RESONANT BRILLOUIN-SCATTERING FROM POLARITONS IN ZNSE GAAS EPITAXIAL LAYERS/

The first observation of resonant Brillouin scattering in an epitaxial ly grown semiconductor layer is reported. The material is ZnSe grown b y metalorganic vapor phase epitaxy on a GaAs substrate. We have studie d the spectra and kinetics of the emission occurring under resonant op tical excitation in the exciton-polariton region by a tunable picoseco nd laser. The Brillouin scattering data are used to analyze in detail the effect of strain in the sample and determine the exchange splittin g of the exciton states, which is found in quantitative agreement with the reflectivity.