Showing papers on "Isotropic etching published in 2022"
TL;DR: In this paper , an etching structure that exploits anisotropic charge carrier flow to enable high-throughput, external bias-free wet etching of high-aspect-ratio SiC micro/nano-structures is demonstrated.
Abstract: Wet etching of silicon carbide typically exhibits poor etching efficiency and low aspect ratio. In this study, an etching structure that exploits anisotropic charge carrier flow to enable high‐throughput, external‐bias‐free wet etching of high‐aspect‐ratio SiC micro/nano‐structures is demonstrated. Specifically, by applying a catalytic metal coating at the bottom surface of a SiC wafer while introducing patterned ultraviolet light illumination from its top surface, spatial charge separation across the wafer is achieved, i.e., photogenerated electrons are channeled to the bottom to participate in the reduction reaction of an oxidant in the etchant solution, while holes flow to the top to trigger oxidation of SiC and subsequent etching. Such design largely suppresses recombination‐induced charge losses, and when used in combination with a top metal catalyst mask, the structure yields a remarkable vertical etching rate of 0.737 µm min−1 and an aspect ratio of 3.2, setting new records for wet‐etching methods for SiC.
29 citations
TL;DR: In this article, fractionated chemical etching of porous Ti6Al4V Functionally Graded Porous Scaffolds (FGPS) with multiple immersions was investigated to facilitate trapped powder removal and reduce the surface roughness without critical degradation of the mechanical properties.
18 citations
TL;DR: In this article , the effect of chemical-etched surface texturing on Al/stainless steel wetting was investigated by the modified sessile drop method and the spreading mechanism was revealed by combining the identification of precursor films and interfacial microstructures with the analysis of spreading dynamics.
17 citations
TL;DR: In this article , a review focusing on the topic of "etching MOFs" is presented, which can be broadly classified into four categories including pore engineering, surface/facet modification, defect modification and self-templated conversion to layered metal hydroxides (LDHs).
17 citations
TL;DR: In this paper , a super-hydrophobic surface with intermetallic phases in AA3003 was fabricated via a chemical etching approach combined with stearic acid (STA) modification.
16 citations
TL;DR: In this article , the authors reviewed various etching methods reported for texturing multi-crystalline silicon (mc-Si) wafer solar cells under the light of basic reaction mechanism, general composition of chemicals used, merits, drawbacks, and the progress made towards their commercialization.
15 citations
TL;DR: In this article , fractionated chemical etching of porous Ti6Al4V Functionally Graded Porous Scaffolds (FGPS) with multiple immersions was investigated to facilitate trapped powder removal and reduce the surface roughness without critical degradation of the mechanical properties.
15 citations
TL;DR: In this paper , a two-step chemical etching method for preparing superhydrophobic surfaces on stainless steel substrates is proposed, where the stainless steel substrate is sequentially immersed in hydrochloric acid and ferric chloride solutions to create micro-nano structures, and then the surfaces are modified with low surface energy substances.
Abstract: A two-step chemical etching method for preparing superhydrophobic surfaces on stainless steel substrates is proposed. The stainless steel substrates were sequentially immersed in hydrochloric acid and ferric chloride solutions to create micro-nano structures, and then the surfaces were modified with low surface energy substances. Superhydrophobic surfaces with a contact angle of 159° and a sliding angle of 2° were prepared by varying the etching solution parameters. The fabricated superhydrophobic surfaces showed excellent stability and self-cleaning properties. This paper illustrates a low-cost and efficient chemical etching method that can be used for large-area surface fabrication.
11 citations
TL;DR: In this article , a chemical scissors strategy is developed by selectively removing unwanted metallic materials after excessive loading, which places more emphasis on the accurate matching between the strength of etching agent and the bond energies of metal-metal/metal substrate, thus enabling a higher loading up to 2.02 wt% even on bare substrate without any pre-treatment.
Abstract: Atomically dispersed metal catalysts often exhibit high catalytic performances, but the metal loading density must be kept low to avoid the formation of metal nanoparticles, making it difficult to improve the overall activity. Diverse strategies based on creating more anchoring sites (ASs) have been adopted to elevate the loading density. One problem of such traditional methods is that the single atoms always gather together before the saturation of all ASs. Here, a chemical scissors strategy is developed by selectively removing unwanted metallic materials after excessive loading. Different from traditional ways, the chemical scissors strategy places more emphasis on the accurate matching between the strength of etching agent and the bond energies of metal-metal/metal-substrate, thus enabling a higher loading up to 2.02 wt% even on bare substrate without any pre-treatment (the bare substrate without any pre-treatment generally only has a few ASs for single atom loading). It can be inferred that by combining with other traditional methods which can create more ASs, the loading could be further increased by saturating ASs. When used for CH3 OH generation via photocatalytic CO2 reduction, the as-made single-atom catalyst exhibits impressive catalytic activity of 597.8 ± 144.6 µmol h-1 g-1 and selectivity of 81.3 ± 3.8%.
10 citations
TL;DR: In this paper , the micro-nano structures of aluminum alloys after chemical etching were compared, and the results showed that the surface microscopic morphology of different aluminum alloy after etching differed significantly.
10 citations
TL;DR: In this article , the effects of surface modification on the properties of the Sb2(S,Se)3 film as well as its solar cell performance were investigated, and it was shown that chemical etching performed on Sb 2 S,Se 3 film using potassium fluoride aqueous solution not only improved the crystallinity and uniformity of Sb S, Se 3 film but also decreased the interfacial defects, leading to a reduced carrier recombination loss of the device.
TL;DR: In this paper , the role of mechanically driven defects in wet etching was systematically investigated toward promoting controllable wet chemical etching of monocrystalline Si, including dislocations and stacking faults.
Abstract: Wet chemical etching is essential not only for processing silicon (Si) wafers but also for forming diverse structures, significantly promoting the development of the semiconductor industry. However, tight control of etched topography at the nanoscale and even atom-scale in a controllable and reproducible fashion can be hardly achieved in either laboratory research or industrial production, seriously hindering further enhancement of high-performance Si-based electronic devices. Herein, the roles of mechanically driven defects in wet etching were systematically investigated toward promoting controllable wet etching of monocrystalline Si. The role of antietching of mechanically driven amorphous Si (a-Si) and the role of promoting etching of distorted Si (including dislocations and stacking faults) were revealed in anisotropic or isotropic etchants. It was also found that the nucleation of nanocrystals in the a-Si area with increasing contact pressure can lead to deactivation of the antietching mask, and the required contact pressure for deactivation in KOH and tetramethyl ammonium hydroxide solutions was much higher than that in HF/HNO3 mixtures. The selective etching mechanisms for every defect including a-Si, distorted Si, and nanocrystals were further addressed down to the atom-scale based on the proposed dissolution model. This study provides insights into deeply understanding the role of defects in wet etching and pushes forward the idea of controllable wet chemical etching in the Si-based semiconductor industry.
TL;DR: Wang et al. as discussed by the authors proposed to reveal the subsurface damage (SSD) of 4H-SiC wafers by photo-chemical etching and identify the nature of SSD by molten-alkali etching.
Abstract: In this work, we propose to reveal the subsurface damage (SSD) of 4H-SiC wafers by photo-chemical etching and identify the nature of SSD by molten-alkali etching. Under UV illumination, SSD acts as a photoluminescence-black defect. The selective photo-chemical etching reveals SSD as the ridge-like defect. It is found that the ridge-like SSD is still crystalline 4H-SiC with lattice distortion. The molten-KOH etching of the 4H-SiC wafer with ridge-like SSD transforms the ridge-like SSD into groove lines, which are typical features of scratches. This means that the underlying scratches under mechanical stress give rise to the formation of SSD in 4H-SiC wafers. SSD is incorporated into 4H-SiC wafers during the lapping, rather than the chemical mechanical polishing (CMP).
TL;DR: In this paper , three common bSi fabrication techniques, i.e., plasma etching, metal-assisted chemical etching (MACE), and femtosecond-laser etching are compared.
Abstract: In semiconductor manufacturing, black silicon (bSi) has traditionally been considered as a sign of unsuccessful etching. However, after more careful consideration, many of its properties have turned out to be so superior that its integration into devices has become increasingly attractive. In devices where bSi covers the whole wafer surface, such as solar cells, the integration is already rather mature and different bSi fabrication technologies have been studied extensively. Regarding the integration into devices where bSi should cover only small selected areas, existing research focuses on device properties with one specific bSi fabrication method. Here, we fabricate bSi patterns with varying dimensions ranging from millimeters to micrometers using three common bSi fabrication techniques, i.e., plasma etching, metal-assisted chemical etching (MACE) and femtosecond-laser etching, and study the corresponding fabrication characteristics and resulting material properties. Our results show that plasma etching is the most suitable method in the case of $\mu \text{m}$ -scale devices, while MACE reaches surprisingly almost the same performance. Femtosecond-laser has potential due to its maskless nature and capability for hyperdoping, however, in this study its moderate accuracy, large silicon consumption and spreading of the etching damage outside the bSi region leave room for improvement.
TL;DR: In this article , a simple method was adopted to prepare inverted pyramids with different sizes by varying the ρ value (ρ = [HF]/([HF]+[H2O2]) of Cu metal assisted chemical etching (Cu-MACE) solution.
TL;DR: In this paper , a hierarchical labyrinth-like structure of superhydrophilic aluminum alloy (AA 6063) was fabricated using a facile and environmentally benign chemical etching method, and the patterned samples were functionalized by stearic acid molecules to obtain super-hydrophobic samples with water contact angle (CA) >160°.
Abstract: In this work, we fabricated superhydrophilic aluminum alloy (AA 6063) with a hierarchical labyrinth-like structure using a facile and environmentally benign chemical etching method. The patterned samples were functionalized by stearic acid molecules to obtain superhydrophobic samples with water contact angle (CA) >160°, at optimum conditions. Although the superhydrophobic samples initially exhibited up to two orders of magnitude better corrosion resistance compared to as-received samples, their corrosion performance and CA gradually reduced upon prolonged exposure to 3.5 wt% NaCl solution. Hence, we experimetally show that the initial high CA in superhydrophobic surface layers cannot be used as a measure of their long-term corrosion stability.
TL;DR: In this article , a detailed review of glass etchings is presented, including different etch mechanisms including etch parameters and surface microstructure of the etched glass, and the use of HF buffered with NH4F solutions to improve the quality of the etch surface.
TL;DR: In this article, a novel and highly efficient isotropic etching polishing (IEP) technique electrochemically polished flat and complex 3D printed Inconel 718 (IN718) parts.
TL;DR: In this article , a facile mask-free confined-etching strategy is reported for intrinsic wettable surface patterning, enabling the chemical etching of setting locations and efficient fabrication of complex patterns.
Abstract: Abstract Anisotropic functional patterned surfaces have shown significant applications in microfluidics, biomedicine and optoelectronics. However, surface patterning relies heavily on high-end apparatuses and expensive moulds/masks and photoresists. Decomposition behaviors of polymers have been widely studied in material science, but as-created chemical and physical structural changes have been rarely considered as an opportunity for wettability manipulation. Here, a facile mask-free confined-etching strategy is reported for intrinsic wettable surface patterning. With printing technology, the surface wetting state is regulated, enabling the chemical etching of setting locations and efficient fabrication of complex patterns. Notably, the created anisotropic patterns can be used for realizing water-responsive information storage and encryption as well as fabricating flexible electrodes. Featuring advantages of simple operation and economic friendliness, this patterning approach brings a bright prospect in developing functional materials with versatile applications.
TL;DR: In this article , metal-assisted chemical etching (MACE) and three-dimensional electrochemical axial lithography (3DEAL) were used to structure and pattern SiNW arrays in three dimensions, providing substrate with spatially controlled optical properties.
Abstract: Vertically aligned silicon nanowire (VA-SiNW) arrays can significantly enhance light absorption and reduce light reflection for efficient light trapping. VA-SiNW arrays thus have the potential to improve solar cell design by providing reduced front-face reflection while allowing the fabrication of thin, flexible, and efficient silicon-based solar cells by lowering the required amount of silicon. Because their interaction with light is highly dependent on the array geometry, the ability to control the array morphology, functionality, and dimension offers many opportunities. Herein, after a short discussion about the remarkable optical properties of SiNW arrays, we report on our recent progress in using chemical and electrochemical methods to structure and pattern SiNW arrays in three dimensions, providing substrates with spatially controlled optical properties. Our approach is based on metal-assisted chemical etching (MACE) and three-dimensional electrochemical axial lithography (3DEAL), which are both affordable and large-scale wet-chemical methods that can provide a spatial resolution all the way down to the sub-5 nm range.
TL;DR: In this article, a simple method was adopted to prepare inverted pyramids with different sizes by varying the ρ value (ρ = [HF]/([HF]+[H2O2]) of Cu metal assisted chemical etching (Cu-MACE) etching solution.
TL;DR: In this paper , a facile mask-free confined-etching strategy is reported for intrinsic wettable surface patterning, enabling the chemical etching of setting locations and efficient fabrication of complex patterns.
Abstract: Abstract Anisotropic functional patterned surfaces have shown significant applications in microfluidics, biomedicine and optoelectronics. However, surface patterning relies heavily on high-end apparatuses and expensive moulds/masks and photoresists. Decomposition behaviors of polymers have been widely studied in material science, but as-created chemical and physical structural changes have been rarely considered as an opportunity for wettability manipulation. Here, a facile mask-free confined-etching strategy is reported for intrinsic wettable surface patterning. With printing technology, the surface wetting state is regulated, enabling the chemical etching of setting locations and efficient fabrication of complex patterns. Notably, the created anisotropic patterns can be used for realizing water-responsive information storage and encryption as well as fabricating flexible electrodes. Featuring advantages of simple operation and economic friendliness, this patterning approach brings a bright prospect in developing functional materials with versatile applications.
TL;DR: In this paper , the anisotropic wet etching of sputtered AlN and Sc 0.2 Al 0.8 N thin films was investigated and the lateral etching was reduced to 35-220 nm by optimizing mask deposition and thermal annealing.
TL;DR: In this paper , a simple method to fabricate the silicon pyramid on the silicon substrate via a chemical etching method was demonstrated, which can provide suitable geometric structures to deposit silver nanoparticles with better anti-aggregation stability to apply surfaceenhanced Raman spectroscopy (SERS) substrates via the ion-sputtering method.
TL;DR: The Prussian blue analogues are promising pre-catalysts for oxygen evolution reaction (OER) and the in-situ reconstructed metal oxyhydroxides during OER are regarded as the real active sites as discussed by the authors .
Abstract: Prussian blue analogues (PBAs) are promising pre-catalysts for oxygen evolution reaction (OER) and the in-situ reconstructed metal oxyhydroxides during OER are regarded as the real active sites. However, most of...
TL;DR: In this article , a facile one-step chemical etching and modification with 1H,1H,2H, 2H-Perfluorodecyltriethoxysilane was proposed to fabricate superamphiphobicity.
Abstract: Aluminum alloys (Al alloys) are susceptible to corrosion due to their high chemical activity, particularly in complicated marine surroundings. Liquid-repelling Al alloy surfaces with enhanced corrosion resistance were prepared via a facile one-step chemical etching and modification with 1H,1H,2H,2H-Perfluorodecyltriethoxysilane. Results indicated that the fabricated sample with step-like micro/nanostructures exhibited excellent superamphiphobicity, which the static contact angles achieved 162°, 158°, and 152° for water, ethylene glycol, and hexadecane, respectively. Furthermore, electrochemical tests shed light on that the superamphiphobic surface fabricated greatly improved the anti-corrosion performance and durability of the substrate in 3.5 wt% NaCl aqueous solution. The whole process requires no special equipment, providing a facile and environment-friendly method to fabricate superamphiphobic surfaces.
TL;DR: In this paper , the fabrication of silicon (Si) nanowires (NWs) arrays by using Si (1 0 0) wafer as substrate, by metal assisted chemical etching (MACE) method is presented.
TL;DR: In this paper , an etchant solution based on a Potassium Hydroxide, water, and isopropanol mixture was used to produce a high aspect ratio (up to 1:1000), straight and spiral microfluidic channels which are embedded inside a volume of glass.
Abstract: Selective laser etching (SLE) is a technique that allows the fabrication of arbitrarily shaped glass micro-objects. In this work, we show how the capabilities of this technology can be improved in terms of selectivity and etch rate by applying an etchant solution based on a Potassium Hydroxide, water, and isopropanol mixture. By varying the concentrations of these constituents, the wetting properties, as well as the chemical reaction of fused silica etching, can be changed, allowing us to achieve etching rates in modified fused silica up to 820 μm/h and selectivity up to ∼3000. This is used to produce a high aspect ratio (up to 1:1000), straight and spiral microfluidic channels which are embedded inside a volume of glass. Complex 3D glass micro-structures are also demonstrated.