ULTRAFAST RELAXATION OF PHOTOEXCITED CARRIERS IN SEMICONDUCTOR SUPERLATTICES

The differential transmission signal (DTS) of a pump-probe transmissio n experiment on the GaAs/AlGaAs superlattice is calculated using the e ffective semiconductor Bloch equation and by assuming that the main me chanism of the relaxation for a low carrier density is the carrier LO- phonon scattering. From the theoretical analysis of the DTS signal, th e intrasubband and intersubband relaxation times of the carriers which are excited optically to the second miniband are estimated. The resul ts are compared to those of recent femtosecond pump-probe experiments on the GaAs/AlGaAs superlattice.