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Silicon Quantum Dots (silicon + quantum_dot)

Distribution by Scientific Domains
Polymers and Materials Science80%

Selected Abstracts

Plasma Nanoparticle Synthesis: Luminescent Colloidal Dispersion of Silicon Quantum Dots from Microwave Plasma Synthesis: Exploring the Photoluminescence Behavior Across the Visible Spectrum (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 5 2009
Mater.
The cover picture shows a view into the plasma zone of a microwave plasma reactor, which is used to synthesize macroscopic quantities of single crystalline silicon nanoparticles with a very high production rate. These nanoparticles exhibit bright luminescence across the visible spectrum. On page 696, the authors report that the emission of such silicon nanoparticles can be tuned by changing their size and surface chemistry. [source]

Luminescent Colloidal Dispersion of Silicon Quantum Dots from Microwave Plasma Synthesis: Exploring the Photoluminescence Behavior Across the Visible Spectrum

ADVANCED FUNCTIONAL MATERIALS, Issue 5 2009
Anoop Gupta
Abstract Aiming for a more practical route to highly stable visible photoluminescence (PL) from silicon, a novel approach to produce luminescent silicon nanoparticles (Si-NPs) is developed. Single crystalline Si-NPs are synthesized by pyrolysis of silane (SiH4) in a microwave plasma reactor at very high production rates (0.1,10,g,h,1). The emission wavelength of the Si-NPs is controlled by etching them in a mixture of hydrofluoric acid and nitric acid. Emission across the entire visible spectrum is obtained by varying the etching time. It is observed that the air oxidation of the etched Si-NPs profoundly affects their optical properties, and causes their emission to blue-shift and diminish in intensity with time. Modification of the silicon surface by UV-induced hydrosilylation also causes a shift in the spectrum. The nature of the shift (red/blue) is dependent on the emission wavelength of the etched Si-NPs. In addition, the amount of shift depends on the type of organic ligand on the silicon surface and the UV exposure time. The surface modification of Si-NPs with different alkenes results in highly stable PL and allows their dispersion in a variety of organic solvents. This method of producing macroscopic quantities of Si-NPs with very high PL stability opens new avenues to applications of silicon quantum dots in optoelectronic and biological fields, and paves the way towards their commercialization. [source]

Water-Soluble Silicon Quantum Dots with Wavelength-Tunable Photoluminescence

ADVANCED MATERIALS, Issue 6 2009
Zhenhui Kang
H-terminated Si quantum dots (Si QDs) with 3,nm diameter are converted to water-soluble uniform-sized Si QDs after controlled oxidation in an EtOH/H2O2 solution. These dots present Si/SiOxHy core/shell nanostructures, and can be finely tuned to emit light in seven different colors due to the quantum size effect in the Si cores, exhibiting excellent photocatalytic activity in the visible range. [source]

Luminescent Colloidal Dispersion of Silicon Quantum Dots from Microwave Plasma Synthesis: Exploring the Photoluminescence Behavior Across the Visible Spectrum

ADVANCED FUNCTIONAL MATERIALS, Issue 5 2009
Anoop Gupta
Abstract Aiming for a more practical route to highly stable visible photoluminescence (PL) from silicon, a novel approach to produce luminescent silicon nanoparticles (Si-NPs) is developed. Single crystalline Si-NPs are synthesized by pyrolysis of silane (SiH4) in a microwave plasma reactor at very high production rates (0.1,10,g,h,1). The emission wavelength of the Si-NPs is controlled by etching them in a mixture of hydrofluoric acid and nitric acid. Emission across the entire visible spectrum is obtained by varying the etching time. It is observed that the air oxidation of the etched Si-NPs profoundly affects their optical properties, and causes their emission to blue-shift and diminish in intensity with time. Modification of the silicon surface by UV-induced hydrosilylation also causes a shift in the spectrum. The nature of the shift (red/blue) is dependent on the emission wavelength of the etched Si-NPs. In addition, the amount of shift depends on the type of organic ligand on the silicon surface and the UV exposure time. The surface modification of Si-NPs with different alkenes results in highly stable PL and allows their dispersion in a variety of organic solvents. This method of producing macroscopic quantities of Si-NPs with very high PL stability opens new avenues to applications of silicon quantum dots in optoelectronic and biological fields, and paves the way towards their commercialization. [source]

Raman scattering of acoustical modes of silicon nanoparticles embedded in silica matrix,

JOURNAL OF RAMAN SPECTROSCOPY, Issue 1-3 2006
M. Ivanda
Abstract The Raman scattering from acoustical phonons of silicon quantum dots in glass matrix was investigated. Two peaks that correspond to symmetric and quadrupolar spheroidal vibrations were found. A model calculation for in- and off-resonance scattering conditions was used, which considered the homogeneous broadening due to interaction with matrix and the inhomogeneous broadening due to particle size distribution. A strong dependence of the light-to-vibration coupling coefficient on the particles size was needed for fitting the Raman data. This result suggests that resonance with electronic transitions of the silicon nanoparticles is important for excitation at 514.5 nm. The size distribution obtained from the Raman data is in agreement with the results of high-resolution transmission electron microscopy. Copyright © 2006 John Wiley & Sons, Ltd. [source]