Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 9: Poster I

HL 9.100: Poster

Montag, 27. März 2006, 15:15–17:45, P3

Experimental and Numerical Investigations of the Terahertz Photoconductivity of QH-Systems — •Gabriel Vasile^1,2, Christian Stellmach¹, Yuri Vasilyev³, Alexander Hirsch¹, Günter Hein⁴, Rolf Gerhardts⁵, and Georg Nachtwei¹ — ¹Institut für Angewandte Physik, TU-Braunschweig, D-38106 Braunschweig, Deutschland — ²National Institute of Research-Development for Cryogenics and Isotopic Technologies, Ro-1000 Rm. Valcea, Romania — ³A.F. Ioffe Physical Technical Institute, Ru-194021 St. Petersburg, Russia — ⁴Physikalisch-Technische Bundesanstalt, D-38116 Braunschweig, Deutschland — ⁵Max Planck Institut für Festkörperforschung, D-70569 Stuttgart, Deutschland

We present measurements of the Terahertz (THz) photoconductivity of quantum-Hall systems in GaAs/AlGaAs heterostructures with meander and Corbino geometries by using a pulsed p-Ge laser as the THz source (1.7 to 2.5 THz). The photoconductivity versus the magnetic field shows a two-fold structure: one peak at the cyclotron frequency and the others near the minima of the conductivity around the filling factor 2. In order to understand the features revealed by our measurements we perform calculations of the absorption (Joule heating) for different magnetic fields and laser frequencies. To do so we first calculate the dynamic and static conductivities within the Drude and self-consistent Born approximations. The quantum effect seems to be smeared out at high frequencies. This work shows important conclusions for the development of tunable THz detectors.