Exciton transfer dynamics in CdTe/(Cd,Zn) Te asymmetric double quantum well structures

Abstract Time-resolved photoluminescence measurements on CdTe/(Cd,Zn)Te asymmetric double quantum wells (ADQWs) with electron and hole confinement potentials of some tens of meV are reported. The carrier transfer from the narrow into the wide well is evidenced by photoluminescence decay times of the narrow well as short as a few picoseconds. The observed tunneling times depend strongly upon the barrier and well widths of the investigated samples which determine the relative position of spatial direct and cross exciton transitions. Very efficient tunneling is found in ADQWs in which the transfer of spatial direct excitons under emission of LO phonons is possible. In any case, one has to consider excitonic rather than single particle electron or hole states in order to explain the observed behaviour of the tunneling times.