The photoluminescence (PL) and PL excitation (PLE) spectra of CdTe/ZnTe asymmetric double quantum well (QW) structures are studied on a series of samples containing two CdTe layers with nominal thicknesses of 2 and 4 monolayers (ML) in the ZnTe matrix. The samples differ in the thickness of the ZnTe spacer between CdTe QWs which is 45, 65 and 75 ML. It has been found that at above-barrier excitation the PL from a shallow QW at sufficiently weak excitation intensities is determined by recombination of hot excitons. It is shown that under these conditions, when PL is excited by lasers with different wavelengths, the ratio of the PL intensities from shallow and deep QWs decreases exponentially with an increase of the initial kinetic energy of hot excitons. It is found that energy relaxation of hot excitons with LO phonon emission determine the shape of the PLE spectrum of shallow QW in the range of exciton kinetic energies up to more than 20 LO phonons above ZnTe bandgap. We have shown that the results obtained are well described by the model of charge and energy transfer between QWs.

The optical properties of series of CdTe/ZnTe heterostructures with two built-in planar CdTe inclusions of thickness 4.0 and 1.5 monolayers are investigated. The temperature behavior of the exciton luminescence intensity at above-barrier and under-barrier excitation depends on the ZnTe barrier thickness which varies from 15 to 55 monolayers. It occurs that the shape of exciton luminescence bands changes strongly under the increasing optical excitation. The excitation luminescence spectra are studied in the temperature range 5 – 80 K.

The photoluminescence and excitation of luminescence spectra of a series of samples containing two CdTe layers D1 and D2 with a nominal thickness of 1.5 and 4 monolayers in a ZnTe matrix were studied. The samples differ in the width of the ZnTe spacer separating the D1 and D2 inserts and constituting 15, 25, 35, 45 and 55 monolayers (samples nos. 1–5, respectively). ZnTe layers are grown on a GaAs substrate by the standard molecular beam epitaxy mode, while CdTe inserts are grown in atomic layer epitaxy mode. It is shown that when the barrier thickness is less than 25 monolayers electronic states in the quantum wells formed by D1 and D2 layers are tunnel-coupled, and only one band is recorded in the emission spectrum, caused by the recombination of excitons in the deep quantum well. At larger thicknesses of the spacer, two bands I1 and I2 are observed in the luminescence spectrum, which are associated with the recombination of excitons in shallow (D1) and deep (D2) wells, respectively. It was found that the intensity ratio I1/I2 significantly depends on the energy and intensity of the excitation. Possible origin of these dependences are discussed.