Photoreflectance line shape in quantum-confined semiconductor systems: the case of dilute nitrides

Photoreflectance technique has been extensively applied for studying the optical properties of quantum-confined semiconductor systems and for a long time the excitonic character of the intersubband transitions has been commonly accepted. The case of dilute nitrides deserves particular interest because of the unusual asymmetric aspect of their line shape, sometimes reported in the literature for quantum well related transitions. The origin of the asymmetric line shape is clarified, meanwhile showing how it can be used to acquire fine informations on the exciton binding energy and to investigate the N-induced variation of the electron eective mass in this class of semiconductor compounds.