Using HCl to Control Silver Dissolution in Metal-Assisted Chemical Etching of Silicon

Williams, Max O.; Jervell, Ada L. H.; Hiller, Daniel; Zacharias, Margit

doi:10.1002/pssa.201800135

Cited by 5 publications

(2 citation statements)

References 39 publications

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“…At pH 4.5, around 70 wt.% of silver was lost, while at basic pH the loss was 42 wt.% (in the case of using pH 9) and 30 wt.% using pH 14. The acidification of the aqueous medium using HCl led to losses of more than 70 wt.% probably because the dissolution of silver is promoted under acidic conditions and the solubility of PEI increased [ 59 , 60 , 61 , 62 ]. Under alkaline conditions, the protonation of the amino groups is lost and therefore the interaction with the fabrics as well as with the AgNPs would vanish.…”

Section: Resultsmentioning

confidence: 99%

Silver Nanoparticles–Polyethyleneimine-Based Coatings with Antiviral Activity against SARS-CoV-2: A New Method to Functionalize Filtration Media

et al. 2022

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The use of face masks and air purification systems has been key to curbing the transmission of SARS-CoV-2 aerosols in the context of the current COVID-19 pandemic. However, some masks or air conditioning filtration systems are designed to remove large airborne particles or bacteria from the air, being limited their effectiveness against SARS-CoV-2. Continuous research has been aimed at improving the performance of filter materials through nanotechnology. This article presents a new low-cost method based on electrostatic forces and coordination complex formation to generate antiviral coatings on filter materials using silver nanoparticles and polyethyleneimine. Initially, the AgNPs synthesis procedure was optimized until reaching a particle size of 6.2 ± 2.6 nm, promoting a fast ionic silver release due to its reduced size, obtaining a stable colloid over time and having reduced size polydispersity. The stability of the binding of the AgNPs to the fibers was corroborated using polypropylene, polyester-viscose, and polypropylene-glass spunbond mats as substrates, obtaining very low amounts of detached AgNPs in all cases. Under simulated operational conditions, a material loss less than 1% of nanostructured silver was measured. SEM micrographs demonstrated high silver distribution homogeneity on the polymer fibers. The antiviral coatings were tested against SARS-CoV-2, obtaining inactivation yields greater than 99.9%. We believe our results will be beneficial in the fight against the current COVID-19 pandemic and in controlling other infectious airborne pathogens.

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Section: Resultsmentioning

confidence: 99%

Silver Nanoparticles–Polyethyleneimine-Based Coatings with Antiviral Activity against SARS-CoV-2: A New Method to Functionalize Filtration Media

et al. 2022

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“…[126] Another useful additive for MaCE is chloride, such as HCl and NaCl. [127,128] These chlorides can easily dissociate into ions, and those ions interfere with reactive species in the MaCE. In Ag-based MaCE, it is well known that Ag catalyst can easily be dissolved by H 2 O 2 ; the dissolved Ag + ions sit at any exposed Si surface and start unwanted MaCE reaction there.…”

Section: Etch Additivesmentioning

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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Low Cost and High‐Aspect Ratio Micro/Nano Device Fabrication by Using Innovative Metal‐Assisted Chemical Etching Method

et al. 2019

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In this paper, the metal‐assisted chemical etching (MACE) method is presented along with the advantages of using this method. Large areas and a combination of large and narrow patterning areas are successfully produced by using metal meshes for MACE. Moreover, in order to exemplify this microfabrication technique, the authors demonstrate the fabrications of different microelectromechanical systems (MEMS) devices; from simple structure (micro‐cantilever) to a complex structure (capacitive silicon resonator). Micro‐cantilever beam with resonant frequency of 262 kHz and quality factor of 8100 is successfully fabricated using this technique. Narrow capacitive gap width together with silicon resonator structure is also microprocessed by MACE technique. For the capacitive resonator, nano gaps with 250 nm‐width and 7 μm‐height is successfully micro‐fabricated using MACE process on a silicon on insulator (SOI) wafer. The resonant peak of the fabricated device is found at 81.4 MHz with quality factor of 4000 and motional resistance of 89 kΩ. The MACE process is performed in the wet etching solution that enables the fabrication of anisotropic silicon structures. This paper demonstrates that MACE method could potentially replace dry etching technique currently used for the fabrication of various electronics and photonics devices and energy applications. Due to the ease of implementation and possibility of batch fabrication, MACE method is a promising technique for the manufacturing of a broad range of high‐quality Si‐based devices at low cost.

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Using HCl to Control Silver Dissolution in Metal-Assisted Chemical Etching of Silicon

Cited by 5 publications

References 39 publications

Silver Nanoparticles–Polyethyleneimine-Based Coatings with Antiviral Activity against SARS-CoV-2: A New Method to Functionalize Filtration Media

Silver Nanoparticles–Polyethyleneimine-Based Coatings with Antiviral Activity against SARS-CoV-2: A New Method to Functionalize Filtration Media

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

Low Cost and High‐Aspect Ratio Micro/Nano Device Fabrication by Using Innovative Metal‐Assisted Chemical Etching Method

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