Synthesis and Photoluminescence of Weblike Agglomeration of Silica Nanoparticles

El‐Shall, M. Samy; Li, S.; Turkki, T.; Graiver, Daniel; Pernisz, Udo C.; Baraton, Marie‐Isabelle

doi:10.1021/j100051a001

Cited by 61 publications

(57 citation statements)

References 3 publications

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“…Other workers have observed both blue and orange bands in time-resolved PL from porous silicon 28 and during atmospheric oxidation of uncapped SiNCs ͑steady-state PL͒. [29][30][31] These studies are consistent with an interpretation that the blue emission is associated with Si oxides and that the orange PL is particle size dependent and derives from the quantum confinement effect in Si. Blue emission has been observed from Si and C implanted in SiO 2 matrices 32 and from carbon-plasma-implanted porous silicon, 33 but the orange emission of porous silicon disappeared after implantation.…”

supporting

confidence: 82%

“…The second possibility is much more likely because our previous Fourier transform infrared 15 ͑FTIR͒ and photoemission spectroscopy 11 data show that there is a small amount of oxide present in the samples. The works of others 28,30 also support this interpretation. When nanocrystalline Si is oxidized, the Si-Si or Si-O-Si bonds are likely to weaken or break in many places because of the stress at the Si/ SiO 2 interface.…”

mentioning

confidence: 53%

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Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

Chao

Houlton

Horrocks

et al. 2006

Applied Physics Letters

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The origin and stability of luminescence are critical issues for Si nanocrystals which are intended for use as biological probes. The optical luminescence of alkyl-monolayer-passivated silicon nanocrystals was studied under excitation with vacuum ultraviolet photons ͑5.1-23 eV͒. Blue and orange emission bands were observed simultaneously, but the blue band only appeared at low temperatures ͑Ͻ175 K͒ and with high excitation energies ͑Ͼ8.7 eV͒. At 8 K, the peak wavelengths of the emission bands were 430± 2 nm ͑blue͒ and 600± 2 nm ͑orange͒. The orange and blue emissions originate from unoxidized and oxidized Si atoms, respectively. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2216911͔Silicon nanostructures have attracted great interest since the observation of their efficient visible photoluminescence at room temperature in the early 1990s. 1-4 Silicon nanocrystals ͑SiNCs͒ are potential building blocks of future electronic and photonic devices. They also have promise as luminescent labels in biological applications, 5-9 because they show red-orange luminescence at small particle sizes ͑ca. 2 nm diam͒ and are not expected to show some aspects of the toxicity of cadmium-based semiconductors. However, the stability of SiNCs towards O 2 and H 2 O is a concern. Recently, several groups, including ourselves, have prepared alkyl-passivated silicon nanocrystals. [5][6][7][8][9][10][11][12][13][14][15][16] These are SiNCs whose surface is capped by a monolayer of saturated hydrocarbon molecules and anchored to the Si core via covalent Si-C bonds. Although the particles contain a little oxide from their preparation, the alkyl monolayer protects the Si core and they are not oxidized further under ambient conditions. 6 The reaction used to prepare the capping monolayer is sufficiently general to allow manipulation of the chemical functionality on the particle surface, e.g., for synthesis of DNA strands. 6 However, it is also important to characterize the physical properties, especially the luminescence, of these systems because the utility of the particles depends on their luminescence upon insertion into biological cells.Compared to the generally weak IR luminescence of bulk silicon ͑observed at low temperatures͒, the efficiency of photoluminescence ͑PL͒ from Si nanostructures is strongly increased due to the greater overlap of the electron and hole wave functions and the decrease in efficiency of nonradiative pathways. 17,18 A few electronic structure calculations on alkylated SiNCs have been made using density functional methods: these calculations include Si 29 clusters passivated with CH 3 or CH 2 ͑Ref. 19͒ and, more recently, alkyl monolayers up to C 4 H 9 on cluster sizes from Si 20 to Si 142 . 20 Theoretical work suggests that the band gap of SiNCs is little changed upon alkylation of the hydrogen-terminated particle surface, but the positions of the band edges are shifted significantly towards the vacuum level and the properties of the excited states are affected. 20 Experimental studies of the PL mechanism o...

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supporting

confidence: 82%

mentioning

confidence: 53%

Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

Chao

Houlton

Horrocks

et al. 2006

Applied Physics Letters

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“…Individual spectra are offset on the y-axis for clarity. [49][50][51]. These studies are consistent with an interpretation that the blue emission is associated with Si oxides and that the orange PL is particle sizedependent and derives from the quantum-confinement effect in Si.…”

Section: Origin Of the Orange And Blue Pl Emissionsupporting

confidence: 87%

“…The second possibility is much more likely because the previous Fourier transform infrared (FTIR) [6] and photoemission spectroscopy [12] data show that there is a small amount of oxide present in the samples. The work of others [48,50] also supports this interpretation. When nanocrystalline Si is oxidized, the Si-Si or Si-O-Si bonds are likely to weaken or break in many places because of the stress at the Si/SiO 2 interface [8].…”

Section: Origin Of the Orange And Blue Pl Emissionsupporting

confidence: 53%

Optical Properties of Nanostructured Silicon

Chao

2011

Comprehensive Nanoscience and Technology

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“…YongTaeg, Fujino, and Morinaga 103) recently reported that highly transparent hydroxylfree silica glass can be prepared by sintering a green compact prepared by micrometersized silica powders in a high vacuum environ ment. ElShall et al 104) produced silica nanoparticles by laser vaporization of polycrystalline silicon in a He/O 2 or Ar/O 2 at mosphere in a diffusion cloud chamber. Using this technique, a weblike agglomeration of silica nanoparticles was obtained.…”

Section: Pl From Silica Fine Particlesmentioning

confidence: 99%

Structure and Properties of Amorphous Silica and Its Related Materials: Recent Developments and Future Directions

Uchino

2005

J. Ceram. Soc. Japan

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Amorphous silica and related silicabased materials have been widely developed in optoelectronics and optical telecommunications technology. Despite comprehensive research for over the decades, the subject of amorphous silica continues to excite the interest of researchers in the field of chemistry, physics, and geology. This paper reviews some of the recent experimental and theoretical developments in the field, including mediumrange ord er, structural changes under pressures, vibrational and thermodynamic anomalies, and photoluminescence properties.

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Synthesis and Photoluminescence of Weblike Agglomeration of Silica Nanoparticles

Cited by 61 publications

References 3 publications

Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

Optical Properties of Nanostructured Silicon

Structure and Properties of Amorphous Silica and Its Related Materials: Recent Developments and Future Directions

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