one-dimensional lateral potential and its orientation in respect to the crystallographic axes. We show the experimental data described by a microscopic picture and the theoretical analysis, expanding the one of Ref. [2] to the case of polarized radiation.

[1] P. Olbrich et al., Phys. Rev. Lett. 103, 090603 (2009)

[2] Y.M. Blanter, M. Buettiker, Phys. Rev. Lett. 81, 4040 (1998)