Berlin 2012 – scientific programme
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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: Talk
Thursday, March 29, 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).