Time-resolved spectroscopy of biexciton luminescence in ${\mathrm{Zn}}_{\mathit{x}}$${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$Se-${\mathrm{ZnS}}_{\mathit{y}}$${\mathrm{Se}}_{1\mathrm{-}\mathit{y}}$ multiple quantum wells

The radiative lifetime of biexcitons in ${\mathrm{Zn}}_{\mathit{x}}$${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$Se-${\mathrm{ZnS}}_{\mathit{y}}$${\mathrm{Se}}_{1\mathrm{-}\mathit{y}}$ multiple quantum wells has been studied by means of time-resolved luminescence spectroscopy under high-density excitation. It is shown that the rise of the biexciton luminescence becomes more rapid with increasing excitation energy density and that the biexciton luminescence decays with a double exponential form. It is found that the decay-time constant of the faster-decay component in the double-exponential decay corresponds to the radiative lifetime of the biexciton. Its value is about 6 ps at 2 K and is about one-seventh of that in bulk ZnSe (∼40 ps).