  We investigate the effect of a two dimensional electron gas on the linear
optical properties of CdTe quantum wells. We evidence experimentally the high
energy tail of the exciton and charged exciton resonances which depends on
electron concentration. Based on that, we show that the scattering of electrons
with excitons and charged excitons is needed to be included in the matrix
transfer calculations to describe the reflectivity spectra. We demonstrate by
time-resolved reflectivity experiments the importance of electron distribution
in the resonance lineshapes.
