[en] Luminescence dynamics of CdS-doped glasses were measured using up-conversion technique, and they were compared with transmission dynamics. An analysis of the decay curves of luminescence and transmission dynamics has been performed using a multi-exponential fit. Although slower decay component is large in transmission dynamics, it is negligibly small in luminescence dynamics. This difference is observed in all samples investigated, and this may be caused by the difference in relaxation paths of electrons and holes in CdS nanocrystals. Effect of induced absorption on transmission dynamics was examined

[en] We report the results of time-resolved photoluminescence spectroscopy of a double layer quantum dot structure with large spacer distance emitting at 1.3 μm at room temperature. In ultrafast zero-time photoluminescence spectrum, we identified the transitions in GaAs barrier, in wetting layer and in quantum dots. Identical initial rise times give evidence of simultaneous filling of the quantum dot states. The excitation power dependence of photoluminescence dynamics reveals that the carrier dynamics are controlled by radiative recombination and cascade relaxation in quantum dot states. The overall picture of photoluminescence dynamics is in accord with a low concentration of nonradiative recombination channels in the studied structure which demonstrates its application potential. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

[en] Structures with self-assembled InAs quantum dots (QDs) embedded in an AlAs matrix have been studied by steady-state and transient photoluminescence. It has been shown that in contrast to InAs/GaAs QD systems carriers are mainly captured by quantum dots directly from the AlAs matrix, while transfer of carriers captured by the wetting layer far away from QDs to the QDs is suppressed. At low temperatures the carriers captured by the wetting layer are localized by potential fluctuations at the wetting layer interface, while at high temperatures the carriers are delocalized but captured by nonradiative centers located in the wetting layer.

[en] We review the results of our research towards tailoring morphology and optical properties of films consisting of closely-spaced nanocrystals of CdSe and CdS whose optical band-gap can be tuned to cover the whole visible spectral range. On basis of the obtained results, in particular of photoexcited carrier dynamics, we have proposed a microscopic model that describes well the optical properties of the films. We have also showed that the spin relaxation of electrons in these nanocrystalline films is different than that in mutually isolated nanocrystals of the same size. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

[en] We report on the effect of light illumination of nanocrystalline CdSe film during its deposition from chemical bath. We concentrate on the photoexcited carrier dynamics studied by techniques of ultrafast laser spectroscopy. Light illumination by above-band gap light during the growth leads to larger nanocrystals (NCs), which means that the single-step nanocrystal size patterning (with the spatial resolution of tens microns as given by illumination light masking) is possible. Nanocrystal size is a dominating factor, which affects the properties of the films, namely absorption, photoluminescence (PL), and the photoexcited carrier dynamics. The properties are further influenced by the interplay between the interior and surface states of nanocrystals, which is affected by the nanocrystalline size and/or by their surface quality

[en] We study the influence of the wavelength of picosecond excitation pulses on the properties of photoluminescence (PL) in a series of samples of silicon nanocrystals prepared by ion implantation into silica matrix. We observed a gradual change in the behaviour of the PL fast component (spectral shape, decay times, pump-intensity dependence) when tuning the excitation wavelength from 355 to 532 nm. We interpret the results in terms of an interplay between the PL originating from volume states of nanocrystals containing two photoexcited carrier pairs, and the PL due to the silicon oxide states. We discuss also the role of the implant fluence on the PL properties of samples