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Photoluminescence excitation spectra are obtained for a large set of strained CdTe/Cd&, Zn Te single-quantum-well samples, as a function of well thickness. The experimental spectra are reproduced by an accurate variational exciton envelope function, expanded in products of electron and hole subbands. An analytical approximation for the exciton envelope function, we11 suited for thin films with finite confinement potentials, is also given. The good agreement obtained between theory and experiment for both methods strongly supports the concept of center-of-mass quantization for this quantumwell system in the thickness range from 180 to 1000 A.

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Durch langsame Zersetzung von aus HF und ZrOCIQ ° 8 H2O gebildeten Fluorozirkoniumkomplexen in Gegenwart von Hydroxymethan‐ bzw. Benzolphosphonsäure oder Triethylphosphat werden die mikrokristallinen Verbindungen (I)‐(III) gebildet.

Exciton binding energies and optical response in quantum wells and in multiple quantum wells of GaAs/In Gay As/GaAs are computed by a variational envelope-function procedure using the four-band model and the simpler two-band model. The eKect of hydrostatic and uniaxial strain are considered from a virtual-crystal stress Hamiltonian. The physical parameters used for the alloy (In Gaz As) are obtained by interpolating the parameter values of pure materials (GaAs, InAs). We verify that band-oHset values in the range of 0.30 -0.45 give exciton states and optical response in good agreement with experiments. The light-hole exciton energy is also well reproduced by theory and results are very close to the continuum states of the well, its binding energy being due to the attraction of the electron, localized inside the well.