Parts | Days | Selection | Search | Downloads | Help
HL: Halbleiterphysik
HL 12: Poster I
HL 12.82: Poster
Monday, March 22, 1999, 14:00–18:00, Z
Optical properties of ZnSe/ZnMgSSe single quantum wells — •C. Rudamas1,2, U. Neukirch1,3, and J. Gutowski1 — 1Institut 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.