Plasmon Resonant Cavities in Vertical Nanowire Arrays

Bora, Mihail; Fasenfest, B; Behymer, Elaine; Chang, Ansi; Nguyễn, Hoàng Tùng; Britten, Jerald A.; Larson, Cindy; Chan, James W.; Miles, Robin R.; Bond, Tiziana C.

doi:10.1021/nl1008376

Cited by 71 publications

(49 citation statements)

References 24 publications

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“…Various NP arrays using e-beam lithography 32 , anodized aluminum oxide templates 33,35 , nanoimprinting 34 , oxygen-plasma-stripping-of-photoresist technique 36 , ion milling 37 , interference lithography 38,40 , and coating of multi-walled carbon nanotubes 39 have been reported. Recently, we have developed a new method to fabricate wafer scale Ag-capped Si nanopillar (Ag NP) SERS substrates utilizing maskless lithography.…”

Section: Introductionmentioning

confidence: 99%

Wafer-Scale Leaning Silver Nanopillars for Molecular Detection at Ultra-Low Concentrations

Rindzevicius

Schmidt

et al. 2015

J. Phys. Chem. C

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Wafer-scale surface-enhanced Raman scattering (SERS) substrates fabricated using maskless lithography are important for scalable production targets. Large-area, leaning silver-capped silicon nanopillar (Ag NP) structures suitable for SERS molecular detection at extremely low analyte concentrations are investigated. Theoretical results show that isolated Ag NPs essentially support two localized surface plasmon (LSP) modes. The most prominent LSP resonance is observed in the near-infrared region (~800 nm) and can be tuned by changing the diameter of the silicon nanopillars (Si NPs). The corresponding electric field distribution maps indicate that the maximum E-field enhancement is found at the Ag cavity, i.e. the bottom part of the Ag cap. We argue that the plasmon coupling between the resonant Ag cap cavities contributes most to the enhancement of the Raman signal. We experimentally evaluate these findings and show that by exposing Si NPs to an O 2 -plasma the average Ag NP cluster size, and thus the overall inter-pillar coupling, can be systematically reduced. We show that deposition of Cr adhesion layers on Si NPs (>3 nm) introduce plasmon coupling loss to the Ag NP LSP cavity mode that significantly reduces the SERS intensity. Results also show that short exposures to the O 2 -plasma and the use of 1-3 nm Cr adhesion layers are advantageous for reducing the signal background noise from Ag NPs. In addition, influence of the Ag NP height and Ag metal thickness on SERS intensities is investigated and optimal fabrication process parameters are evaluated. Finally, the SERS spectrum from 100 pM of trans-1,2-bis (4-pyridyl) ethylene (BPE) is recorded showing distinct characteristic Raman vibrational modes. The calculated enhancement factor is of the order of 10 8 , and the SERS signal intensity exhibits a standard deviation of around 14% (660 data points) across a 5x5 mm 2 surface area.

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Section: Introductionmentioning

confidence: 99%

Wafer-Scale Leaning Silver Nanopillars for Molecular Detection at Ultra-Low Concentrations

Rindzevicius

Schmidt

et al. 2015

J. Phys. Chem. C

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“…Besides future applications as force sensors, such ultraflexible nanowire arrays are ideal model systems to explore the nonlinear dynamics and coupling phenomena in nanomechanical arrays [39,40], for which synchronization [41] and Q-boosting [42] have been predicted. Metallized nanowire heads will allow to integrate plasmonic functionality [43] or a transport degree of freedom [44]. Finally, the integration of photonic elements such as Bragg reflectors or quantum dots can be envisioned [45,46], which may lead to additional functionality incorporating optomechanical arrays [47,48].…”

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confidence: 99%

Size-independent Young's modulus of inverted conical GaAs nanowire resonators

Paulitschke

Seltner

Lebedev

et al. 2013

Applied Physics Letters

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We explore mechanical properties of top down fabricated, singly clamped inverted conical GaAs nanowires. Combining nanowire lengths of 2 − 9 µm with foot diameters of 36 − 935 nm yields fundamental flexural eigenmodes spanning two orders of magnitude from 200 kHz to 42 MHz. We extract a size-independent value of Young's modulus of (45 ± 3) GPa. With foot diameters down to a few tens of nanometers, the investigated nanowires are promising candidates for ultra-flexible and ultra-sensitive nanomechanical devices.PACS numbers: 46.70. Hg,62.20.de,62.23.Hj,62.25.Jk Keywords: Nanomechanical systems, mechanical resonators, nanowires, Young's modulusThe rise of nanotechnologies in basic research as well as the applied sciences goes along with the development of more and more compact and sensitive devices. For example, nanomechanical systems (NEMS) are promising candidates for ultra-responsive mass [1,2], force [3][4][5] or biosensors [6][7][8], as well as accelerometers [9] or oscillators [10]. The successful realization of such devices is enabled by a combination of three key factors: integrated architectures, reliable fabrication and high sensitivity. Particularly for integrated sensing devices the vertical arrangement of dense arrays of micro-or nanowires [5] is considered beneficial. A compact sensor design with higher functionality and reproducible control over device parameters is facilitated by top down fabrication. Finally, the device's sensitivity is closely related to its spring constant, which is a function of both geometry and material properties such as Young's modulus E, as, quite generally, a softer spring allows resolving smaller signals. Thus, detailed knowledge of the mechanical properties is crucial to predict the performance of a device. Typically, Young's moduli are determined by relating the measured resonance frequency f 0 of the resonator's fundamental flexural mode to its geometrical dimensions [11][12][13][14][15][16]. A prominent example is the simple singly-clamped cylindrical beam for which Euler Bernoulli beam theory [17] yields the well-known relationfor aspect ratios r/h < 0.1 with mass density ρ, beam radius r and length h.Here we present a nanomechanical resonator which is an excellent candidate for a nanomechanical sensing device. Figure 1 shows nanowires etched into an (100)-oriented GaAs substrate, combining the benefits of top down fabrication with an ultrasoft mechanical response, allowing for immediate integration into a sensing array. * present address: Universität Konstanz, Universitätsstr. 10, 78457 Konstanz, Germany; eva.weig@uni.konstanz.de Notably, the nanowires are not cylindrical, but of inverted conical shape. This is apparent from the magnified nanowire in the right part of Fig. 1 featuring a length of h = 6 µm, a head radius of R = 264 nm and a foot radius of only r = 85 nm, which corresponds to a taper angle of ϕ ≈ 1.7 • . While the narrow nanowire foots enable high force sensitivities [18,19], the relatively large nanowire heads can easily be resolved in an optical...

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“…We notice that gold nanotubes demonstrate versatile performances for the plasmonic resonators. Beside the advantage of strong coupling at periodic metal-dielectric interfaces in the structures such as gold nanorods and nanowire arrays, [45][46][47] the gold nanotubes with a hollow geometry are similar to the subwavelength hole arrays which exhibit the effect of extraordinary optical transmission [48][49][50] leading to sharper Fabry-Pérot resonances originating from the reflections at the nanotube terminations. In this case, the metamaterials composed of an array of gold nanotubes becomes a promising candidate for plasmonic resonators since it allows to achieve both strong confinement of electric fields at the nanotube walls with low losses.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Plasmonic Cavity Modes in Arrays of Gold Nanotubes

Wang

Zhang

Song

et al. 2016

Advanced Optical Materials

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Plasmonic structures are known to confine light at the nanometer scale, and they exhibit enhanced electromagnetic fields localized in small mode volumes. Here we study plasmonic resonators based on a metamaterial consisting of periodic arrays of gold nanotubes embedded into anodic aluminum oxide and demonstrate strong confinement of local fields with low losses. We observe higher-order resonance modes of surface plasmons localized in gold nanotubes when the nanotube length exceeds some critical values. Our numerical simulations suggest that for the higher-order modes, the electric fields are mainly localized at the interfaces between aluminum oxide and gold in the form of the standing-wave longitudinal plasmonic modes, partially localized in the pores and at two ends of the nanotubes owing to the strong coupling of the Fabry-Pérot resonances with extraordinary optical transmission in the periodical structures through the inner nanochannels of the nanotubes, so that the nanotubes play a role of efficient cavity resonators. We reveal the existence of hybrid resonant cavity modes with asymmetrical distributions of the electric field resulting from the near-field coupling of both transverse and longitudinal modes in the gold nanotube metamaterials.3

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Plasmon Resonant Cavities in Vertical Nanowire Arrays

Cited by 71 publications

References 24 publications

Wafer-Scale Leaning Silver Nanopillars for Molecular Detection at Ultra-Low Concentrations

Wafer-Scale Leaning Silver Nanopillars for Molecular Detection at Ultra-Low Concentrations

Size-independent Young's modulus of inverted conical GaAs nanowire resonators

Hybrid Plasmonic Cavity Modes in Arrays of Gold Nanotubes

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