Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 44: Poster Session I
HL 44.52: Poster
Tuesday, March 15, 2011, 18:00–21:00, P3
Tuning the Two-Dimenional Hole Gas Density in CdMnTe Quantum Wells by Near-surface Doping and Photoexcitation — •Franziska Fricke1, Christian Kehl1, Georgy Astakhov1, Jean Geurts1, Wolfgang Ossau1, Yuri Kusrayev2, Kyrill Kavokin2, Tomek Wojtowicz3, and Grzegorz Karczewski3 — 1Universität Würzburg, Phys. Inst., EP3, 97074 Würzburg, Germany — 2Ioffe Institute, RAS, 194021 St. Petersburg, Russia — 3Institute of Physics, PAN, 02668 Warsaw, Poland
P-doped CdMnTe quantum wells are known to exhibit a trend towards ferromagnetism, induced by the two-dimensional gas of heavy holes (2DHG). One way to supply a 2DHG to the quantum well is p-type doping from surface states by tunneling through a very thin capping layer. Tuning of the 2DHG density is achieved by variation the cap layer thickness and by photogeneration of charge carriers.
We present photoluminescence (PL) and magneto-PL studies on CdMnTe/CdMgTe quantum wells using resonant quantum well excitation and above-barrier excitation. The 2DHG is characterized essentially by the intensity and spectral position of the positively charged exciton (trion X+) with respect to the neutral exciton (X0). We describe the observed 2DHG behaviour consistently by a model based on specific tunneling times of electrons and holes, which depend on the cap thickness and the power and photon energy of the optical excitation radiation.