Regensburg 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 46: Quantum Dots and Wires: Transport
HL 46.6: Vortrag
Mittwoch, 24. März 2010, 15:15–15:30, H17
Spatially resolved flow of ballistic electrons measured by quantized photocurrent spectroscopy — Klaus-Dieter Hof1, Franz J. Kaiser2, •Markus Stallhofer3, Dieter Schuh4, Werner Wegscheider4,5, Peter Hänggi2, Sigmund Kohler2,6, Jörg P. Kotthaus1, and Alexander W. Holleitner1,3 — 1Fakultät für Physik and Center for NanoScience (CeNS), LMU München — 2Institut für Physik, Universität Augsburg — 3Walter Schottky Institut and Physik Department, TUM Garching — 4Institut für Experimentelle und Angewandte Physik, Universität Regensburg — 5Laboratorium für Festkörperphysik, ETH Zürich, Switzerland — 6Instituto de Ciencia de Materiales de Madrid, CSIC, Spain
Quantum point contacts (QPCs) have recently been exploited in very sensitive detection schemes to quantify charge and spin states in nanoscale circuits and to monitor the coherent charge flow in two-dimensional electron gases (2DEGs). Here, we demonstrate the use of GaAs-based QPCs to laterally resolve the ballistic flow of photo-generated electrons in a 2DEG. To this end, electron-hole pairs are optically created in a 2DEG, and the resulting current through an adjacent QPC is measured as a function of the laser spot position. The transmission of photo-generated electrons through the QPC is governed by the quantized energy and momentum values of the electron modes in the QPC. Hereby, the measured photocurrent across the QPC exhibits quantization steps. We observe that photo-generated electrons can ballistically propagate across several micrometers, before they tunnel through the QPC.