Berlin 2005 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Halbleiterphysik
HL 63: Ultrakurzzeitph
änomene
HL 63.5: Vortrag
Mittwoch, 9. März 2005, 11:45–12:00, TU P-N201
Nonlinear transmission and pump-and-probe experiments on ZnSe/ZnSSe heterostructures — •Iryna Kudyk1, Ilja Rückmann1, Jürgen Gutowski1, Stefan Schumacher2, Gerd Czycholl2, and Frank Jahnke2 — 1Institut für Festkörperphysik, Universität Bremen, POB 330440, D-28334 Bremen — 2Institut für Theoretische Physik, Universität Bremen, POB 330440, D-28334 Bremen
The energy position of polariton modes in the optical spectra of semiconductor nanostructures depends on the layer thickness due to quantization of the electron-hole motion. Therefore, ZnSe nanostructures with layer thicknesses of about 20 nm are appropriate objects for studies of polariton effects. The polariton modes in a 20 nm ZnSe layer are initially characterised with linear transmission spectroscopy. Furthermore, the polariton and biexcitonic properties are investigated in nonlinear transmission and in pump-and-probe experiments. 110 fs pulses are generated by a frequency-doubled mode-locked Ti:sapphire laser. The spectral position of the pulses is adjusted to exclusively excite the hh1 to hh3 polariton modes and the corresponding biexciton. For the experiments the polarization state of the excitation pulses is chosen to be either linear or circular by use of Pockelscells. In nonlinear transmission experiments with linear polarization of the excitation pulses as well as in pump-and-probe experiments with contra-circular polarization the biexciton with a binding energy of 4.3 meV is clearly observed. The presented experimental results are in good agreement with numerical calculations based on a microscopic theory.