  The dynamical aspects of the phonoriton state in highly-photoexcited
semiconductors is studied theoretically. The effect of the exciton-exciton
interaction and nonbosonic character of high-density excitons are taken into
account. Using Green's function method and within the Random Phase
Approximation it is shown that the phonoriton dispersion and damping are very
sensitive to the exciton density, characterizing the excitation degree of
semiconductors.
