Silicon-Based SERS Substrates Fabricated by Electroless Etching

El‐Sayed, Mohamed Y.; Gouda, Abdelaziz; Ismail, Yehea; Swillam, Mohamed A.

doi:10.1109/jlt.2017.2707476

Cited by 24 publications

(10 citation statements)

References 46 publications

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“…On the other hand, patterned SiNW arrays, usually prepared using nanosphere lithography or other patterning techniques, lead to much uniform Raman intensity distribution on a SERS substrate, with typical RSD values of ≈10% or below. [247,296,302] Regarding the noble metal nanostructures (normally nanoparticles) for the decoration of SiNW array, either solution reduction of metal salts (AgNO 3 , HAuCl 4 ) [298,300,301,303,304] or direct vacuum deposition of metals onto SiNWs [296,305,306] can be used. It should be noted that the SERS enhancement may be higher and uniform (smaller RSD) in metal film conformally coated onto SiNW [299] than those for metal nanoparticle decorated SiNWs, unless careful optimization of SiNWs (diameter, spacing, and length) and inter-particle gap in metal nanoparticles.…”

Section: Bioapplicationsmentioning

confidence: 99%

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

Srivastava

Khang

2021

Advanced Materials

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classified into two common approaches: bottom-up chemical synthesis, such as vapor-liquid-solid growth, [16][17][18][19][20] and topdown fabrication schemes. [21][22][23] This review will focus on the top-down fabrication of Si structures using a wet chemical etching technique aided with a metal catalyst, called metal-assisted chemical etching (MaCE). [24][25][26][27][28][29][30][31][32] In comparison with top down fabrication methods based on dry etching using a reactive plasma in vacuum, MaCE is less expensive and less complex. [33][34][35] MaCE is a nano-scale reductionoxidation (redox) process that usually occurs in aqueous solution where the sample to be etched is in contact with the etchant. MaCE is a simple, cost-effective, and versatile method to produce Si nanostructures; due to these attractive features, there have been many good review articles published on the process. [36][37][38][39][40][41][42] With two-decades of research of the MaCE and its innovative variations, recent studies have focused on the various applications of Si nanostructures prepared by MaCE, including photovoltaics, [43,44] thermoelectrics and piezoelectric nanogenerators, [45] energy storage, [46][47][48] nanophotonics and optoelectronics, [49] and biosensors and biomedical applications. [50][51][52] In this review, we provide an overview of the recent advances in MaCE processes and their novel applications. To differentiate this review from previous review articles, the main emphasis is on the recently developed novel MaCE processes and the macroscale structuring of Si by MaCE. We begin the review by describing new MaCE processes, particularly catalysts for MaCE. In contrast to well-known noble metal catalysts, such as Ag, Au, and Pt, carbon-based catalysts, such as graphene, graphene oxide, and carbon nanotubes, have been successfully applied as catalysts for MaCE. In addition, TiN has been found to be a catalyst for MaCE, making the whole process CMOS-compatible. Different types of etch additives, such as various alcohols and chlorides, have also been discussed, which enhance etch uniformity by increasing the wettability of etchants and suppressing the random diffusion of excessive (holes) h + by trapping them for better etch control. Recent novel variations of the MaCE process have been introduced, such as MaCE with externally applied electric or magnetic fields. The external field has a profound effect on the output of MaCE, by controlling the etch directionality and etch rate. In addition, MaCE can be combined with unconventional patterning techniques, StructuringSi, ranging from nanoscale to macroscale feature dimensions, is essential for many applications. Metal-assisted chemical etching (MaCE) has been developed as a simple, low-cost, and scalable method to produce structures across widely different dimensions. The process involves various parameters, such as catalyst, substrate doping type and level, crystallography, etchant formulation, and etch additives. Careful optimization of these parameters is the key to the succe...

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Section: Bioapplicationsmentioning

confidence: 99%

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

Srivastava

Khang

2021

Advanced Materials

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“…For numerical simulations, EMEF is much more appropriate than the EF presented at Eq. ( 4) and is vastly utilized in the SERS context [34][35][36] which is also applied in this article. All numerical simulations throughout the article are performed with the FDTD method.…”

Section: Theory and Modelingmentioning

confidence: 99%

Tuning the localized surface plasmon resonance of “core-shell Ag nanoparticles on dielectric substrates” to near-infrared window: applications to surface-enhanced Raman spectroscopy

Salimian¹,

Soofi²

2020

Optica Applicata

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In this article, plasmonic characteristics of SiO2-Ag and hollow core Ag nanoparticles placed on dielectric substrates are investigated and tuned to the NIR wavelength spectrum for biological applications. It is shown that by placing the core-shell Ag nanoparticles on a dielectric substrate and exciting the normal plasmon mode of the nanoparticle, it is possible to obtain strong plasmon resonances at wavelengths as long as λ = 700 nm which exhibits a red shift of more than 300 nm compared to the resonance of freestanding pure Ag nanoparticles at which normal plasmon resonance wavelength shows a sensitivity of approximately 100 nm/RIU in respect to the substrate refractive index change. “SiO2-Ag and hollow core Ag nanoparticles on silicon” are optimized to exhibit a strong normal plasmon resonance at λ = 633 nm while preserving the plasmonic field enhancement intact. Finally, a three dimensional substrate for surface-enhanced Raman spectroscopy (SERS) is designed and numerically investigated. The substrate is composed of Si nanorod array decorated with the designed nanoparticles which exhibits superior characteristics such as a uniform and gapless field enhancement and an electromagnetic enhancement factor of more than 3 × 106, an order of magnitude higher than the enhancement factor for a similar structure decorated with Au nanoparticles.

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“…5b with metal-assisted chemical etching (MACE) or laser excimer method. Figure 6 shows exemplary SEM images of such nanowires from our preliminary fabrication trials using the fabrication protocols detailed at [20][21][22] and [23] for MACE and laser excimer, respectively. In Fig.…”

Section: Fabrication Proceduresmentioning

confidence: 99%

Vertical silicon nanowire-based racetrack resonator optical sensor

et al. 2019

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We propose a highly sensitive optical sensor which is built from silicon nanowires. The silicon nanowires are arranged to form a ring resonator. The silicon nanowires cladding and voids are filled with the analyte. The sensor has a small footprint of 16 μm × 16.5 μm. The insertion loss of the sensor is only 0.4 dB, while it is characterized by its high sensitivity of 430 nm/ RIU. As a biosensor, our device showed a 100 nm/RIU sensitivity when a thin biolayer of 10 nm thickness is attached to the silicon nanowire structures.

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Silicon-Based SERS Substrates Fabricated by Electroless Etching

Cited by 24 publications

References 46 publications

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

Tuning the localized surface plasmon resonance of “core-shell Ag nanoparticles on dielectric substrates” to near-infrared window: applications to surface-enhanced Raman spectroscopy

Vertical silicon nanowire-based racetrack resonator optical sensor

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