Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 88: Quantum Dots and Wires: Transport Properties IV (mainly Double Dots and Point Contacts)

HL 88.4: Vortrag

Donnerstag, 29. März 2012, 17:15–17:30, EW 202

Magnetic focusing of ballistic photocurrents in mesoscopic circuits — Markus Stallhofer¹, •Christoph Kastl¹, Christoph Karnetzky¹, Dieter Schuh³, Werner Wegscheider⁴, Gerhard Abstreiter¹, Jörg Kotthaus², and Alexander Holleitner¹ — ¹Walter Schottky Institut and Physik-Department, TU München — ²Fakultät für Physik and Center for NanoScience (CeNS), LMU München — ³Institut für Experimentelle und Angewandte Physik, Universität Regensburg — ⁴Laboratorium für Festkörperphysik, ETH Zürich, Switzerland

We exploit GaAs-based quantum point contacts (QPCs) as mesoscopic detectors for analyzing the flow of photogenerated electrons in a two-dimensional electron gas (2DEG) [1]. At moderate, perpendicularly applied magnetic fields, we resolve circular electron trajectories. We extract the cyclotron radius and the electron momentum of the photogenerated electrons at varying magnetic fields and irradiation intensities. The extracted values surprisingly exceed the ones derived from a single-particle cyclotron motion. With the help of Monte Carlo simulations, this deviation is related to the effects of electron-electron scattering on the propagation of the photo-excited electrons.

[1] K.-D. Hof et al., Nano Letters, 10, 3836 (2010).