Dresden 2009 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 48: Poster 2
HL 48.16: Poster
Thursday, March 26, 2009, 15:00–17:30, P2
Characterization of Spatially Indirect Excitons in Coupled Quantum Wells — Georg Schinner1, •Markus Stallhofer1, Katarzyna Kowalik1, Dieter Schuh2, Werner Wegscheider2, Alexander Holleitner1,3, and Jörg Kotthaus1 — 1Fakultät für Physik and Center for NanoScience, LMU Munich, Geschwister-Scholl-Platz 1, D-80539 München, Germany — 2Institut für Angewandte und Experimentelle Physik, Universität Regensburg, Universitätsstraße 31, D-93040 Regensburg, Germany — 3TU Munich, Walter Schottky Institut, Am Coulombwall 3, 85748 Garching, Germany
In coupled quantum wells photo-generated and spatially indirect excitons can be widely manipulated via an externally applied voltage. The quantum-confined Stark effect (QCSE) results in a large enhancement of excitonic lifetime and a red shift in energy. A number of photoluminescence (PL) experiments have been performed on indirect excitons in GaAs double quantum wells (DQW) that were tuned via a metallic top gate. We characterize an especially designed InGaAs DQW-heterostructure with PL and transmission experiments at liquid Helium temperatures. The QCSE was measured with PL and determined to be around 150 meV/V, a very high value compared to literature. Therefore, it is possible to achieve a large energy shift by applying relatively low voltages in our sample. In a confocal microscope we perform transmission experiments on the indirect excitons in a field-effect structure with a semitransparent titanium top gate. They allow investigating electron-hole pairs under resonant excitation.