Résumé:

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.