Molecular behavior in the vibronic and excitonic properties of hydrogenated silicon nanoparticles

Rao, Satish; Mantey, Kevin; Therrien, Joel; Smith, Audrey; Nayfeh, Munir H.

doi:10.1103/physrevb.76.155316

Cited by 35 publications

(25 citation statements)

References 28 publications

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“…Sonification process reduces particle sizes, and filtration procedure allows large particle elimination. 10 This process finally produces ultrasmall monodispersed Si nanoparticles. Figure 2d.) Raman spectroscopy is a very useful technique for the observation of the quantum size effects in nanometer-sized particles and the structural characterization of nanomaterials.…”

Section: Resultsmentioning

confidence: 99%

“…A single sharp peak centered at 485.6 cm −1 could be seen in the Figure. The shift to lower frequency of the corresponding Raman modes for the Si-NCs can be attributed to the phonon confinement effect resulting from the reduced nanosized range structure. 10 A transmission dip at 265 nm wavelength indicates strong absorption of untreated samples at this wavelength. The filtrated samples exhibit comparatively flat absorption at low To obtain broadband PL emission, the CNS was excited with 370 nm wavelength light.…”

Section: Resultsmentioning

confidence: 99%

“…8,9 Optical vibronic and excitonic properties of these ultrasmall nanoparticles have also been obtained both experimentally and theoretically. 10 Laser ablation synthesis of nanoparticles is another promising solution.…”

Section: Introductionmentioning

confidence: 99%

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Post-Treatment of Silicon Nanocrystals Produced by Ultra-Short Pulsed Laser Ablation in Liquid: Toward Blue Luminescent Nanocrystal Generation

2012

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Blue luminescent colloidal silicon nanocrystals (Si-NCs) were produced in a two-stage process. In the first step, synthesis of Si-NCs was achieved by femtosecond pulsed laser ablation of a silicon wafer, which was immersed in deionized water. The size and the structural and the chemical characteristics of colloidal Si-NCs were investigated by TEM and EDAX analyses, and it is found out that the Si-NCs are in spherical shape and the particle diameters are in the range of 5−100 nm. In the second step, ultrasonic waves and filtering chemical-free post-treatment of colloidal Si-NCs solution was performed to reduce the particle size. High-resolution TEM (HRTEM) studies on post-treated colloidal solution clearly show that small (1−5.5 nm in diameter) Si-NCs were successfully produced. Raman spectroscopy results clearly confirms the generation of Si nanoparticles in the crystalline nature, and the Raman scattering study of post-treated Si-NCs confirms the reduction of the particle size. The UV−vis absorption and photoluminescence (PL) spectroscopy studies elucidate the quantum confinement effect of Si-NCs on the optical properties. The colloidal Si-NCs and post-treated Si-NCs solutions present strong absorption edge shifts toward UV region. Broadband PL emission behavior is observed for the initial colloidal Si-NCs, and the PL spectrum of post-treated Si-NCs presents a blue-shifted broadband PL emission behavior due to the particle size reduction effect.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Post-Treatment of Silicon Nanocrystals Produced by Ultra-Short Pulsed Laser Ablation in Liquid: Toward Blue Luminescent Nanocrystal Generation

2012

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“…the chemical potential of hydrogen) [38][39][40] . Recent measurements indicated that such reconstructed nanoparticles might indeed form 41 .…”

Section: B Structural Models Of Si Nanoparticlesmentioning

confidence: 99%

Increasing impact ionization rates in Si nanoparticles through surface engineering: A density functional study

et al. 2013

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We propose design pathways to improve the efficiency of Multiple Exciton Generation (MEG) in nanoparticle-based solar cells by carrying out ab-initio calculations of impact ionization (II) rates in semiconducting nanoparticles (NPs). In NPs with unreconstructed surfaces, quantum confinement has two competing effects: it enhances the effective Coulomb interaction and thus the II rates, but it also blue-shifts the gap, which tends to reduce the II rates. The competition of these effects determines the utility of NP based solar cells. We report that surface reconstruction of NPs can tip the balance towards the enhancement of II by creating a substantial density of states at lower energies. Our results suggest that manipulating the surfaces of NPs, e.g. by engineering the ligands and embedding structures, may lead to an efficient multi-exciton generation within the solar spectrum.

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“…Other theoretical simulations showed that the mechanical strain exerted is extremely high, corresponding to a pressure of several Gpa [40]. Because atoms on the surface are under high strain, they can undergo large-amplitude molecular-like vibrations to relieve the strain [41]; and hence can also couple efficiently to thermal and mechanical stimuli. Second-order nonlinearity in silicon opens up other prospective applications in optics, including modulation, amplification, gain and laser action, and signal processing [42].…”

Section: Optical Nonlinearity In Nanosiliconmentioning

confidence: 99%

Optics in Nanotechnology

Nayfeh

2016

Optics in Our Time

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Molecular behavior in the vibronic and excitonic properties of hydrogenated silicon nanoparticles

Cited by 35 publications

References 28 publications

Post-Treatment of Silicon Nanocrystals Produced by Ultra-Short Pulsed Laser Ablation in Liquid: Toward Blue Luminescent Nanocrystal Generation

Post-Treatment of Silicon Nanocrystals Produced by Ultra-Short Pulsed Laser Ablation in Liquid: Toward Blue Luminescent Nanocrystal Generation

Increasing impact ionization rates in Si nanoparticles through surface engineering: A density functional study

Optics in Nanotechnology

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