One-step Etching Process Research Articles

Controllable Fabrication of Silicon Solar Cells with Inverted or Upright Pyramid Structures by a One-Step Copper Catalysis Method

Silicon has garnered significant attention as the primary material for solar cell preparation. Traditional alkaline etching solutions are limited to creating an upright pyramid structure on monocrystalline silicon surfaces. However, research indicates that an inverted pyramid structure exhibits superior light-trapping properties compared to the upright pyramid structure. In this study, we employed a one-step copper ion metal-assisted chemical etching process to fabricate an inverted pyramid structure on monocrystalline silicon wafers. This method allows for the customization of either inverted or upright pyramid structures by adjusting the concentration of specific solution components. Characterization of the textured silicon wafers reveals that the inverted pyramid structure exhibits lower reflectivity than both the upright pyramid structure and polished silicon. By integrating this texturing technique into the solar cell production line, we successfully produced solar cells with both inverted and upright pyramid structures. Evaluation of various solar cell parameters demonstrates that the inverted pyramid structure outperforms the upright pyramid structure, showcasing lower reflectivity and higher photoelectric conversion efficiency.

Surface modification of silicon nanowires via drop-casting for high-performance Li-ion battery electrodes: SiNWs decorated with molybdenum oxide nanoparticles

The functionalization of molybdenum oxide (MoO3) nanoparticles is presented as a method to significantly enhance the cycling stability of lithium-ion battery (LIB) anodes based on silicon nanowire (SiNW) arrays. Transition-metal oxides have emerged as promising candidates for advanced anode materials in modern Li-ion batteries. In this study, we explore a novel approach involving the deposition of MoO3 nanoparticles via unique drop-casting technique onto pre-fabricated SiNW arrays, fabricated using a straightforward one-step metal-assisted chemical etching (MACE) process. The primary objective is to assess their potential suitability as anode materials for Li-ion batteries. Our methodology entails the top-down synthesis of binder-free hybrid electrodes, achieved by depositing Mo oxides nanostructures onto SiNW arrays through a combination of drop-casting and thermal annealing processes. The resulting MoO3@SiNWs hybrid structure exhibits distinctive and specialized attributes, including exceptional structural resilience, diminutive particle dimensions, and a porous configuration. These features effectively enhance electron and ion accessibility at the electrode-electrolyte interface.Electrochemical assessments reveal that the MoO3@SiNWs hybrids exhibit superior lithium storage performance compared to bare SiNW electrodes. Particularly under high current densities, MoO3 nanoparticles deposited via drop-casting technique demonstrate improved cycling stability and increased capacity. The enhanced electrochemical characteristics are primarily ascribed to the synergistic effects between the MoO3 nanoparticles and SiNW arrays. The findings of this study strongly suggest that the MoO3@SiNWs hybrid structure holds substantial promise as anode materials for high-performance energy storage devices.

Facilely etching of superhydrophobic surface with regular mulriple hierarchical micro-nano structures for crowning wettability

Nowadays, achieving highly effective superhydrophobic surfaces on chemically active magnesium alloys via a straightforward and efficient etching method remains a formidable task. In this study, we have successfully fabricated regular mulriple hierarchical micro-nano structures on AZ91D substrates through a one-step etching process. The resultant nano-chrysanthemums exhibit remarkable biomimicry wherein the extended nanostructures and the protrusions on them further enhance the air–liquid interface contact area. Subsequent to the modification, the contact and sliding angles of the samples achieved exceptional performance surpassing that of previous etching techniques. Furthermore, this low adhesion surface demonstrates commendable chemical stability even when exposed to air, chemically aggressive solutions (including strong acids and bases), and cyclic icing/melting treatments. Moreover, this versatile superhydrophobic surface exhibits exceptional resistance to various forms of contamination. The method employed to generate such advantageous superhydrophobic surfaces necessitates minimal equipment complexity and boasts substantial advantages in terms of affordability and efficiency. These characteristics not only confer promising prospects for widespread application but also render it suitable for large-scale industrial production.

Comparison of random upright pyramids and inverted pyramid photonic crystals in thin crystalline silicon solar cells: An optical and morphological study

The potential of enabling a wide range of applications with lightweight, flexible, thin silicon photovoltaic (PV) devices has led to research interest in various light-trapping technologies for thin silicon absorbers. Herein, using both experiments and photonic modelling, we present a detailed comparison between random pyramid texturing and inverted pyramid photonic crystal patterning in thin silicon vis-à-vis light trapping. In particular, we investigate the potential of uniform single-dimension periodic structures in contrast to conventional multi-dimensional random structures for high broadband absorption efficiency in ultra-thin silicon. We find that inverted pyramid photonic crystals cause a large increase in optical path length especially for long wavelength photons due to strong wave interference producing exceptionally high absorption and so does random pyramids though with slightly lower absorption than that of photonic crystals. On the other hand, the random pyramids, fabricated via a one-step etching process with feature sizes ranging from sub-micron to 4 µm, have higher absorption at short wavelengths due to their multi-dimensional size distribution. Overall, we find that random textured pyramids appropriately fabricated can yield a comparable ideal photocurrent density to that by photonic crystals for 10 µm thick silicon.

ZIF-67 derived magnetic nanoporous carbon coated by poly(m-phenylenediamine) for hexavalent chromium removal

• The new magnetic nanocomposites (MNC@PmPD) was synthesized in situ polymerization. • The maximum adsorption capacity of MNC@PmPD 2 for Cr(VI) was 240.44 mg·g -1 . • The possible adsorption and reduction mechanism of Cr(VI) was proposed. A novel core–shell magnetic nanomaterial is synthesized to adsorb highly toxic chromium (Cr(VI)) from water. Cobalt-based MOF (ZIF-67) is used as precursor to prepare magnetic nanoporous carbon (MNC) by one-step carbonization and etching process. Poly(m-phenylenediamine) (PmPD) is assembled on the surface of MNC by in-situ polymerization at low temperature. The magnetic MNC@PmPDs with definite core-shell structure are successfully fabricated. The adsorption capacity of MNC@PmPD 2 for Cr(VI) can reach 240.44 mg·g - 1 , much higher than the bare MNC (126.27 mg·g - 1 ). The core–shell structure improves the adsorption efficiency of the PmPD shell to 445.64 mg·g - 1 , compared with that of bare PmPD (332 mg·g - 1 ). The MNC@PmPD 2 can be easily separated from the solution by the advantage of magnetic-core. Moreover, the prepared MNC@PmPD 2 exhibits high stability during adsorption with negligible Co leaching and structural decomposition. The mechanism of Cr(VI) removal is considered to be based on the synergistic effect of adsorption and reduction. The removal rate of Cr(VI) follows the pseudo-second-order model and the adsorption isotherm data fits well to the modified Langmuir isothermal model. The excellent adsorption capacity, easy magnetic separation and high structure stability indicate a promising application of MNC@PmPD for Cr(VI) remediation in wastewater.

Preparation of hollow nanoparticles with controllable diameter by one-step controlled etching of microporous silica particles using an ammonia-based etchant

Hollow silica particles with spherical morphology and controllable diameter (100–250 nm) were successfully prepared by one-step etching process using an ammonia-based etchant under mild etching conditions. First, microporous silica particles with a low degree of condensation were synthesized by modified Stöber method using low concentration of ammonia solution. Then, the microporous silica particles were coated with polydimethyldiallylammonium chloride (PDDA). The PDDA-coated particles were treated with an aqueous ammonia solution to obtain hollow silica nanospheres. In this study, the condensation degree of silica particles, PDDA concentration, ammonia etchant concentration, and etching temperature were found to have significant impact on the morphology of hollow silica nanoparticles. Adsorption studies showed that the hollow silica particles could be efficiently used for the immobilization of bovine serum albumin.

Fabrication of Hydrophobic Ni Surface by Chemical Etching.

Hydrophobic surfaces were successfully fabricated on pure nickel substrates by a one-step chemical etching process with different acidic solutions. The static water contact angle (SCA) of the etched Ni surfaces reached higher than 125°, showing excellent hydrophobicity. The examination of surface chemical compositions implied that there were almost no polar moieties on the surface after chemical etching, except part of the surface was oxidized. After chemical etching, the nickel surfaces became much rough with packed terrace-/crater-/thorn-like clusters. According to the analysis of surface composition and morphology, the hydrophobicity was evidently attributed to the rough microstructures on the etched Ni surface. The best hydrophobicity on Ni surface was produced with the SCAs as high as 140.0° by optimizing the etching time and etchants. The results demonstrate that it is possible to construct hydrophobic surfaces on hydrophilic substrates by tailoring the surface microstructure using a simple chemical etching process without any further hydrophobic modifications by low surface energy materials.

Self-organized nano-scale multilayer coating on SiC fibers obtained by phosphating

Ceramic matrix composites (CMC) combine refractory and structural properties, with a damage-tolerant behavior ensured by an interphase material, usually deposited on fibers. Unfortunately, surface deposition does not prevent contacts between fibers, which are responsible for the premature collective failure of fiber clusters and therefore for limited lifetime. Recently, a workaround has been proposed by transforming the surface of the fibers itself into a continuous monolayer coating. Here we describe an SiC fiber etching process by phosphoric acid vapors at atmospheric pressure and intermediate temperature (600–700 °C), leading to an in situ multilayer transformation into a (carbon/silicophosphate)n coating, n ranging from unity to tens and layers thickness from 100 to 300 nm. The carbon layers are micro/mesoporous carbide-derived carbon (CDC) tubes with micrometric radii. This one-step etching process gives opportunity to create layered materials containing CDC even on complex geometries such as fabrics.

Determination of trace uric acid in serum using porous graphitic carbon nitride (g-C3N4) as a fluorescent probe.

Porous graphitic carbon nitride (g-C3N4) was prepared by a one-step acid etching and ultrasonication process. It is found that the strong blue fluorescence of g-C3N4 (with excitation/emission maxima at 320/400nm) is fairly selectively quenched by uric acid (UA). The morphology and chemical structure of the nanoporous g-C3N4 were characterized by XRD, TEM and FTIR. Quenching studies and Stern-Volmer plots reveal two UA concentration ranges of different quenching efficiency. The first extends from 50 to 500nM, the other from 0.5 to 10μM. The limit of detection is 8.4nM. The two quenching processes are attributed to both dynamic and static quenching. The porous g-C3N4 probes were applied to the determination of UA in (spiked) human serum and human plasma, and the results were as good as those obtained with UA standard solutions. These data illustrate that g-C3N4 can be used to selectively and sensitively quantify trace levels of UA even in a complex environment. Graphical abstract Porous graphite nitride carbon (g-C3N4) is shown to be a viable fluorescent probe for uric acid (UA) viaboth dynamic and static quenching. The electron transfer of carbon nitride is represented by the arrows; hν is the incident light; PL is the fluorescence emission.

Hybrid black silicon solar cells textured with the interplay of copper-induced galvanic displacement

Metal-assisted chemical etching (MaCE) has been widely employed for the fabrication of regular silicon (Si) nanowire arrays. These features were originated from the directional etching of Si preferentially along <100> orientations through the catalytic assistance of metals, which could be gold, silver, platinum or palladium. In this study, the dramatic modulation of etching profiles toward pyramidal architectures was undertaken by utilizing copper as catalysts through a facile one-step etching process, which paved the exceptional way on the texturization of Si for advanced photovoltaic applications. Detailed examinations of morphological evolutions, etching kinetics and formation mechanism were performed, validating the distinct etching model on Si contributed from cycling reactions of copper deposition and dissolution under a quasi-stable balance. In addition, impacts of surface texturization on the photovoltaic performance of organic/inorganic hybrid solar cells were revealed through the spatial characterizations of voltage fluctuations upon light mapping analysis. It was found that the pyramidal textures made by copper-induced cycling reactions exhibited the sound antireflection characteristics, and further achieved the leading conversion efficiency of 10.7%, approximately 1.8 times and beyond 1.2 times greater than that of untexturized and nanowire-based solar cells, respectively.

Self-Assembled Nanofeatures in Complex Three-Dimensional Topographies via Nanoimprint and Block Copolymer Lithography Methods.

Achieving ultrasmall dimensions of materials and retaining high throughput are critical fabrication considerations for nanotechnology use. This article demonstrates an integrated approach for developing isolated sub-20 nm silicon oxide features through combined “top-down” and “bottom-up” methods: nanoimprint lithography (NIL) and block copolymer (BCP) lithography. Although techniques like those demonstrated here have been developed for nanolithographic application in the microelectronics processing industry, similar approaches could be utilized for sensor, fluidic, and optical-based devices. Thus, this article centers on looking at the possibility of generating isolated silica structures on substrates. NIL was used to create intriguing three-dimensional (3-D) polyhedral oligomeric silsesquioxane (POSS) topographical arrays that guided and confined polystyrene-block-poly(dimethylsiloxane) (PS-b-PDMS) BCP nanofeatures in isolated regions. A cylinder forming PS-b-PDMS BCP system was successfully etched using a one-step etching process to create line-space arrays with a period of 35 nm in confined POSS arrays. We highlight large-area (>6 μm) coverage of line-space arrays in 3-D topographies that could potentially be utilized, for example, in nanofluidic systems. Aligned features for directed self-assembly application are also demonstrated. The high-density, confined silicon oxide nanofeatures in soft lithographic templates over macroscopic areas illustrate the advantages of integrating distinct lithographic methods for attaining discrete features in the deep nanoscale regime.

Nanotexturing of Conjugated Polymers via One-Step Maskless Oxygen Plasma Etching for Enhanced Tunable Wettability.

A one-step maskless oxygen plasma etching process is investigated to nanopattern conjugated polymer dodecylbenzenesulfonate doped polypyrrole (PPy(DBS)) and to examine the effects of nanostructures on the inherent tunable wettability of the surface and the droplet mobility. Etching characteristics such as the geometry and dimensions of the nanostructures are systematically examined for the etching power and duration. The mechanism of self-formation of vertically aligned dense-array pillared nanostructures in the one-step maskless oxygen plasma etching process is also investigated. Results show that lateral dimensions such as the periodicity and diameter of the pillared nanostructures are insensitive to the etching power and duration, whereas the length and aspect ratio of the nanostructures increase with them. X-ray photoelectron spectroscopy analysis and thermal treatment of the polymer reveal that the codeposition of impurities on the surface resulting from the holding substrate is the primary reason for the self-formation of nanostructures during the oxygen plasma etching, whereas the local crystallinity subject to thermal treatment has a minor effect on the lateral dimensions. Retaining the tunable wettability (oleophobicity) for organic droplets during the electrochemical redox (i.e., reduction and oxidization) process, the nanotextured PPy(DBS) surface shows significant enhancement of droplet mobility compared to that of the flat PPy(DBS) surface with no nanotexture by making the surface superoleophobic (i.e., in a Cassie-Baxter wetting state). Such enhancement of the tunable oleophobicity and droplet mobility of the conjugated polymer will be of great significance in many applications such as microfluidics, lab-on-a-chip devices, and water/oil treatment.

One-step synthesis of Au-coated porous silicon as a surface enhanced Raman scattering substrate for biomolecule detection

Porous silicon (pSi) coated with gold (Au) was synthesized by a one-step electrochemical etching process without any post treatment. The porous nature was confirmed by scanning electron microscopy (SEM) as well as Raman and photoluminescence spectroscopy. The surface enhanced Raman spectroscopic (SERS) sensing performance of Au-coated pSi (Au-pSi) was compared with uncoated pSi by using rhodamine 6G dye as the analyte. The bio-sensing performance of Au-pSi was evaluated using bovine serum albumin (BSA) protein as the analyte. The Au-pSi shown better sensitivity for R6G and BSA as compared to pSi.

Redesigned t-PFF-v device fabricated with one-step anisotropic chemical wet etching process: enhanced separation efficiency for colloidal particles in continuous-mode

A pinched flow fractionation device with trapezoid-shaped pinched segment and cross-flow side channels (t-PFF-v) was redesigned and fabricated with a one-stop anisotropic chemical wet etching process and its enhanced separation capability was demonstrated for spherical polystyrene (PS) particles with diameter ranges of 2–8 µm. The tilted sidewalls and vertical focusing channels of the t-PFF-v device led to an improved separation resolution (Rm,n) via enhanced separation distance of PS particles at the pinched segment (Δxm,n) and reduced effluent particle distribution width (sn). Using this t-PFF-v device with Wp (pinched segment width) of 25 µm, PS particles with diameters of 4, 6, and 8 µm were simultaneously separated with good separation resolution (R4,6 = 3.2 and R6,8 = 3.4). Moreover, by adapting even smaller pinched segment width (Wp = 15 µm), PS particles with diameters of 2 and 4 µm, not well separated in the previous studies, were clearly separated with 9.5-fold improvement in R2,4 compared with the normal PFF device (n-PFF). The effects of inlet flow rate ratio (Q2/Q1) on the separation efficiency were also carefully investigated and provided additional insight on the separation processes within the pinched segment of t-PFF-v device. The drain flow through the cross-flow v-channels helps better alignment of particles at the sidewall of pinched segment and resulted in significantly reduced distribution of effluent particles, even under the operating conditions with low Q2/Q1 values.

Double-textured ZnO:Al films obtained by a one-step etching method for enhanced light trapping

Double-textured ZnO:Al (AZO) transparent conducting films with good optoelectronic characteristics and enhanced light trapping ability were prepared by a method including deposition, etching and re-deposition, and only one-step etching process was adopted during the whole process. The effects of the one-step etching method on the structural and optoelectronic properties, surface morphology and light trapping ability of double-textured AZO films were studied systematically. Double-textured films were covered with uniformly and distinctly crater-like textured structure after the re-deposition. And double-textured AZO films exhibited higher haze values compared with the single-textured films. Effective enhancement of light trapping was obtained from the double-textured AZO films by the one-step etching method.

Conversion of Bulk Metallurgical Silicon into Photocatalytic Nanoparticles by Copper-Assisted Chemical Etching

Low-grade metallurgical silicon (MG-Si, purity ∼98%–99%, $1/kg) with annual production over six million tons is an attractive feedstock to produce active photocatalysts. However, MG-Si is known as an electronically dead material due to serious charge recombination associated with high metal impurity levels. Upgrading MG-Si close to solar grade is essential to achieve desired performance; nevertheless, the traditional silicon refinement process is cost ineffective, has high energy consumption, and causes environmental pollution. Here, we address this critical issue by employing a room-temperature one-step Cu-assisted chemical etching (CuACE) process, which successfully purifies MG-Si into active photocatalysts. We discover that the use of reducing agent (H3PO3) instead of commonly employed oxidant (H2O2) in the etchant system induces a novel phenomenon called “chemical cracking effect”. This effect significantly decreases the granularity of bulk MG-Si particles and simultaneously exposes fresh surfaces car...

All-metal structural color printing based on aluminum plasmonic metasurfaces.

An all-metal structural color printing platform based on aluminum plasmonic metasurfaces is proposed and demonstrated with high color performance using only a one-step etching process on aluminum surface. A wide visible color range is realized with the designed metallic square-shaped disk arrays by simply adjusting the geometrical parameters of the disk etching depth, disk width and unit cell period. The demonstrated all-metal microscale structural color printing on aluminum surface offers great potential for many practical color related applications.

Surface Modification of Porous Photoelectrode Using Etching Process for Efficiency Enhancement of ZnO Dye-Sensitized Solar Cells

Surface modification of porous ZnO photoelectrode using one- and two-step etching process is investigated for enhancing power conversion efficiency of ZnO dye-sensitized solar cells. ZnO films are modified by the diluted NH4OH solutions for one-step etching process and used as photoelectrode of dye-sensitized solar cells. Rough porous films are observed after one-step etching process. The fabricated cells based on the optimized one-step etched films show a significant increase in short-circuit current density. The short-circuit current density is directly changed with amount of dye adsorption, which is related to specific surface area. The etched films exhibit higher specific surface area over two times than nonetched films. Thus, the large specific surface area is the key success for increasing amount of dye adsorption. Internal electrochemical property of fabricated cells is also improved, indicating that chemical surface of ZnO films is modified in the same time. The DSSCs fabricated on two-step etched films with NH4OH and mixed acid HCl : HNO3show the maximum power conversion efficiency of 2.26%. Moreover, fill factor is also increased due to better redox process because of the formation of fine porous structure during the etching process. Therefore, these results implied that the roles of etching processes are improving specific surface area and fine porous formation which can provide better dye adsorption and redox process for dye-sensitized solar cell application.

Simple fabrication of micro-polygons and micro-honeycombs utilizing thermal deformation of monolayer colloidal crystals during reactive ion etching

Abstract The recent development of scaffolds with controlled topography has garnered a good deal of interest from researchers in various fields. In this paper, the authors focused on thermal deformation during reactive ion etching (RIE) of monolayers of two-dimensional polystyrene colloidal crystals as a simple method for the fabrication of such scaffolds. Various interesting structures, such as micro-polygons and micro-size honeycombs, were prepared in a one-step etching process. These interesting structures were fabricated on 3-μm-diameter particles but not on 1-μm-diameter particles because thermal deformation requires collective motion of bulk polymer. The balance of physical etching, chemical etching, and thermal deformation seems to have an important role in the fabrication of these micro structures.

A silicon-on-insulator polarization diversity scheme in the mid-infrared.

We propose a silicon-on-insulator (SOI) polarization diversity scheme in the mid-infrared wavelength range. In consideration of absorption loss in silicon dioxide (SiO2), the polarization splitter-rotator (PSR) is designed and optimized with silicon nitride (SiN) upper-cladding and SiO2 lower-cladding. This asymmetry allows the PSR, which consists of mode-conversion tapers and subsequent mode-sorting asymmetric Y-junctions, to be fabricated with a simple one-step etching process. Simulation shows that our PSR has good performance with low mode conversion loss (< 0.25 dB) and low crosstalk (< -18 dB) in a very large wavelength range from 4.0 μm to 4.4 μm. The PSR also exhibits large fabrication tolerance with respect to the size deviations in waveguide width, height and refractive index of the upper-cladding. Additionally, PSR devices based on Y-junctions with SiO2 upper-cladding, and SiN upper- and lower-claddings are designed for potential applications at shorter and longer wavelengths, respectively. These PSR devices could facilitate the development of silicon photonic devices in the mid-infrared.