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The solar cells efficiency may be improved by better exploitation of the solar spectrum, making use of the down-conversion mechanism, where one high energy photon is cut into two low energy photons. The choice of the matrix is a crucial point to obtain an efficient down-conversion process with rare-earth ions. When energy transfer between rare earth ions is(More)
Fabrication of confined structures, where light can be confined over nano or micro scale region is fantastic challenge for nano-science based technologies. Manufacture of such structures has become possible due to the opportunity delivered by nanotechnology, which opens the way to the study of new functional artificial materials and plasmonic structures,(More)
Porous silicon (PSi) samples were prepared by electrochemical anodisation of silicon on insulator layers. Structural and optical properties of prepared samples were investigated by Raman and photoluminescence (PL) spectroscopy and field emission scanning electron microscopy (FE-SEM). The anodisation of silicon on insulator layers was performed by(More)
Silver colloids were produced by chemical reduction of silver salt (silver nitrate, AgNO<sub>3</sub>) solution. As a reducing agents trisodium citrate, sodium borohydride, ascorbic acid, PVP (Polyvinylpyrrolidone) and glucose were used. The characters of silver nanoparticles were investigated using UV-Vis spectrophotometer, dynamic light scattering (DLS),(More)
Tellurite glasses are known as a promising material for optical fiber fabrication thanks to the specific optical and thermo-mechanical features. This paper shows tellurite glasses doped with different concentrations of various rare earth ions characterized by Raman spectroscopy. Especial attention was paid to the low frequency `Boson peak' and the modes of(More)
Technologically modified g-GeS<sub>2</sub>(TiVj) glasses prepared by melt quenching from different temperatures (T<sub>i</sub>) and with different cooling rates (Vj) were studied using Raman spectroscopy and model calculations. Differential Raman spectra {I<sub>R</sub>GeS<sub>2</sub>(T<sub>i</sub>V<sub>1</sub>)-I<sub>R</sub>GeS2(T<sub>2</sub>V<sub>1</sub>)}(More)