Antenna resonances in low aspect ratio semiconductor nanowires

Traviss, Daniel; Schmidt, Mikołaj K.; Aizpurua, Javier; Muskens, Otto L.

doi:10.1364/oe.23.022771

Cited by 33 publications

(42 citation statements)

References 65 publications

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“…We choose SiNWs with length long compared to the focal spot of the illuminating optics (all data acquired on NWs with L = 7 µm) in order to obtain a purely Mie-like response. 54 SEM images of selected rectangular SiNWs are shown in figure 2e. The images are obtained from a second sample, fabricated with the exact same process parameters but on a non-insulating silicon-on-insulator (SOI) substrate.…”

Section: Asymmetric Rectangular Silicon Nanowiresmentioning

confidence: 99%

Strongly Directional Scattering from Dielectric Nanowires

et al. 2017

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It has been experimentally demonstrated only recently that a simultaneous excitation of interfering electric and magnetic resonances can lead to uni-directional scattering of visible light in zerodimensional dielectric nanoparticles. We show both theoretically and experimentally, that strongly anisotropic scattering also occurs in individual dielectric nanowires. The effect occurs even under either pure transverse electric or pure transverse magnetic polarized normal illumination. This allows for instance to toggle the scattering direction by a simple rotation of the incident polarization. Finally, we demonstrate that directional scattering is not limited to cylindrical cross-sections, but can be further tailored by varying the shape of the nanowires.The search for ways to control light at subwavelength dimensions has increasingly attracted the interest of researchers for about the last two decades. Due to their strong polarizability and tunable plasmon resonances, metallic nanostructures are particularly suitable for the nanoscale manipulation of light -especially at visible frequencies. 1 However, such plasmonic structures suffer from certain drawbacks like strong dissipation associated to the large imaginary part of the dielectric function in metals.Recently, dielectric nanostructures from high-index materials have proven to offer a promising alternative platform with far lower losses. 2 Like in plasmonics, it is possible to tune optical resonances from the near ultraviolet to the near infrared, yet with almost no dissipative losses. At these resonances, which can be of both electric or magnetic nature, strong local field enhancements 3 and intense scattering 4 occur, tunable via the material and the geometry of the nanostructure. Prominent dielectric materials are, among others, silicon, germanium or III-V compound semiconductors with indirect band-gap. 5,6 Conventional geometries include spherical nanoparticles 4 or nanowires (NWs), 7,8 but also more complex dielectric nanostructures 9 . Dielectric optical antennas are promising candidates for applications in fieldenhanced spectroscopy, 10-13 imaging, 14 to enhance and control nonlinear effects [15][16][17] or to increase the efficiency in photovoltaics 18 .A peculiarity of dielectric particles is the possibility to simultaneously obtain a strong electric and magnetic response using very simple geometries. 3,4,19,20 Recently, it has been independently shown by two research groups, 21,22 that exclusive forward (FW) or backward (BW) scattering, predicted by Kerker et al. in 1983 for hypothetical magneto-dielectric particles, 23 can be real- * ized in the visible spectral range using dielectric nanoparticles. Kerker et al. described two possible configurations, called the Kerker conditions. At the first Kerker condition zero backward scattering occurs for equal electric permittivity and magnetic permeability ( r = µ r ). The second Kerker condition predicts zero forward scattering in small spherical particles when the first order magnetic and electric Mie coeff...

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Section: Asymmetric Rectangular Silicon Nanowiresmentioning

confidence: 99%

Strongly Directional Scattering from Dielectric Nanowires

et al. 2017

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“…The slight radial asymmetry of the near-field intensity is observed due to substrate effect. The magnetic field for the fundamental TE mode (TE 01 ) is highly confined within the NW core, indicating strong light trapping in a whispering-gallery mode configuration 20 . The high field intensities inside the structure can directly contribute to enhanced absorption.…”

Section: Resultsmentioning

confidence: 99%

“…3. Due to the combination effect of 1D longitudinal and radial transverse components, the resonance of TM modes shifts to higher energy with respect to TE modes, and thus degeneracies of TE and TM modes are broken 20 . The dramatic drop of the absorption efficiency at 550 nm is due to the low absorption coefficient below the bandgap of ZnTe.…”

Section: Resultsmentioning

confidence: 99%

“…For the NW with a finite length, the electromagnetic field of the incident light suffers diffraction at the two ends of NW and introduces a longitudinal wavevector along the NW. If the NW length satisfies certain conditions, longitudinal-field Fabry-Perot (F-P) resonance will be generated and leads to hybrid modes through interaction with transverse radial resonances 20 .…”

Section: Structure Design and Fabricationmentioning

confidence: 99%

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Extreme absorption enhancement in ZnTe:O/ZnO intermediate band core-shell nanowires by interplay of dielectric resonance and plasmonic bowtie nanoantennas

Nie

Chen

et al. 2017

Sci Rep

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Intermediate band solar cells (IBSCs) are conceptual and promising for next generation high efficiency photovoltaic devices, whereas, IB impact on the cell performance is still marginal due to the weak absorption of IB states. Here a rational design of a hybrid structure composed of ZnTe:O/ZnO core-shell nanowires (NWs) with Al bowtie nanoantennas is demonstrated to exhibit strong ability in tuning and enhancing broadband light response. The optimized nanowire dimensions enable absorption enhancement by engineering leaky-mode dielectric resonances. It maximizes the overlap of the absorption spectrum and the optical transitions in ZnTe:O intermediate-band (IB) photovoltaic materials, as verified by the enhanced photoresponse especially for IB states in an individual nanowire device. Furthermore, by integrating Al bowtie antennas, the enhanced exciton-plasmon coupling enables the notable improvement in the absorption of ZnTe:O/ZnO core-shell single NW, which was demonstrated by the profound enhancement of photoluminescence and resonant Raman scattering. The marriage of dielectric and metallic resonance effects in subwavelength-scale nanowires opens up new avenues for overcoming the poor absorption of sub-gap photons by IB states in ZnTe:O to achieve high-efficiency IBSCs.

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“…The rectangular section is varied by changing the SiNWs width. The length L = 7 µm is chosen large compared to the focal spot of the illuminating optics in order to obtain a purely Mie-like response [116]. All NWs have excellent surface properties, low roughness and steep flanks, verified by scanning electron microscopy.…”

Section: Rectangular Nanowiresmentioning

confidence: 99%

Fano-resonances in High Index Dielectric Nanowires for Directional Scattering

Wiecha

Cuche

Kallel

et al. 2018

Springer Series in Optical Sciences

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High refractive index dielectric nanostructures provide original optical properties thanks to the occurrence of size-and shape-dependent optical resonance modes. These modes commonly present a spectral overlap of broad, low-order modes (e.g. dipolar modes) and much narrower, higher-order modes. The latter are usually characterized by a rapidly varying frequency-dependent phase, which -in superposition with the lower order mode of approximately constant phase -leads to typical spectral features known as Fano resonances. Interestingly, such Fano resonances occur in dielectric nanostructures of the simplest shapes. In spheroidal nanoparticles, interference between broad magnetic dipole and narrower electric dipole modes can be observed. In high aspect-ratio structures like nanowires, either the electric or the magnetic dipolar mode (depending on the illumination conditions) interferes with higher order multipole contributions of the same nature (electric or magnetic). Using the analytical Mie theory, we analyze the occurrence of Fano resonances in high-index dielectric nanowires and discuss their consequences like unidirectional scattering. By means of numerical simulations, we furthermore study the impact on those Fano resonances of the shape of the nanowire cross-sections as well as the coupling of two parallel nanowires. The presented results show that all-dielectric nanostructures, even of simple shapes, provide a reliable low-loss alternative to plasmonic nanoantennas. arXiv:1801.05601v1 [physics.app-ph]

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Antenna resonances in low aspect ratio semiconductor nanowires

Cited by 33 publications

References 65 publications

Strongly Directional Scattering from Dielectric Nanowires

Strongly Directional Scattering from Dielectric Nanowires

Extreme absorption enhancement in ZnTe:O/ZnO intermediate band core-shell nanowires by interplay of dielectric resonance and plasmonic bowtie nanoantennas

Fano-resonances in High Index Dielectric Nanowires for Directional Scattering

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