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1,322 results on '"Godlewski, M"'

77. Role of electron traps in the excitation and de-excitation mechanism of Yb3+ in InP

Author

Tsimperidis, I., Gregorkiewicz, T., Ammerlaan, C.A.J., Godlewski, M., Scholz, F., and Lambert, B.

Subjects
Ytterbium -- Research, Indium -- Research, Physics
Abstract

Excitation and de-excitation of a triply ionized Yb ion are influenced by the introduction of the electron trap level in InP by Yb doping. There is no donor-acceptor pair recombination energy transfer to the Yb ions. The formation of Yb-bound excitation systems causes excitation of the characteristic Yb photoluminescent processes.

Published
1995

80. Optical recombination mechanisms in Eu2+-doped CaS and SrS thin films

Author

Swiatek, K., Godlewski, M., Niinisto, L., and Leskela, M.

Subjects
Thin films -- Research, Photoluminescence -- Research, Physics
Abstract

The study of the excitation and deexcitation mechanisms of Eu(2+) emission in CaS:Eu and SrS:Eu thin films reveals that the internal transitions within the positively-changed ions and resonant energy transfer between different Eu centers cause the ion luminescence excitation at low temperatures. The luminescence decay kinetics and photoluminescence spectra are investigated with constant and varying temperature. The efficiency of the emission is influenced by the electron transfer between different europium ions over the conduction band of the host lattice.

Published
1993

82. Si/ZnO nanorods/Ag/AZO structures as promising photovoltaic plasmonic cells.

Author

Placzek-Popko, E., Gwozdz, K., Gumienny, Z., Zielony, E., Pietruszka, R., Witkowski, B. S., Wachnicki, Ł., Gieraltowska, S., Godlewski, M., Jacak, W., and Liann-Be Chang

Subjects
OPTICAL properties of zinc oxide, NANORODS, NANOSTRUCTURED materials, P-type semiconductors, PHOTOLUMINESCENCE, SILVER nanoparticles
Abstract

The test structures for photovoltaic (PV) applications based on zinc oxide nanorods (NRs) that were grown using a low-temperature hydrothermal method on p-type silicon substrates (100) covered with Ag nanoparticles (NPs) were studied. The NPs of three different diameters, i.e., 5-10 nm, 20-30 nm, and 50-60 nm, were deposited using a sputtering method. The morphology and crystallinity of the structures were confirmed by scanning electron microscopy and Raman spectroscopy. It was found that the nanorods have a hexagonal wurtzite structure. An analysis of the Raman and photoluminescence spectra permitted the identification of the surface modes at 476 cm-1 and 561 cm-1. The presence of these modes is evidence of nanorods oriented along the wurtzite c-axis. The NRs with Ag NPs were covered with a ZnO:Al (AZO) layer that was grown using the low-temperature atomic layer deposition technique. The AZO layer served as a transparent ohmic contact to the ZnO nanorods. The applicability of the AZO layer for this purpose and the influence of the Ag nanoparticles on the effectiveness of light acquisition by such prepared PV cells were checked by reflectance and transmittance measurements of the AZO/glass and AZO/NPs/glass reference structures. Based on these studies, the high-energy transmittance edge was assigned to the ZnO energy gap, although it is blueshifted with respect to the bulk ZnO energy gap because of Al doping. It was also shown that the most optimal PV performance is obtained from a structure containing Ag nanoparticles with a diameter of 20-30nm. This result is confirmed by the current-voltage measurements performed with 1-sun illumination. The structures show a plasmonic effect within the short wavelength range: the PV response for the structure with Ag nanoparticles is twice that of the structure without the nanoparticles. However, the influence of the Ag nanoparticle diameters on the plasmonic effect is ambiguous. [ABSTRACT FROM AUTHOR]

Published
2015
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