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Münster 1999 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 12: Poster I

HL 12.82: Poster

Montag, 22. März 1999, 14:00–18:00, Z

Optical properties of ZnSe/ZnMgSSe single quantum wells — •C. Rudamas1,2, U. Neukirch1,3, and J. Gutowski11Institut für Festkörperphysik, Universität Bremen, P.O. Box 330440, 28334 Bremen — 2present address: Departamento de Física Aplicada, Universidad de Valencia, C./ Dr. Moliner 50, 46100 Burjassot (Valencia), Spain — 3present address: Lawrence Berkeley National Laboratory, Materials Sciences Division, MS 2-346, 1 Cyclotron Road, Berkeley, CA 94720, USA

Exciton-related photoluminescence of ZnSe/Zn1−yMgySxSe1−x single quantum wells grown by molecular beam epitaxy has been studied by means of optical spectroscopy. The well thickness of the samples are 5, 10 and 20 nm and the Mg and S contents of the barriers amount to 0.22 and 0.16, respectively. Photoluminescence (PL) and reflection spectra obtained at 2 K allow the identification of the heavy (HH) and light hole (LH) exciton resonances. A two-oscillator polariton model is succesfully used for the theoretical description of the reflection spectra. Quantization of the polariton wave vector within the ZnSe well leads to allowed propagating modes, which are clearly resolved experimentally.
Up to the fifth quantum state of the HH exciton resonance could be observed in the thickest sample by photoluminescence excitation (PLE) measurements, which are also in agreement with the results of the polariton model.
The exciton binding energies, the band offsets and the energy position of the 2s-HH resonance are obtained using an analytical model calculation developed in a fractional-dimensional space.
Temperature and excitation dependent PL, together with the above described measurements, show that a peak on the low energy side of the HH resonance could be attributed to a negatively charged exciton.

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