Second-harmonic and linear optical spectroscopic study of silicon nanocrystals embedded in SiO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>

Wei, Junwei; Wirth, Adrian; Downer, M. C.; Mendoza, Bernardo S.

doi:10.1103/physrevb.84.165316

Cited by 14 publications

(16 citation statements)

References 61 publications

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“…In the present work we have evidenced that the PLE spectrum can be accounted for by two overlapping gaussian bands peaked around 3.4 eV and 5.1 eV. As suggested by Wei et al () the gaussian lineshapes indicate that the wide broadening (FWHM

>

1 eV) is governed by the inhomogeneity. On the one hand, these features are not directly attributable to specific defects at the Si/SiO

_{2}

interface, such as the NBOHC and the silanone which exhibit different excitation properties ().…”

Section: Discussionsupporting

confidence: 77%

“…The results that emerge from the excitation energy dependence and the comparison with literature data allow us to address the origin of this luminescence. Previous studies have indeed dealt with the excitation properties of Si‐nc related PL ; the PLE profile has been interpreted as the overlap of different contributions associated with excitons and Si/SiO

_{2}

interfacial defect states. In the present work we have evidenced that the PLE spectrum can be accounted for by two overlapping gaussian bands peaked around 3.4 eV and 5.1 eV.…”

Section: Discussionmentioning

confidence: 99%

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Photoluminescence of Si nanocrystals embedded in : Excitation/emission mapping

Vaccaro

Spallino

Zatsepin

et al. 2014

Physica Status Solidi (b)

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Time‐resolved photoluminescence from Si nanocrystals produced by 1100∘C thermal annealing of SiOx/SiO2 multilayers were investigated by tunable laser excitation, achieving a detailed excitation/emission pattern in the visible and UV range. The emission lineshape is a gaussian curve inhomogenously broadened because of the size distribution of Si nanocrystals, the excitation spectrum consists of the overlap of two gaussian bands centered around 3.4 and 5.1 eV. The mapping of luminescence spectral components with the lifetime points out the energy cubic dependence of the spontaneous emission rate. These findings are interpreted on the basis of models proposed in literature that associate this luminescence with quantum confinement of excitons or interfacial Si/SiO2 defects.

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>

1 eV) is governed by the inhomogeneity. On the one hand, these features are not directly attributable to specific defects at the Si/SiO

_{2}

interface, such as the NBOHC and the silanone which exhibit different excitation properties ().…”

Section: Discussionsupporting

confidence: 77%

_{2}

interfacial defect states. In the present work we have evidenced that the PLE spectrum can be accounted for by two overlapping gaussian bands peaked around 3.4 eV and 5.1 eV.…”

Section: Discussionmentioning

confidence: 99%

Photoluminescence of Si nanocrystals embedded in : Excitation/emission mapping

Vaccaro

Spallino

Zatsepin

et al. 2014

Physica Status Solidi (b)

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“…Over the past two decades, optical second‐harmonic generation (SHG) has become a standard technique for characterizing planar surfaces and interfaces of centrosymmetric materials in general 1, and of Si in particular 2–5. Recently SHG spectroscopy has also proven effective in characterizing the sharply curved interfaces of Si nanocrystals (NCs) 6, 7, which have opened possibilities for silicon photonics because of their efficient light emission at room temperature 8–10. To interpret SHG spectra of both planar and nanostructured Si interfaces accurately, comparison of spectral features with linear spectra of the same samples is essential.…”

Section: Introductionmentioning

confidence: 99%

“…To interpret SHG spectra of both planar and nanostructured Si interfaces accurately, comparison of spectral features with linear spectra of the same samples is essential. Such comparison has revealed that E 1 and E 2 critical point (CP) resonances in the linear optical spectra of bulk c‐Si often appear in modified form in SHG spectra of both planar Si interfaces 4, 5 and Si NCs 6, 7. For example, the E 1 resonance in SHG spectra of planar Si interfaces is invariably observed 0.1–0.2 eV lower in energy than the E 1 energy (3.4 eV) of bulk c‐Si, a shift generally attributed to strain gradients in the selvedge region 4.…”

Section: Introductionmentioning

confidence: 99%

“…Such comparison has also revealed resonances in SHG spectra that have no bulk c‐Si counterpart. Examples include spectral structures intermediate in energy between E 1 and E 2 observed in SHG spectra of planar Si(001)/SiO 2 11, planar Si(111)/SiO 2 12, and Si NCs embedded in SiO 2 7, attributed, respectively, to interfacial Si atoms that lack T d symmetry 11, interfacial suboxide groups 12, and a transitional amorphous Si shell at the NC/SiO 2 nanointerface 7.…”

Section: Introductionmentioning

confidence: 99%

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Blue‐shift of E₂ critical point resonance in optical second‐harmonic spectrum of Si nanocrystals

Mendoza

Wei

Downer

2012

Physica Status Solidi (b)

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The E 2 critical point (CP) resonance in the second-harmonic spectrum of silica-embedded Si nanocrystals (NCs) of 3 and 5 nm average diameter is observed to be blue-shifted by 0.5 eV from its energy (4.4 eV) in the linear dielectric response e(v) of the same samples. In contrast, the E 1 CP resonance (3.4 eV) and a third resonance intermediate in energy (3.8 eV) between E 1 and E 2 occur at nearly the same energy in both linear and nonlinear spectra. We explain the anomalous E 2 blue-shift by calculating the second-harmonic response function D(v) of the NCs analytically from the measured e(v) using a dipolium model. The analysis shows that the E 2 blue-shift originates from the screening factors of the form [e(2v) þ 2] À1 andÀ1 that are unique to second-harmonic generation (SHG) from nanospheres. Strong interaction between E 2 and E 0 1 (5.3 eV in bulk c-Si) resonant contributions to this factor pulls the E 2 peak response toward the higher E 0 1 energy while negligibly influencing lower energy resonances.

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Bi‐Modal Nonlinear Optical Contrast from Si Nanoparticles for Cancer Theranostics

Kharin

Lysenko

Rogov

et al. 2019

Advanced Optical Materials

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Having negligible toxicity compared to quantum dots based on compound semiconductors [1,2] and being capable of providing efficient imaging and therapeutic functionalities based on its unique physicochemical characteristics, [3][4][5] nanosilicon occupies a particularly important niche related to biological applications. The imaging functionality of nanosilicon typically employs photoluminescence (PL) of quantum-confined excitonic states in silicon (Si) nanocrystals (NCs) with sizes smaller than the exciton Bohr's radius (≈5 nm for the bulk crystalline Si (c-Si)), which enables tracking the presence of Si nanoparticles (NPs) in cells or tissues. [6][7][8][9][10][11][12][13] On the other hand, Si NPs can serve as efficient sensitizers of local heating under external stimuli to initiate hyperthermia-based therapies. As an example, Presenting a safe alternative to conventional compound quantum dots and other functional nanostructures, nanosilicon can offer a series of breakthrough hyperthermia-based therapies under near-infrared, radiofrequency, ultrasound, etc., excitation, but the size range to sensitize these therapies is typically too large (>10 nm) to enable efficient imaging functionality based on photoluminescence properties of quantum-confined excitonic states. Here, it is shown that large Si nanoparticles (NPs) are capable of providing two-photon excited luminescence (TPEL) and second harmonic generation (SHG) responses, much exceeding that of smaller Si NPs, which promises their use as probes for bi-modal nonlinear optical bioimaging. It is finally demonstrated that the combination of TPEL and SHG channels makes possible efficient tracing of both separated Si NPs and their aggregations in different cell compartments, while the resolution of such an approach is enough to obtain 3D images. The obtained bi-modal contrast provides lacking imaging functionality for large Si NPs and promises the development of novel cancer theranostic modalities on their basis.

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Second-harmonic and linear optical spectroscopic study of silicon nanocrystals embedded in SiO2

Cited by 14 publications

References 61 publications

Photoluminescence of Si nanocrystals embedded in : Excitation/emission mapping

Photoluminescence of Si nanocrystals embedded in : Excitation/emission mapping

Blue‐shift of E₂ critical point resonance in optical second‐harmonic spectrum of Si nanocrystals

Bi‐Modal Nonlinear Optical Contrast from Si Nanoparticles for Cancer Theranostics

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Second-harmonic and linear optical spectroscopic study of silicon nanocrystals embedded in SiO2

Cited by 14 publications

References 61 publications

Photoluminescence of Si nanocrystals embedded in : Excitation/emission mapping

Photoluminescence of Si nanocrystals embedded in : Excitation/emission mapping

Blue‐shift of E2 critical point resonance in optical second‐harmonic spectrum of Si nanocrystals

Bi‐Modal Nonlinear Optical Contrast from Si Nanoparticles for Cancer Theranostics

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Blue‐shift of E₂ critical point resonance in optical second‐harmonic spectrum of Si nanocrystals