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HL: Fachverband Halbleiterphysik
HL 33: Spin-dependent Transport I
HL 33.9: Vortrag
Dienstag, 15. März 2011, 12:30–12:45, POT 251
Remanent spin injection and spin relaxation in quantum dot light emitting diodes — •Henning Soldat1, Mingyuan Li1, Nils C. Gerhardt1, Arne Ludwig2, Frank Stromberg3, Werner Keune3, Heiko Wende3, Andreas D. Wieck2, Dirk Reuter2, and Martin R. Hofmann1 — 1Lehrstuhl für Photonik und Terahertztechnologie, Ruhr-Universität Bochum, D-44780 Bochum — 2Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum — 3Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universität Duisburg-Essen, D-47048 Duisburg
The study of spin-controlled optoelectronic devices has been a field of intensive research over the past few years. We investigate spin injection in remanence into InAs quantum dot (QD) light emitting diodes (LEDs). Our samples are spin LEDs with a Fe/Tb injector with out-of-plane remanent magnetization and a MgO tunnel barrier at the ferromagnetic metal/semiconductor interface to overcome the conductivity mismatch. The active region is an ensemble of InAs QDs. Intrinsic GaAs layers of variable thickness have been implemented between this active region and the spin injector to investigate the influence of transport path length on spin polarization. We have measured the circular polarization of the LED emission in remanence. By investigating the different injection path lengths for the samples we have determined the spin diffusion length in undoped GaAs along with the spin polarization at the injector interface. Additionally, the spin injection efficiency at the MgO tunnel barrier has been investigated.