Colloidal suspensions of silicon nanocrystals: from single nanocrystals to photonic structures

Valenta, J.; Janda, P.; Dohnalová, Kateřina; Nižňanský, Daniel; Vacha, František; Linnros, Jan

doi:10.1016/j.optmat.2004.08.060

Cited by 41 publications

(26 citation statements)

References 10 publications

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“…The intense PL band centered at 400 nm is mainly associated with the blue Si-NCs, since the isopropanol luminescence is known to be too low. These PL emission bands have been reported before [8,24,25]. Figure 7b shows the PL spectra of the coated red and blue Si-NC films before thermal annealing.…”

Section: Photoluminescence Propertiessupporting

confidence: 77%

“…One of the proposed approaches is to use dielectric matrices with silicon nanocrystals (Si-NCs) or nano-agglomerates as active media. Among several other techniques, chemical methods have been used to fabricate such materials [2][3][4][5][6][7][8][9][10]. The origin of the photoluminescence (PL) of Si-NCs embedded into oxide films is still controversial [11], but there are two principal models commonly used to explain the emission mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…The origin of the photoluminescence (PL) of Si-NCs embedded into oxide films is still controversial [11], but there are two principal models commonly used to explain the emission mechanism. One is known as the Quantum Confinement Effect (QCE), in which the radiative process is carried out by electron-hole recombination in the Si-NCs; silicon nanocrystals below 5 nm show an effect of a quasi-direct bandgap due to the boundary conditions [6,8,12,13]. The second model proposes the formation of defect-states at the Si-NCs/SiO 2 interface where radiative recombination occurs [10,14,15].…”

Section: Introductionmentioning

confidence: 99%

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Luminescent Properties of Silicon Nanocrystals:Spin on Glass Hybrid Materials

et al. 2017

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Abstract:The photoluminescence characteristics of films consisting of Si nanocrystals either coated with or embedded into Spin on Glass (SOG) were studied. Si nanocrystals showing red or blue luminescence when suspended in alcohol solution were obtained from porous silicon films. These were then either deposited in Si substrates and coated with SOG, or mixed in an SOG solution that was later spun on Si substrates. Both types of films were thermally annealed at 1100 • C for three hours in N 2 atmosphere. Transmission electron microscopy measurements showed a mean diameter of 2.5 nm for the Si nanocrystals, as well as the presence of polycrystalline Si nanoagglomerates. These results were confirmed by X-ray diffraction studies, which revealed the (111), (220) and (311) Bragg peaks in Si nanocrystals. Fourier transform infrared spectroscopy studies showed that the coated films present higher chemical reactivity, promoting the formation of non-stoichiometric SiO 2 , while the embedded films behave as a stoichiometric SiO 2 after the thermal annealing. The PL (photoluminescence) characterization showed that both embedded and coated films present emission dominated by the Quantum Confinement Effect before undergoing any thermal treatment. After annealing, the spectra were found to be modified only in the case of the coated films, due to the formation of defects in the nanocrystals/SiO 2 interface.

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Section: Photoluminescence Propertiessupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Luminescent Properties of Silicon Nanocrystals:Spin on Glass Hybrid Materials

et al. 2017

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“…Colloidal suspensions studied in this work were prepared by pouring ethanol or isopropanol onto the PSi powder and mixing in an ultrasonic bath. Optical microscopical observation shows that the original powder contains many large PSi grains of several mm or even tens of mm and sonication is inefficient to break the largest grains to sizes below a mm [30]. Further size selection is necessary.…”

Section: Methodsmentioning

confidence: 99%

Light‐Emission Performance of Silicon Nanocrystals Deduced from Single Quantum Dot Spectroscopy

Valenta

Fučíková

Vacha

et al. 2008

Adv Funct Materials

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Spectra of individual silicon nanocrystals within porous Si grains are studied by the wide‐field imaging microspectroscopy and their ON–OFF blinking is detected by the confocal single‐photon‐counting microscopy. Observed spectral and blinking properties comprise all features reported before in differently prepared single Si nanocrystals (SiNCs). Former apparently contradictory results are shown to be due to different experimental conditions. When the effect of dark periods (OFF switching) is removed the common ultimate photoluminescence properties of SiO2 passivated SiNCs are found, namely the quantum efficiency (QE) of about 10–20% up to the pumping rate corresponding to one exciton average excitation per quantum dot. At higher pump rates the QE is slowly decreasing as the 0.7th power of excitation. This is most likely due to Auger recombination which, however, seems to be weakened compared with measurements of nanocrystal assemblies. We conclude that SiNCs may be pumped above one exciton occupancy to yield a higher light emission, being advantageous for applications.

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“…Cichos et al [14] and, more recently, Valenta et al [15] also prepared colloidal suspensions of Si NCs from light-emitting porous Si grains. Valenta et al obtained nanoparticles by mechanical pulverization of electrochemically etched layers.…”

Section: Electrochemical Etching and Ultrasonicationmentioning

confidence: 99%

Optical Properties of Nanostructured Silicon

Chao

2011

Comprehensive Nanoscience and Technology

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Colloidal suspensions of silicon nanocrystals: from single nanocrystals to photonic structures

Cited by 41 publications

References 10 publications

Luminescent Properties of Silicon Nanocrystals:Spin on Glass Hybrid Materials

Luminescent Properties of Silicon Nanocrystals:Spin on Glass Hybrid Materials

Light‐Emission Performance of Silicon Nanocrystals Deduced from Single Quantum Dot Spectroscopy

Optical Properties of Nanostructured Silicon

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