Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 3: Heterostructures
HL 3.5: Vortrag
Montag, 23. März 2009, 11:15–11:30, BEY 154
Dynamics of Dipolar Excitons in Coupled GaAs Quantum Wells — •Xaver Vögele1, Dieter Schuh2,3, Werner Wegscheider2, Alexander Holleitner1,3 und Jörg Kotthaus1 — 1Center for NanoScience, Ludwig-Maximilians-Universität, D-80539 München — 2Institut für Angewandte und Experimentelle Physik, Universität Regensburg, D-93040 Regensburg — 3Technische Universität München, Walter Schottky Institut, 85748 Garching
Photo-generated electron-hole pairs in double quantum well devices can be manipulated both in lifetime and position via a mesoscopic voltage-controlled electrostatic landscape. The quantum-confined Stark effect allows us to create long-living indirect excitons[1].
Recently, we demonstrated a novel electrostatic trap for indirect excitons in coupled GaAs quantum wells embedded in a field-effect device. There, the indirect excitons are trapped in the quantum wells just below the perimeter of SiO2-layers, which are sandwiched between the surface of the GaAs heterostructure and a semitransparent metallic top gate[2].
Here, we present time resolved measurements on the dynamics of the excitons inside the trap. We find that the expansion of the trapped excitons occurs on a much shorter time-scale than in the untrapped case. We attribute this to effective screening of quantum well disorder.
Financial support: Center for NanoScience (CeNS), the Nanosystems Initiative Munich (NIM), and the DFG Project KO 416/17.
[1] A. Gärtner et al. Appl. Phys. Lett 89, 052108 (2006). [2] A. Gärtner et al. Phys. Rev. B 76, 085304 (2007).