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 88.5: Vortrag

Donnerstag, 29. März 2012, 17:30–17:45, EW 202

Ballistic photocurrents at the presence of electron-electron scattering — Markus Stallhofer¹, •Christoph Karnetzky¹, Marcel Brändlein¹, Christoph Kastl¹, Dieter Schuh³, Werner Wegscheider⁴, 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 demonstrate that GaAs-based quantum point contacts (QPCs) can be employed to resolve the non-equilibrium dynamics of photo-generated charge carriers in a mesoscopic circuit [1]. To this end, electron-hole pairs are optically created in a two-dimensional electron gas (2DEG) and the resulting current through an adjacent QPC is measured as a function of the laser spot position. We particularly investigate the characteristic spatial decay length of the photocurrent as a function of the optical excitation power and the excitation energy. We identify two transport regimes, dominated either by the effects of electron-electron scattering or the formation of an optically induced Quasi-Fermi level.

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