Münster 1999 – scientific programme
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HL: Halbleiterphysik
HL 7: Symposium: Koh
ärenzeffekte in der Halbleiterspektroskopie
HL 7.6: Fachvortrag
Monday, March 22, 1999, 18:30–19:00, Ger
Photoluminescence from large number periodic multiple quantum well structures — •Martin Hübner1, Claudia Ell2, John Prineas2, Peter Brick2, Galina Khitrova2, Hyatt M. Gibbs2, Walter Hoyer3, Macillo Kira3, and Stephan W. Koch3 — 1Universität Göttingen, 4. Physikalisches Institut, Bunsenstr. 13, 37073 Göttingen — 2Optical Sciences Center, University of Arizona, Tucson, AZ 85721, USA — 3Departement of Physics and Material Sciences Center, Phillips University, Renthof 5, 35032 Marburg, Germany
We demonstrate the dominance of cooperative exciton emission from large number periodic multiple quantum well (PQW) structures following nonresonant excitation into the free carrier continuum. We investigate the spectrally resolved excitonic emission at liquid helium temperature from high quality InGaAs/GaAs PQW structures with up to N=100 quantum wells in dependence on the period and the number N of quantum wells. By tuning the period in a range of up to 30% around the excitonic Bragg resonance, we find for N>30 large normal mode splitting and a nonlinear increase in the vertical emission with the number of coupled wells. A crossing of the normal modes around Bragg resonance is observed where the emission is strongly suppressed. The suppressed photoluminescence in Bragg resonance is in contrast to a strong superradiant reemission that follows resonant excitation. The experimental results are analyzed microscopically by extending the semiconductor luminescence equations to the case of PQW structures and are further related to linear and nonlinear pump-probe experiments on the same structures.