PICOSECOND DYNAMICS OF HOT BIEXCITONS IN CUCL UNDER WEAK EXCITATION REGIME

The time-resolved spectra of the biexciton luminescence are observed in CuCl at 2 K under the weak excitation of the Z1,2 exciton absorption band. It is found that the temporal change of the spatial density distribution of the exciton polariton is essentially important for the analysis of the biexciton dynamics when the biexciton is generated by the collision of two excitons. The intraband relaxation time of hot biexciton by acoustic phonon is obtained to be about 100 ps and the lifetime of biexciton to be less than 90 ps. The lifetime is comparable with the luminescence decay time of the biexciton generated under the two-photon resonant excitation.