Acoustic vibrations in free‐standing single‐, bi‐layer nanomembranes and patterned wires

Bandhu, R. S.; Sooryakumar, R.; Bussmann, K.

doi:10.1002/andp.201000098

Cited by 4 publications

(3 citation statements)

References 46 publications

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“…Nanowalls and nanolines are prepared directly on glass substrates, therefore the nanowalls are not in contact through any bottom layer. 26,27 a Lattice constant (a), height (h), width (w), aspect ratio (h/w) and width to lattice constant ratio (w/a). Figure 2e was acquired with HV polarization in backscattering geometry.…”

Section:  Results and Discussionmentioning

confidence: 99%

Directional elastic wave propagation in high-aspect-ratio photoresist gratings: liquid infiltration and aging

Alonso-Redondo

Gueddida

et al. 2017

Nanoscale

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Determination of the mechanical properties of nanostructured soft materials and their composites in a quantitative manner is of great importance to improve the fidelity in their fabrication and to enable the subsequent reliable utility. Here, we report on the characterization of the elastic and photoelastic parameters of a periodic array of nanowalls (grating) by the non-invasive Brillouin light scattering technique and finite element calculations. The resolved elastic vibrational modes in high and low aspect ratio nanowalls reveal quantitative and qualitative differences related to the two-beam interference lithography fabrication and subsequent aging under ambient conditions. The phononic properties, namely the dispersion relations, can be drastically altered by changing the surrounding material of the nanowalls. Here we demonstrate that liquid infiltration turns the phononic function from a single-direction phonon-guiding to an anisotropic propagation along the two orthogonal directions. The susceptibility of the phononic behavior to the infiltrating liquid can be of unusual benefits, such as sensing and alteration of the materials under confinement.

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Section:  Results and Discussionmentioning

confidence: 99%

Directional elastic wave propagation in high-aspect-ratio photoresist gratings: liquid infiltration and aging

Alonso-Redondo

Gueddida

et al. 2017

Nanoscale

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“…No measurements of the vibrational modes of freestanding nanowires have been previously reported. However, several studies involving Brillouin-light-scattering (BLS) measurements have focused on the closely related subject of vibrational modes of polymeric nanolines on substrates or nanoscale membranes [30][31][32][33]. In this report, we present measurements and numerical modeling of the vibrational modes of monocrystalline hexagonal GaN nanowires at frequencies up to 40 GHz.…”

Section: Introductionmentioning

confidence: 99%

Vibrational modes of GaN nanowires in the gigahertz range

et al. 2012

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Brillouin-light-scattering measurements and finite-element modeling of vibrational spectra in the range of 5-40 GHz are presented for an array of monocrystalline GaN nanowires with hexagonal cross sections. Analysis of the spectra is substantially complicated by the presence of a distribution of nanowire diameters. The measurements and calculations reveal a variety of modes with simple flexural, higher-order flexural, approximately 'plane-strain', approximately longitudinal and torsional displacement patterns that are similar to the corresponding modes of isotropic cylinders. The largest peaks in the spectra with acoustic angular wavenumbers in the range of 4 to ~15 μm(-1) were determined to arise from modes with relatively large transverse displacements, consistent with inelastic light scattering arising predominantly from surface ripple. These dominant modes have finite frequencies in the limit of zero wavenumber, corresponding to transverse standing waves. At higher wavenumbers, the spectra provide evidence for increased scattering through elasto-optic coupling, especially with respect to the emergence of a peak from a mode analogous to the longitudinal guided modes of thin films.

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“…At present, experimental and theoretical studies of the phonon dispersion of nanowires and sheets are primarily restricted to high-energy optical phonons and to acoustic phonons at momenta near the center of the Brillouin zone, with wavevectors smaller than 0.1 2π/a, where a is the Si lattice parameter [18][19][20]. At these wavevectors, the vibrational properties of nanomembranes have been widely probed by optical techniques, such as Raman and Brillouin scattering [14,[21][22][23]. Phonon dispersions in macroscopic samples and in macroscopic quantities of zero-dimensional nanostructures have been probed by inelastic x-ray or neutron scattering [24][25][26][27].…”

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confidence: 99%

Thermal Diffuse Scattering as a Probe of Large-Wave-Vector Phonons in Silicon Nanostructures

et al. 2013

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Large-wave-vector phonons have an important role in determining the thermal and electronic properties of nanoscale materials. The small volumes of such structures, however, have posed significant challenges to experimental studies of the phonon dispersion. We show that synchrotron x-ray thermal diffuse scattering can be adapted to probe phonons with wave vectors spanning the entire Brillouin zone of nanoscale silicon membranes. The thermal diffuse scattering signal from flat Si nanomembranes with thicknesses from 315 to 6 nm, and a sample volume as small as 5 μm(3), has the expected linear dependence on the membrane thickness and also exhibits excess intensity at large wave vectors, consistent with the scattering signature expected from low-lying large-wave-vector modes of the membranes.

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Acoustic vibrations in free‐standing single‐, bi‐layer nanomembranes and patterned wires

Cited by 4 publications

References 46 publications

Directional elastic wave propagation in high-aspect-ratio photoresist gratings: liquid infiltration and aging

Directional elastic wave propagation in high-aspect-ratio photoresist gratings: liquid infiltration and aging

Vibrational modes of GaN nanowires in the gigahertz range

Thermal Diffuse Scattering as a Probe of Large-Wave-Vector Phonons in Silicon Nanostructures

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