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(a) The absorption spectra of diameter particles in solution (solid line) and their photoluminescence spectrum (dashed line). (b) Scanning electron microscope image of InAs nanoparticles attached to a GaAs surface by organic linker molecules. The bright spots are the nanodots and the dark background is the GaAs substrate. (c) The IR spectra of GaAs substrate coated with organized organic monolayer of 1,2 ethanedithiol (DT) (dashed line) and the spectra of the GaAs substrate coated with InAs NPs, attached to the substrate by the DT molecules (solid line). The inset presents a scheme of the GaAs substrate coated with InAs and gold nanoparticles attached to the substrate by an organic linker.
The PL spectra of the InAs nanodots for different linker molecules measured at with , laser. The thin line is the PL spectra of the original solution with the NP. The inset shows the integrated signal for two excitation wavelengths of 530 and for different attaching molecules. The integrated signal was normalize to the smallest response at each wavelength.
The photoluminescence spectra obtained from InAs NPs when (a) the GaAs substrate is coated with a mixture of InAs and gold NPs (solid line) or without the gold NPs (dotted line). All NPs are attached to the substrate using decanedithiol as linker. Excitation was performed by a laser. Insert: The dependence of the enhancement factor, due to the gold NPs, on the organic linker. The linkers used are [1,2 ethanedithiol (DET)], [1,10 decanedithiol (DT)], and [l;1,4 benzenedimethanethiol (BDMT)]. The excitation was performed either with 630 or laser. (b) The effect of the excitation wavelength on the enhancement of the photoluminescence signal, measured for GaAs coated with both InAs and gold NPs which are attached to the substrate by decanedithiol. The signal was normalized to the number of photons for each wavelength, and to the increase in the absorption of the system with the decrease of the excitation wavelength (see Fig. 1).
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