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HL: Fachverband Halbleiterphysik

HL 3: III-V-Compounds: GaAs and related Materials

HL 3.6: Talk

Monday, March 14, 2011, 11:30–11:45, POT 151

Carbon doped GaAs/AlGaAs heterostructures with high mobility two dimensional hole gas — •Marika Hirmer¹, Dominique Bougeard¹, Dieter Schuh¹, and Werner Wegscheider² — ¹Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D 93040 Regensburg, Germany — ²Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland

Two dimensional hole gases (2DHG) with high carrier mobilities are required for both fundamental research and possible future ultrafast spintronic devices. Here, two different types of GaAs/AlGaAs heterostructures hosting a 2DHG were investigated. The first structure is a GaAs QW embedded in AlGaAs barrier grown by molecular beam epitaxy with carbon-doping only at one side of the quantum well (QW) (single side doped, ssd), while the second structure is similar but with symmetrically arranged doping layers on both sides of the QW (double side doped, dsd). The ssd-structure shows hole mobilities up to 1.2*10⁶ cm²/Vs which are achieved after illumination. In contrast, the dsd-structure hosts a 2DHG with mobility up to 2.05*10⁶ cm²/Vs. Here, carrier mobility and carrier density is not affected by illuminating the sample. Both samples showed distinct Shubnikov-de-Haas oscillations and fractional quantum-Hall-plateaus in magnetotransport experiments done at 20mK, indicating the high quality of the material. In addition, the influence of different temperature profiles during growth and the influence of the Al content of the barrier Al_xGa_1−xAs on carrier concentration and mobility were investigated and are presented here.