Photoluminescence, its temperature dependence, and photoluminescence excitation spectra of InAs quantum dots embedded in asymmetric InxGa1−xAs∕GaAs quantum wells [dots in a well (DWELL)] have been investigated as a function of the indium content x (x=0.10–0.25) in the capping InxGa1−xAs layer. The asymmetric DWELL structures were created with the aim to investigate the influence of different barrier values at the quantum dot (QD)/quantum well interface on the photoluminescence thermal quenching process. The set of rate equations for the two stage model for the capture and thermal escape of excitons in QDs are solved to analyze the nature of thermal activation energies for the QD photoluminescence quenching process. The two stage model for exciton thermal activation was confirmed experimentally in the investigated QD structures as well. The localization of nonradiative defects in InAs∕InGaAs DWELL structures is discussed on the base of comparison of theoretical and numerically calculated (fitting) results.

Photoluminescence (PL), its temperature and excitation power dependences, and PL excitation spectra have been investigated in InAs quantum dots (QDs) embedded in In0.15Ga0.85As/GaAs quantum wells (QWs) as a function of QD density. The QD density varied from 1.1×1011 down to 1.3×1010 cm−2 with the increase in QD growth temperature at the molecular beam epitaxy processing. A set of rate equations for exciton dynamics (relaxation into QWs and QDs, and thermal escape) has been solved to analyze the mechanism of PL thermal quenching in studied structures. Three stages have been revealed in thermal decay of the PL intensity of InAs QDs. Presented mathematical analysis provides the explanations of the mechanism of PL thermal decay as well as the peculiarities of PL excitation power dependences and PL excitation spectra. A variety of activation energies of PL thermal decay and the localization of nonradiative defects in InGaAs/GaAs QW structures with different InAs QD density are discussed as well.

The paper presents the results of photoluminescence (PL) and Raman scattering studies of non-conjugated and bio-conjugated CdSe/ZnS core-shell quantum dots (QDs). The commercial CdSe/ZnS QDs used are characterized by color emission with maxima at 605-610 nm (2.03-2.05 eV). PL spectra of non-conjugated QDs are the superposition of PL bands related to exciton emission in the CdSe core (2.03-2.05 eV) and to hot electron-hole emission via defect states at the CdSe/ZnS interface (2.37 and 2.68 eV). QD conjugation was performed with biomolecules -- the antihuman interleukin 10 antibody (antihuman IL10). The PL spectra of bio-conjugated QDs have been changed dramatically: only one PL band related to exciton emission in the CdSe core was detected in bio-conjugated QDs. To explain this effect a model has been proposed which assumes that the QD bio-conjugation process is accompanied by the recharging of acceptor-like interface states at the CdSe/ZnS interface. A comparative analysis of normalized PL spectra of non-conjugated CdSe/ZnS QDs with different intensities of interface state PL has confirmed the proposed electron-hole recombination model in QDs.