LO-PHONONS AND EXCITONS IN (CD,ZN)TE BASED QUANTUM-WELLS

We review the exciton properties of (Cd, Zn)Te based quantum well stru ctures with the emphasis on LO phonon-exciton interactions. At low tem peratures LO phonon emission is an important energy relaxation mechani sm for excitons. Low spectral diffusion due to localization results in sharp line spectra. Spectral relaxation within localised exciton band s through LO phonon emission is described. The distinction between res onant Raman scattering and the sharp lines observed in these materials is made. At room temperature the width of the exciton resonance depen ds on the interaction between excitons and the-thermal population of L O phonons. This interaction can be modified by changing the structure. LO phonon scattering causes rapid exciton ionization, yet free excito n luminescence can still be observed. The relative contributions to th e absorption saturation due to free carriers and excitons is examined on a femtosecond time scale.