  An approach is proposed to determine parameters of homogeneous and
inhomogeneous broadening for reflection lines of quasi-two-dimensional excitons
in semiconductor quantum well structures. A phenomenological model is developed
taking into account fluctuations of the exciton energy which are expected to
cause inhomogeneous broadening of exciton reflectivity lines. This concept is
applied to magneto-optical studies of CdTe/(Cd,Mg)Te single quantum well
heterostructures containing a two-dimensional electron gas. By the analysis of
excitonic reflection spectra in magnetic fields the parameters of homogeneous
and inhomogeneous broadening of the exciton as well as their temperature
dependencies were obtained.
