Excitons in tunnel coupled CdTe and (Cd,Mn)Te quantum wells

Abstract

The photoluminescence (PL) from structures containing Cd0.95Mn0.05Te and CdTe quantum wells (QWs) separated by a narrow (1.94 nm) barrier was studied. The PL lines of comparable intensities from several possible exciton states were observed simultaneously at energy distances substantially exceeding kT. This means that the energy transfer in the studied systems is slower than the radiative recombination of the confined excitons. For the CdTe QW width of about 8.7–9 nm, indirect excitons with the electron and heavy hole chiefly localized in the CdTe and Cd1−xMnxTe QWs, respectively, were detected in the magnetic field. These indirect excitons have PL energy of about 10–20 meV above the PL line of the direct excitons in the CdTe QW. The observation of the PL from the indirect excitons which are not the lowest excitations in the structure is a distinctive feature of the system.Photoluminescence intensity dependence on the energy and the magnetic field.