Excitons in CdTe/ZnTe heterostructure with atomically thin CdTe layers

Heterostructures with atomically thin double quantum wells based on CdTe/ZnTe are investigated by optical spectroscopy (photoluminescence and reflectivity methods) as a function of temperature and density of excitation. Heavy and light exciton luminescence lines are observed with comparable intensities and different temperature behaviors (they cross each other at about 65 degrees K). All these features agree with a complete calculation that takes into account both a very small chemical band offset for such monolayer CdTe inclusions in the ZnTe matrix (namely, 2%), and, consequently, the importance of Coulombic interaction in these double quantum wells.