Scaleable synthesis route for silicon nanocrystal assemblies

Limaye, S. Y.; Subramanian, Shanthi; Göller, Bernhard; Diener, J.; Ковалев, Д. И.

doi:10.1002/pssa.200674320

Cited by 44 publications

(27 citation statements)

References 24 publications

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“…[21] The raw Si material was p-type metallurgical grade polycrystalline Si with major impurities Al and Fe in concentrations %0.07% (Vesta Ceramics, grade E) in form of powder with an average particle diameter of 4 mm. The etching was performed in a rotating drum mixer made of PTFE and capable of mixing up to 200 g of Si powder with up to 4 l etching solution.…”

Section: Methodsmentioning

confidence: 99%

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Purification of Nano‐Porous Silicon for Biomedical Applications

et al. 2011

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Recently, various bio‐medical applications of nanoporous silicon (np‐Si) have been suggested. This work investigates the biocompatibility of np‐Si particles taking into account hazardous residua confined in the pores after preparation. The emphasis is on the potential application of such particles as oxygen photosensitizer for photodynamic therapy of cancer, which requires both negligible toxicity of np‐Si particles in darkness and a high photo‐cyto‐toxic effect due to generation of singlet oxygen under illumination. Considerable amounts of water soluble toxic impurities are found to be present in the nanoporous shell of micrometer‐sized np‐Si particles immediately after their preparation by chemical etching of bulk silicon powder. The effects of several ordinary cleaning treatments are investigated by using thermal effusion mass‐spectroscopy and FTIR spectroscopy. A particular purification procedure is developed, capable to reduce the concentration of residual impurities to levels acceptable for bio‐medical applications while preserving the required photo‐activity of the np‐Si particles.

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Section: Methodsmentioning

confidence: 99%

“…Each particle has a %200 nm thick shell of nano-porous silicon, containing nano-crystals of 3-5 nm size. [21] The particles obtained in this way are referred here to as as-prepared np-Si particles. More details about their preparation, structure, and properties can be found in ref.…”

Section: Methodsmentioning

confidence: 99%

Purification of Nano‐Porous Silicon for Biomedical Applications

et al. 2011

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“…Production of the porSi powder is described in detail in another work. [5] In short, the initial polycrystalline Si powder is stain-etched in a HF-H 2 O-HNO 3 mixture producing a highly porous material similar to the electrochemically prepared porous Si. The internal surface area of the as-prepared H-terminated Si porous powder was about 250 m 2 g -1 as measured by N 2 adsorption by the standard Brunauer-Emmett-Teller method.…”

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confidence: 99%

“…The internal surface area of the as-prepared H-terminated Si porous powder was about 250 m 2 g -1 as measured by N 2 adsorption by the standard Brunauer-Emmett-Teller method. [5] The mean pore size, as directly estimated from scanning electron microscopy (SEM) measurements ( Fig. 1), was ca.…”

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confidence: 99%

Surfactant‐Modified Hydrophilic Nanostructured Porous Silicon for the Photosensitized Formation of Singlet Oxygen in Water

et al. 2007

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Porous silicon (porSi), which contains luminescent Si nanocrystal assemblies, is a promising semiconductor material for the photosensitized formation of singlet oxygen, 1 O 2 , for biological applications. However, because as-prepared luminescent Si nanocrystals are H-terminated and therefore hydrophobic, the first step to create a prototype of Si nanocrystalbased photosensitizer should be a modification of the Si nanocrystal surface with the aim to make it hydrophilic and able to work in a biological ambient. Such surface modification by surfactants should not, however, result in a decrease of the nanocrystals' durability that may, in principle, take place because of surfactant-induced weakening of surface tension and the consequent increase of interaction with H 2 O molecules. Surfactants should not also decrease the ability of the nanocrystals to transfer the excitation energy to acceptors (first of all molecular oxygen) on their surface. These rather contradictory tasks have been largely solved in the present work by use of nonionic surfactants physically adsorbed on the porSi surface.One of the strategic objectives of nanotechnology is the development of new materials of nanometer size that have entirely new physical properties, and, therefore, new functionality. Over the last decade, tailoring of material characteristics by size control has been demonstrated for many types of semiconductors. Optical and electronic properties of semiconductor nanocrystals can be simply engineered by changing their size and composition. When electrons and holes are squeezed into a dimension that approaches a critical size, quantum-confinement effects become apparent. This effect can be seen experimentally as a widening of the semiconductor nanocrystal bandgap.[1]

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“…22 Metallurgical-grade polycrystalline Si powder (Vesta Ceramics, with mean diameter 3-11 μm) was immersed in an aqueous HF solution, to which HNO 3 was gradually added in the ratio HF : HNO 3 : H 2 O = 6 : 1 : 30 for 20 min at 30 • C. After the etching, the powder was filtered out from the etching solution and dried in room air for 24 h. With this procedure, the porous layer was formed on the surface of the Si powder owing to the oxidation of the Si surface and simultaneous dissolution of the oxidized Si. The as-prepared PSi powder showed an efficient luminescence by an UV light excitation.…”

Section: Methodsmentioning

confidence: 99%

Properties of magnetic nickel/porous-silicon composite powders

Nakamura

Adachi

2012

AIP Advances

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The magnetic and photoluminescence (PL) properties of nickel/porous-silicon (Ni/PSi) composite powders are investigated. Ni/PSi composite powders are prepared by stain etching of Si powder in a HF/HNO3 solution followed by electroless plating of Ni nanoparticles on the stain-etched PSi powder in a NiCl2 solution. The Ni/PSi powders exhibit hydrophillicity, superparamagnetism caused by the deposited Ni nanoparticles, and orange-red PL owing to the nanostructured PSi surface. The degree of magnetization decreases with increasing Ni plating time, indicating its dependence on the size of the Ni nanoparticles. The Ni/PSi composite powders also show a stronger magnetization as compared to that of the Ni-particle-plated Si powder. The stronger magnetization results from the larger surface area of PSi. The PL intensity, peak wavelength, and lifetime of Ni/PSi are strongly dependent on the NiCl2 concentration. This dependence is due to the different thickness of the oxide overlayer on the PSi surface formed during the Ni plating process. The existence of the oxide overlayer also results in a small change in the PL intensity against excitation time

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Scaleable synthesis route for silicon nanocrystal assemblies

Cited by 44 publications

References 24 publications

Purification of Nano‐Porous Silicon for Biomedical Applications

Purification of Nano‐Porous Silicon for Biomedical Applications

Surfactant‐Modified Hydrophilic Nanostructured Porous Silicon for the Photosensitized Formation of Singlet Oxygen in Water

Properties of magnetic nickel/porous-silicon composite powders

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