POLARIZED INTERACTING EXCITON GAS IN QUANTUM-WELLS AND BULK SEMICONDUCTORS

We develop a theory to calculate exciton binding energies of both two- and three-dimensional spin polarized exciton gases within a mean held approach. Our method allows the analysis of recent experiments showin g the importance of the polarization and intensity of the excitation l ight on the exciton luminescence of GaAs quantum wells. We study the b reaking of the spin degeneracy observed at high exciton density (5 x 1 0(10) cm(2)). Energy level splitting between spin +1 and spin -1 is sh own to be due to many-body interexcitonic exchange while the spin rela xation time is controlled by intraexciton exchange.