Highly spherical SiC nanoparticles grown in nonthermal plasma

Galář, Pavel; Stuchlı́k, J.; Müller, Martin; Kočka, J.; Kůsová, Kateřina

doi:10.1002/ppap.202100127

Cited by 6 publications

(3 citation statements)

References 44 publications

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“…Commensurate with our recent work on the plasma synthesis of Si NCs from the liquid precursor cyclohexasilane (CHS), 39,40 and with an array of experience related to Si NC photophysics in general, 41−46 we draw here on recent atmospheric-pressure plasma SiC NC synthesis schemes, 17,33 noting that there is a paucity of related work in nonthermal plasmas. 47,48 The growth mechanism that we recently postulated for Si NCs from vapor-phase liquid precursors in low-pressure plasmas is a type of step-growth "polymerization", 40 and we anticipate that a similar pathway applies to SiC NCs. In this contribution, SiC NCs of controlled 2−4 nm size are produced through a nonthermal plasma synthesis scheme using tetramethylsilane (TMS) as a precursor, where reactor pressure, or, equivalently, plasma residence time is demonstrated to be the primary variable for tuning the NC size.…”

Section: ■ Introductionmentioning

confidence: 84%

Silicon-Carbide Nanocrystals from Nonthermal Plasma: Surface Chemistry and Quantum Confinement

et al. 2022

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Silicon-carbide (SiC) nanocrystals (NCs) of controlled 2–4 nm size are produced in low-pressure nonthermal plasma from the simple alkylsilane precursor tetramethylsilane (TMS). Generating material on the slightly carbon-rich side of 50/50 Si/C, we establish a process for thermally removing residual carbon, which in turn promotes a degree of intrinsic solubility in polar solvents such as isopropanol (IPA). Using the size-dependent Tauc gap of luminescent silicon NCs (Si NCs) as a point of reference, we demonstrate quantum confinement in nanocrystalline β-SiC but without measurable luminescence. Surface-sensitive spectroscopic techniques reveal an oxide shell surrounding a nanocrystalline SiC core, where negative surface charge groups promote solubility while likely acting as efficient trap states for nonradiative recombination. An analytical model is presented that combines electrostatic repulsion with van der Waals attraction to explain experimental observations of concentration-dependent cluster formation and reversible NC aggregation. We anticipate that these materials will be of interest for use as nanofillers in polymer composites and in specialty coatings, while providing a foundation for exploring routes to band gap emission from nanocrystalline SiC.

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Section: ■ Introductionmentioning

confidence: 84%

Silicon-Carbide Nanocrystals from Nonthermal Plasma: Surface Chemistry and Quantum Confinement

et al. 2022

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“…SiQDs were synthesized in a noncommercial flow-through glass reactor with low-pressure nonthermal plasma as detailed elsewhere. 40 The output source power was set to 150 W. The PL wavelength of the sample was tuned by changing the composition of the synthesis gas ((i) 80 sccm of silane in Ar with 10 sccm of H 2 , (ii) 80 sccm of silane in Ar with 50 sccm of H 2 , and (iii) 40 sccm of silane, 40 sccm of Ar, and 100 sccm of hydrogen). The estimated residence time of the forming nanoparticles in the plasma was about 15 ms.…”

Section: Sample Fabrication 211 Nonthermal Plasma Synthesis (Ntp-siqds)mentioning

confidence: 99%

Universal Radiative Lifetimes in the Long-Lived Luminescence of Si Quantum Dots

Popelář,

Galář,

Matějka

et al. 2023

J. Phys. Chem. C

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Silicon quantum dots (SiQDs) represent a perspective light emitting material. Here, we show that their typical long-lived photoluminescence can be fully radiative. However, despite the fully radiative nature, the overall yield of light emission from SiQDs is still hindered by dark QDs, the understanding of which is only very limited so far. To address this problem, first, we experimentally quantify the dependence of radiative lifetimes on the emission photon energy and show that this dependence is universal across different types of samples and different laboratories. Second, we use this dependence to quantify the internal photoluminescence quantum yield using simply the emission-photon energy dependence of measured photoluminescence (PL) lifetimes as the input. The knowledge of the internal quantum yield then lets us determine the relative population of dark SiQDs if the external quantum yield is known. The application of our approach to the decoupling of the influence of nonradiative processes and dark quantum dots can be easily applied by other researchers, which will shed more light on the mechanism of PL quenching in dark QDs. Besides focusing on dark QDs, we observe that the PL decays of SiQDs can be non-single-exponential despite being fully radiative and suggest the natural variation of radiative lifetimes as a possible mechanism responsible for the non-single-exponential character of PL decay. Lastly, we emphasize the importance of average lifetimes as the quantity characterizing PL decays, especially in the case of non-single-exponential PL decays in the absence of a generally accepted physical model explaining the PL dynamics.

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“…SiC nanostructures can be synthesized with various methods. For instance, a synthesis of highly spherical cubic (3C) SiC nanocrystals (50–150 nm) using nonthermal plasma has been recently reported where the Si seed remained present in the middle of the SiC nanocrystals [ 3 ]. The vapor-liquid-solid (VLS) is also known technique to grow SiC [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

Amino-Termination of Silicon Carbide Nanoparticles

Czene,

Jegenyes,

Krafcsik

et al. 2023

Nanomaterials

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Silicon carbide nanoparticles (SiC NPs) are promising inorganic molecular-sized fluorescent biomarkers. It is imperative to develop methods to functionalize SiC NPs for certain biological applications. One possible route is to form amino groups on the surface, which can be readily used to attach target biomolecules. Here, we report direct amino-termination of aqueous SiC NPs. We demonstrate the applicability of the amino-terminated SiC NPs by attaching bovine serum albumin as a model for functionalization. We monitor the optical properties of the SiC NPs in this process and find that the fluorescence intensity is very sensitive to surface termination. Our finding may have implications for a few nanometers sized SiC NPs containing paramagnetic color centers with optically read electron spins.

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Highly spherical SiC nanoparticles grown in nonthermal plasma

Cited by 6 publications

References 44 publications

Silicon-Carbide Nanocrystals from Nonthermal Plasma: Surface Chemistry and Quantum Confinement

Silicon-Carbide Nanocrystals from Nonthermal Plasma: Surface Chemistry and Quantum Confinement

Universal Radiative Lifetimes in the Long-Lived Luminescence of Si Quantum Dots

Amino-Termination of Silicon Carbide Nanoparticles

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