Résumé:

Quantum-well ground and excited states are observed using wavelength-modulated reflectivity in InxGa1-xAs/AlyGa1-yAs single-quantum-well structures. To account for the dependence of their energies on indium and aluminum concentrations, we find that it is necessary to include the coupling between the light-hole GAMMA(8) valence band and the spin-orbit split-off GAMMA(7) valence band. The calculation is performed using a two-band envelope-function approximation, and good agreement with experiment is obtained.