We have studied the reflectance and photoluminescence spectra of a series of GaAs/AlAs superlattices grown by molecular beam epitaxy on GaAs (001) substrates exactly oriented or slightly misoriented. It is shown that the substrate misorientation has spectacular effects on the excitonic transition properties, strongly depending on the misorientation direction. The anisotropic dependencies of the exciton broadening and the emission line Stokes-shift are analyzed on the basis of a qualitative understanding of the interface structures.

We report on studies of the optical properties of a series of (Ga,In)As-AlAs thin strained-layer multiple quantum wells and superlattices submitted to high uniaxial stress perpendicular to the growth axis of the structures. Samples having both type-I and type-II configurations for their conduction-band to valence-band potential profiles have been studied. Explanation of the experimental data has been made in the context of an envelope-function approach, which explicitly takes into account the mixing of the upper valence-band states with the split-off valence-band states. The inclusion of spin-dependent deformation potentials is necessary to interpret the values of the zero-stress energies as well as to explain their behavior as a function of the external stress.

We report on some magneto-photoluminescence experiments on CdTe/Cd1-xMnxTe superlattices, which allow the observation of the type-I --> type-II transition induced by the giant Zeeman effect of the semimagnetic barrier. The study of the magnetic field, for which the transition occurs, as a function of temperature leads to a determination of the band offset. In addition, several observations about defect luminescence are reported and several specific properties of CdTe/Cd1-xMnxTe structures are discussed: strain effects on the band offset, exciton binding energy, spin-flip scattering mechanism.

This work reports on growth, characterization, and calculation of the electronic structure of GaAs-(Ga,In)P quantum wells, where the two semiconductors share neither a common anion nor a common cation. Metal organic molecular-beam epitaxy was the growth method that we used. The composition of the disordered alloy was close to 50 at. % indium. We have determined the valence-band offset in such structures. We have found DELTA-E(c)/DELTA-E(v) = 0.4, and have calculated the influence of the spin-orbit split-off states on the light-hole confinement. We found that these deep valence states significantly reduce the light-hole confinement.

Optical properties involving energy states that are not localized in the wells of superlattices are investigated. We show how the symmetry properties of these unconfined states can be easily understood by a perturbative calculation of a near-free-electron superlattice. The selection rules are found to be dependent on the layer thicknesses. The optical transitions of an (In,Ga)As-GaAs strained superlattice are calculated using a tight-binding model. We demonstrate that a transition previously considered forbidden is, in reality, symmetry allowed.

This paper describes both experimental and theoretical demonstrations of an unexpected symmetry of the carrier envelope functions associated with resonant states in superlattices. The experiments reveal a mixing between the first light-hole (confined state) and the second heavy-hole (unconfined state) produced by application of a uniaxial stress in crossed configuration with the growth axis of a (Ga,In)As-GaAs superlattice. The theoretical aspects of the physics are addressed via both envelope function and tight-binding calculations.

Recently, III-V/II-VI single and double heterostructures have attracted much attention for device applications. The first demonstration of metal organic vapour phase epitaxy (MOVPE) of a GaAs/ZnSe/GaAs double heterostructure is reported. The influence of the ZnSe layer on the top GaAs layer is discussed from photoluminescence and reflectivity results.