We investigated plasmon-assisted enhancement of emission from silicon nanoparticles (ncs-Si) embedded into porous SiO
x
matrix in the 500- to 820-nm wavelength range. In the presence in the near-surface region of gold nanoisland film, ncs-Si exhibited up to twofold luminescence enhancement at emission frequencies that correspond to the plasmon resonance frequency of Au nanoparticles. Enhancement of the photoluminescence (PL) intensity was attributed to coupling with the localized surface plasmons (LSPs) excited in Au nanoparticles and to increase in the radiative decay rate of ncs-Si. It has been shown that spontaneous emission decay rate of ncs-Si modified by thin Au film over the wide emission spectral range was accelerated. The emission decay rate distribution was determined by fitting the experimental decay curves to the stretched exponential model. The observed increase of the PL decay rate distribution width for the Au-coated nc-Si-SiO
x
sample in comparison with the uncoated one was explained by fluctuations in the surface-plasmon excitation rate.PACS78. 67. Bf; 78.55.-m
Abstract. Investigated in this paper have been polarization properties of photoluminescence in solid and porous nc-Si−SiO x light emitting structures passivated in HF vapor. These structures were produced by thermal vacuum evaporation of silicon monoxide SiO powder onto polished c-Si substrates. After annealing in vacuum for 15 min at the temperature 975 °C, SiO x films were decomposed to SiO 2 with Si nanoclusters embedded in the oxide matrix. Comparison of polarizations, inherent to exciting light and that of film photoluminescence, enabled to find the polarization memory effect in the passivated structures. In anisotropic porous nc-Si−SiO x samples, obtained by oblique deposition in vacuum, there is also well-defined orientation dependence of the PL polarization degree in the sample plane. This dependence is related to the orientation of oxide nanocolumns that form the structure of the porous layer. The above effects are associated with transformation during etching in HF the symmetric Si nanoparticles to asymmetric elongated ones.
The effect of Cu doping and calcination temperatures on photoluminescence (PL) spectra and XRD patterns of Y-stabilized ZrO2 powders was studied. The PL spectra of (Y,Cu) codoped samples showed the presence of two main PL components peaked at about 630 and 540 nm in the most samples. The increase of calcination temperature results in the non-monotonic variation of total PL intensity as well as the somewhat changes in PL spectra. The temperature increase from 500°C to 600°C results in the increase of total PL intensity and can be ascribed to the increase of crystallinity degree. The next PL intensity decrease with temperature rise up to 800-900°C is attributed to the appearance of non-radiative recombination centers, probably Zr3+. Their number decrease after annealing at 900-1000°C due to phase transformation from tetagonal to monoclinc as well as the appearance of additional green band can be the reason of consequence PL intensity increase.
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