Relaxation of excitons in coherently strained CdTe/ZnTe quantum wells

The relaxation kinetics of photogenerated excitons have been investigated in coherently strained CdTe/ZnTe quantum wells. Picosecond time-resolved luminescence spectra clearly display several replicas of the excitation pump due to the relaxation of photogenerated excitons in the CdTe well assisted by the emission of optical phonons. The luminescence replicas merge into a single broadband at a time typically larger than 300 ps, revealing spatial diffusion of excitons in the well. We study the gradual localization of photogenerated excitons from the decay of the hot luminescence.