Selective Etching Research Articles

Semiconducting Properties of Delaminated Titanium Nitride Ti4N3Tx MXene with Gate-Tunable Electrical Conductivity.

MXenes have garnered significant attention due to their atomically thin two-dimensional structure with metallic electronic properties. However, it has not yet been fully achieved to discover semiconducting MXenes to implement them into gate-tunable electronics such as field-effect transistors and phototransistors. Here, a semiconducting Ti4N3Tx MXene synthesized by using a modified oxygen-assisted molten salt etching method under ambient conditions, is reported. The oxygen-rich synthesis environment significantly enhances the etching reaction rate and selectivity of Al from a Ti4AlN3 MAX phase, resulting in well-delaminated and highly crystalline Ti4N3Tx MXene with minimal defects and high content of F and O, which led to its improved hydrophobicity and thermal stability. Notably, the synthesized Ti4N3Tx MXene exhibited p-type semiconducting characteristics, including gate-tunable electrical conductivity, with a current on-off ratio of 5 × 103 and a hole mobility of ∼0.008 cm2 V-1 s-1 at 243 K. The semiconducting property crucial for thin-film transistor applications is evidently associated with the surface terminations and the partial substitution of oxygen in the nitrogen lattice, as corroborated by density functional theory (DFT) calculations. Furthermore, the synthesized Ti4N3Tx exhibits strong light absorption characteristics and photocurrent generation. These findings highlight the delaminated Ti4N3Tx as an emerging two-dimensional semiconducting material for potential electronic and optoelectronic applications.

Nanoparticulated Vanadium Oxide on BiVO4 for Boosting Photoelectrochemical Glycerol Oxidation

Hydrogen (H2) has been spotlighted as ideal energy carrier due to its relatively higher energy density compared to fossil fuel and no carbon emissions during the energy generation. However, most of current produced H2 comes from as byproducts in fossil fuel reforming processes. To reduce dependence on fossil fuel in the H2 production process, photoelectrochemical (PEC) water splitting is considered as promising strategy for producing H2 using sustainable resources. Nevertheless, the insufficient efficiency in PEC water oxidation oxygen evolution reaction (OER) has limited overall PEC water splitting system efficiency due to its relatively high oxidation potential and sluggish catalytic kinetics. Furthermore, the low value of generated oxygen has been pointed out as obstacle from an economic perspective. To overcome these challenges, glycerol, byproduct of biodiesel, has been attracted numerous attentions as PEC oxidation resource since it has three hydroxyl groups and relatively lower oxidation potential than OER. Furthermore, glycerol oxygenated value-added products like dihydroxyacetone (DHA) can improve economics of PEC hydrogen production system. Upon these strengths, PEC glycerol oxidation reaction (GOR) provides improved strategy that generates value-added products in anodic part and green energy source (H2) in cathodic part simultaneously, which can replace PEC water splitting. Bismuth vanadate (BiVO4) is one of the most promising transition metal oxide based catalyst for PEC GOR due to its relatively narrow bandgap, high theoretical photocurrent density and deep positive valence band maximum (VBM) position. Additionally, although the surface kinetics of BiVO4 for OER has been sluggish, it potentially would be advantage for GOR with high production rate. However, the relatively instability of BiVO4 in acidic electrolyte during operation and lower selectivity of oxygenated products has hindered their practical application in PEC GOR. To solve these problems, introduction of nanoparticles as cocatalysts has been much studied for ameliorating surface kinetics and passivation the surface of photoanode. However, the interface between nanoparticles and photoanode with poor chemical interaction can induce the higher interfacial resistance and slow charge transfer efficiency rather. In this study, we present in-situ vanadium oxide (VOx) nanoparticle decoration on the surface of BiVO4 (VOx/BiVO4) via selective etching process using alkaline treatment for enhancing PEC GOR and we report the world best photocurrent density based on BiVO4 photoanode for GOR with high selective DHA production. VOx nanoparticles with an average size of 5 nm by selective etching process using alkaline treatment is decorated on the surface of BiVO4. The VOx promotes the surface reaction kinetics via modulating the fermi level and enhanced photovoltage of BiVO4 and improves long-term stability for GOR by compensation of V5+ and Bi3+, which combines both efficiency and stability. Furthermore, the surface decorated photoanode presents a 6.82 mA/cm2 (1.34-fold improvement) photocurrent density at 1.23 V versus the reversible hydrogen electrode (RHE) under 1 sun illumination, which has been attributed enhanced catalytic kinetics with upshifted fermi level and photovoltage of BiVO4. Moreover, the long-term stability of VOx/BiVO4 has been exhibited over 10 hours and the high selectivity for DHA is achieved. This study presents insight into the role vanadium of selective etched VOx on the surface of BiVO4 with low valence state than that of BiVO4 and improving the potential of BiVO4 based catalyst as GOR photoanode for high selective value-added DHA production using solar energy.

Hydrogen Evolution Atomic Cluster Catalysts-Decorated Hierarchical Nanoporous Zinc for on-Demand Hydrogen Generation By Metal Hydrolysis

In recent years, there has been an increasing interest in nanoporous metals due to their wide range of applications, including catalysis, electrocatalysis, energy storage, actuation, and plasmonics. However, considerable attention has been given to precious nanoporous metals such as nanoporous Au, Pd, Pt, Ag, and Cu due to their low chemical reactivity, which makes them relatively easy to synthesize and characterize. Less precious nanoporous metals such as nanoporous Zn, Al, and Mg have been rarely fabricated and characterized because of their relatively high chemical reactivity 1. In this talk, I will present a novel, highly scalable approach to making hierarchical nanoporous zinc (NP-Zn) decorated with atomic clusters of hydrogen evolution catalysts for on-demand hydrogen generation by metal hydrolysis. Our approach involves selective etching in combination with galvanic replacement reactions. The conventional selective etching method requires several days to create a monolithic piece of NP-Zn 2. Our approach creates the same amount of hierarchical NP-Zn in less than 5 minutes, instead of several days. In our work, we used focused ion beam/scanning electron microscopy techniques to reveal the internal nanoscale morphology of the hierarchical NP-Zn, and small-angle X-ray scattering to analyze the pore size distribution. In general, when NP-Zn is used for hydrogen generation by metal hydrolysis, the hydrogen generation yield is low, typically around 20%. This is because zinc is naturally a poor hydrogen evolution material. Our process overcomes this issue by creating NP-Zn with its interface decorated with clusters of hydrogen evolution catalysts, which enables hydrogen generation yield exceeding 90% depending on the catalyst loading. References (1) Fu, J.; Welborn, S. S.; Detsi, E. Dealloyed Air- and Water-Sensitive Nanoporous Metals and Metalloids for Emerging Energy Applications. ACS Appl. Energy Mater. 2022, 5 (6), 6516–6544. https://doi.org/10.1021/acsaem.2c00405.(2) Fu, J.; Deng, Z.; Lee, T.; Corsi, J. S.; Wang, Z.; Zhang, D.; Detsi, E. pH-Controlled Dealloying Route to Hierarchical Bulk Nanoporous Zn Derived from Metastable Alloy for Hydrogen Generation by Hydrolysis of Zn in Neutral Water. ACS Appl. Energy Mater. 2018, 1 (7), 3198–3205. https://doi.org/10.1021/acsaem.8b00419.

Cost-Effective Microfabricated Silver-Based Paper Cathodes for High-Discharge-Rate Aluminum-Air Batteries

We report a cost-effective microfabricated silver-based air-cathode for high-discharge-rate aluminum-air batteries which are suitable for micro-drone applications. A challenge for batteries for aerial drones is that both high gravimetric energy density and power density are required for extended operation. While air batteries can address the energy density issue, achieving high power density necessitates high loadings of expensive catalytic materials such as platinum (Pt), which can constitute over 99% of the cost in commercial air batteries. [1] Building upon prior research that studied the power performance of an aluminum-air battery (AAB) system with a silver-based cathode, this study further explores the influence of silver (Ag) sputtering conditions and Ag loadings on AAB power performance. [2]The power performance of AAB is significantly influenced by both air flux through the air cathode and electrochemically active catalyst surface area ratio (ECSA). The ECSA is the ratio of the electrochemically active catalyst surface area to its cathode area. Sputtered Ag cathodes with catalyst loadings ranging from 0.03 mg-Ag/cm2 to 0.3 mg-Ag/cm2 consistently show high porosity, indicating good air flux for the microfabricated cathode. Increasing the loading of the sputtered Ag catalyst further can lead to particle agglomeration. To improve power performance and ECSA, a silver-copper (AgCu) co-sputtering technique has been developed, significantly increasing the surface area and power performance.Figure 1 shows cathodes with Ag loadings ranging from 0.038 mg-Ag/cm2 to 0.267 mg-Ag/cm2 under two silver sputtering conditions: 400W+5mTorr and 100W+10mTorr. Within the examined range, the latter sputtering condition shows superior power performance compared to the former. For Ag loadings exceeding 0.1 mg-Ag/cm2, both conditions show decreasing power performance as Ag loading increases, and the 100W+10mTorr curve shows a maximum power at 0.088 mg-Ag/cm2. Figure 2 shows SEM images of 0.038 mg-Ag/cm2, 0.088 mg-Ag/cm2, and 0.19 mg-Ag/cm2 films, using the 100W+10mTorr sputtering condition. Ag particle size increases with higher Ag loading, which can result from particle agglomeration. Figure 3 shows the catalyst layer porosity and the ECSA calculated from the SEM images. All samples show porosity over 90%, indicating good air flux for the microfabricated Ag cathode. The trend of ECSA for different Ag loading correlates well with the power performance, suggesting that the power performance of the microfabricated Ag cathode primarily depends on the ECSA.Further enhancement of the ECSA through AgCu co-deposition is investigated, involving two parent alloy compositions (at%): Ag28Cu72 and Ag16Cu84. Following the co-sputtering, the parent alloy undergoes selective etching of Cu using hydrochloric acid (HCl). Figure 4 compares power performance between Ag28Cu72 and Ag16Cu84. Both curves exhibit an upward trend as the silver loading increases from 0.09 mg-Ag/cm2 to 0.4 mg-Ag/cm2, with Ag28Cu72 samples showing superior power performance. Figure 5 shows an SEM image of Ag28Cu72 parent alloy with 0.32 mg-Ag/cm2 loading after Cu etching, demonstrating that the ECSA increased to 47.52 while maintaining a high porosity of 90.2%. The peak power of Ag28Cu72 0.32 mg-Ag/cm2 sample is increased to 200 mW/cm2. By comparison, a 4mg-Pt/cm2 commercial cathode shows a peak power of 280 mW/cm2.Figure 6 compares the discharge performance of the 0.088 mg-Ag/cm2 cathode with a commercial 4 mg-Pt/cm2 cathode. Both cells can discharge under 1.1 Amp with a power density exceeding 500 W/kgbattery, a threshold sufficient to lift a quadrotor drone. [3] Battery weight encompasses anode, cathode, electrolyte and battery packaging. The 0.088 mg-Ag/cm2 cathode shows a discharge power plateau above 600 W/kgbattery (86% of the 4 mg-Pt/cm2) and an energy density of 228 Wh/kgbattery when discharge power density exceeding 500 W/kgbattery (95% of the 4 mg-Pt/cm2). Remarkably, the material cost of the 0.088 mg-Ag/cm2 cathode is 5000 times less than the 4 mg-Pt/cm2 cathode.

Enhancing Si1-XGex/Si Etch Rate Selectivity Using Etching Inhibitor in Radical Oxidation By Halide-Based Oxidant

As the technology node shrinks, innovation in the metal-oxide-semiconductor field-effect transistor (MOSFET) architecture has been required to mitigate the short-channel effects (SCE). Thus, planar FET had changed to FinFET and now gate-all-around FET (GAAFET) has been introduced with entering the 3-nm-generation. To fabricate GAAFET, selective etching of Si1-xGex- to Si-film is a key technology. According to the International Roadmap for Devices and Systems (IRDS™), the gate width of GAAFET is around 30 nm. Therefore, higher than 30 nm/min of etch rate for throughput and more than 400:1 of selectivity for acquiring a uniform Si-channel layer are required.As is well known, the etch rate in wet etching strongly depends on the standard reduction potential (SRP) of the oxidant. Our research group previously revealed the radical oxidation mechanism of sodium periodate (NaIO4) oxidant. In an acidic medium, NaIO4 can exist in periodate ion (IO4 -) form capable of generating hydroxyl radical (•OH). The high SRP value of hydroxyl radical (2.80 eV) compared to conventional oxidant, hydrogen peroxide (H2O2, 1.76 eV) and peracetic acid (PAA, 1.75 eV), resulted significantly high etch rate. In subsequent research, we introduced inhibitors reducing the Si-film etch rate to enhance Si1-xGex/Si etch rate selectivity when using sodium periodate as an oxidant.Acetic acid is commonly used as an additive in wet etchants to maintain uniform pH and control the etching of Si-film. However, it has several issues, strong vinegar odor, relatively large concentration to act, etc. Therefore, other additives are needed to substitute acetic acid. In selecting inhibitors, 2 factors are considered, i) scavenging effect for hydroxyl radical, and ii) hydrophobicity, as shown in Figure 1. Because the concentration of hydroxyl radical influences not only the Si1-xGex-film etch rate, but the Si-film etch rate, the scavenging effect of an inhibitor can reduce the film etch rate to enhance etch rate selectivity. Furthermore, the hydrophobicity part of inhibitors can build a hindrance layer on Si-film. Generally, Si-film has more hydrophobicity than Si1-xGex-film, inhibitors having hydrophobicity part are more prone to form a hindrance layer on Si-film than Si1-xGex-film. This results in the enhancement of Si1-xGex/Si etch rate selectivity by reducing Si-film considerably than Si1-xGex-film. The qualitative comparison of hydroxyl radical concentration depending on inhibitors and characterization methods to confirm the hindrance layer will be presented in detail. Acknowledgement This work was supported by the Technology Innovation Program (20022475, Development of wet Etchant capable of high selection etching in microprocesses below 10 nm) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea) References [1] Lee, Seung-Jae, et al. "Extremely high selective Si1−xGex-film wet etchant generating highly dissolved oxygen via peracetic acid oxidant for lateral gate-all-around FETs with a logic node of less than 3-nm." Chemical Engineering Journal 475 (2023): 146257. Figure 1

Selective Isotropic Dry Etching of SiO2 Using F/H-Based Pulsed Remote Plasma and a Vapor Phase Solvent

Isotropic etching generally employs liquid-based wet etching techniques. However, due to the high integration of devices, conformal etching is challenging in patterns with a high aspect ratio because liquid chemicals struggle to penetrate inside the pattern. Additionally, during the drying process after chemical treatment, pattern collapse is observed due to surface tension. Therefore, there is a need for dry isotropic etching techniques to replace wet etching techniques in next-generation device manufacturing processes.Typically, when high selectivity SiO2 isotropic dry etching is required, F-base/H-based gas mixtures are utilized to form HF, which serves as an etchant for SiO2. SiO2 can be dry etched through two different mechanisms. First, HF reacts directly with H2O or alcohol, etching SiO2. The other way is to produce (NH4)2SiF6 salt from the reaction of NH3, which can be formed in a plasma containing NH3 and NF3. This (NH4)2SiF6 salt is sublimated and removed by a following heating process at a temperature over 100ºC.The process above has some disadvantages, such as lowering the etch selectivity of SiO2 over Si and Si3N4 because Si and Si3N4 can be etched by F radicals remaining in the plasma. This study aimed to overcome these disadvantages by controlling the F radical through pulsing the remote plasma during the discharging of F-based/H-based gas mixtures for the formation of HF. By pulsing the remote plasma, SiO2 could be selectively etched at a higher etch rate relative to those of Si and Si3N4. Additionally, various types of H/F-based gas mixtures that do not contain nitrogen while producing HF were investigated to prevent the formation of ammonium powders, which can be a source of contamination in the chamber. Futhermore, the etching mechanisms were identified through gas phase anlysis and surface analysis. Also, any possible surface damage during the etching process was investigated.

High-performance GaN ultraviolet polarization-sensitive photodetector based on ferroelectric polarization LiNbO3

High responsivity ultraviolet (UV) photodetectors (PDs) are essential for abundant civilian and military applications. Gallium nitride (GaN) has emerged as an ideal material for UV PD fabrication due to its favorable properties. However, the quality of GaN epitaxial layers significantly impacts device performance and reliability. Sapphire-based GaN epitaxial growth technology enables the realization of high-quality GaN epitaxial layers, making it the preferred choice for GaN substrates. Nonetheless, the thermal expansion coefficient mismatch between sapphire and GaN can lead to crystal mismatch and stress accumulation at high temperatures, affecting device performance and reliability. In contrast, lithium niobate (LiNbO3) exhibits similar coefficients of thermal expansion to GaN, mitigating crystal mismatch and stress accumulation issues. Here, we report the realization of a GaN UV PD by laminating GaN membrane onto ferroelectric LiNbO3 through selective electrochemical etching of the sapphire-based GaN epitaxial film. The LiNbO3-based GaN PD achieves a specific high on/off ratio of 107. At a 5 V bias voltage, the device exhibits a high peak responsivity of 1.712 × 103 A/W under 325 nm laser illumination. Furthermore, the device demonstrates excellent performance for polarization light detection, with a polarization ratio of approximately 54.95. Exploiting the local ferroelectric polarization of x-cut LiNbO3, the photogenerated electron–hole pairs in GaN are efficiently separated by the electrostatic field from the polarization of ferroelectric LiNbO3, resulting in enhanced light-to-electric conversion efficiency. Our work presents a method for fabricating high responsivity GaN-based UV PD, showcasing the potential of integrating ferroelectric LiNbO3 to enhance device performance.

Influence of different viscosity and chemical composition of flowable composite resins: A 48-month split-mouth double-blind randomized clinical trial

ObjectivesTo evaluate the clinical performance of two flowable composites based on methacrylate and one based on ormocer in treating non-carious cervical lesions (NCCLs) after 48-month evaluation in a split-mouth double-blind clinical study design. MethodsA total of 183 restorations were performed on NCCLs using a universal adhesive system (Futurabond U, Voco GmbH) with selective enamel etching on 27 participants: two participants received twelve restorations each, three received nine restorations each, and 22 participants received six restorations each. Three different flowable composites were employed (n = 61): a low-viscosity methacrylate-based composite (GrandioSO Flow, LVM), a high-viscosity methacrylate-based composite (GrandioSO Heavy Flow, HVM), and an ormocer-based flowable composite (Admira Fusion Flow, ORM). All restorations were evaluated using FDI and USPHS criteria after 48 months. Statistical analysis was conducted using Kaplan-Meier Survival analysis and Kruskal-Wallis analysis of variance rank (α = 0.05). ResultsAfter 48 months, 17 restorations were lost: LVM 6, HVM 9, ORM 2. The retention rates (95 % confidence interval) were 89.4 % for LVM, 80.4 % for HVM, and 95.6 % for ORM, with a significant difference between HVM vs. LVM and HVM vs. ORM (p < 0.05). Minor defects were observed in 30 restorations for marginal staining criteria (LVM 12, HVM 10, ORM 8) and in 71 restorations for marginal adaptation criteria (LVM 24, HVM 20, ORM 27) without significant difference between groups (p > 0.05). No restorations showed postoperative sensitivity or recurrence of caries. SignificanceThe increased viscosity of flowable composites could reduce the clinical longevity in NCCLs after 48 months. Ormocer-based and low-viscosity methacrylate-based flowable composites showed a successful clinical performance in NCCLs after 48 months.

2D PtRhPb Mesoporous Nanosheets with Surface-Clean Active Sites for Complete Ethanol Oxidation Electrocatalysis.

The development of active and selective metal electrocatalysts for complete ethanol oxidation reaction (EOR) into desired C1 products is extremely promising for practical application of direct ethanol fuel cells. Despite some encouraging achievements, their activity and selectivity remain unsatisfactory. In this work, it is reported that 2D PtRhPb mesoporous nanosheets (MNSs) with anisotropic structure and surface-clean metal siteperform perfectly for complete EOR electrocatalysis in both three-electrode and two-electrode systems. Different to the traditional routes, a selective etching strategy is developed to produce surface-clean mesopores while retaining parent anisotropy quasi-single-crystalline structure without the mesopore-forming surfactants. This method also allows the general synthesis of surface-clean mesoporous metals with other compositions and structures. When being performed for alkaline EOR electrocatalysis, the best PtRhPb MNSs deliver remarkably high activity (7.8 A mg-1) and superior C1 product selectivity (70% of Faradaic efficiency), both of which are much better than reported electrocatalysts. High performance is assigned to multiple structural and compositional synergies that not only stabilized key OHads intermediate by surface-clean mesopores but also separated the chemisorption of two carbons in ethanol by adjacent Pt and Rh sites, which facilitate the oxidation cleavage of stable C─C bond for complete EOR electrocatalysis.

Fabrication of luminescent disc-shaped microstructures via wet-chemical etching of hybrid sol–gel layers for potential photonic applications

Sol–gel materials based on SiO2 and TiO2 precursors are attractive as a new platform for planar photonics. Particularly interesting are those based on organically modified silica (ORMOSIL), which may improve the luminescent properties of organic dyes. However, their microstructurization remains a challenge as it requires optimization of various technological stages. Here, we report the structurization of thin layers based on ORMOSIL precursor and titanium(IV) ethoxide (TET) containing luminescent rhodamine B (RhB) dye. Films were fabricated using sol–gel synthesis and dip-coating method. Depending on the time of annealing performed at 200 °C, layers with different thicknesses (300–760 nm) and refractive indices (RI) (1.51–1.68) were obtained. Combining photolithography and wet-chemical etching processes made it possible to fabricate well-separated sol–gel waveguides and discs of different diameters. The etching time in buffered hydrofluoric acid (BHF) affected the depth of the etched luminescent microstructures. Additionally, it was found that a longer layer’s annealing time increased the etching selectivity of the substrate over the sol–gel layer. This enabled the obtaining of under-etched sol–gel goblet microstructures. Selected samples were investigated using scanning electron microscopy (SEM). UV–Vis photoluminescence measurements showed that long heat treatment also influenced the emission spectrum’s shape. The stability of the films under ambient conditions was established using spectroscopic ellipsometry. It was proven that films heat-treated at 200 °C did not change their properties during storage time of around 2 months. Relatively high RI, luminescent properties, and structurization potential make these microstructures interesting for application in integrated photonic devices, e.g., light amplifiers or sensing systems.

Ultra-Long Carrier Lifetime of Spiral Perovskite Nanowires Realized through Cooperative Strategy of Selective Etching and Passivation.

Spiral inorganic perovskite nanowires (NWs) possess unique morphologies and properties that allow them highly attractive for applications in optoelectronic and catalytic fields. In popular solution-based synthesis methodology, however, challenges persist in simultaneously achieving precise and facile control over morphological twisting and fantastic carrier lifetimes. Here, a cooperative strategy of concurrently employing selective etching and ligand engineering is applied to facilitate the formation of spiral CsPbBr3 perovskite NWs with an ultralong carrier lifetime of ≈2 µs. Specifically, a novel amine of 1-(p-tolyl)ethanamine is introduced to functionalize as both a selective etchant and the source of forming an effective ligand to passivate the exposed facets, favoring the structural twisting and the enhancement of carrier lifetimes. The twisting behaviors are dependent on the etch ratios, which are essentially associated with the densities of grain boundaries and dislocations in the NWs. The ultralong carrier lifetime and long-term stability of the spiral NWs open up new possibilities for all-inorganic perovskites in optoelectronic and photocatalytic fields, while the cooperative synthesis strategy paves the way for exploring complex spiral structures with tunable morphology and functionality.

Unveiling the 3D Morphology of Epitaxial GaAs/AlGaAs Quantum Dots.

Strain-free GaAs/AlGaAs semiconductor quantum dots (QDs) grown by droplet etching and nanohole infilling (DENI) are highly promising candidates for the on-demand generation of indistinguishable and entangled photon sources. The spectroscopic fingerprint and quantum optical properties of QDs are significantly influenced by their morphology. The effects of nanohole geometry and infilled material on the exciton binding energies and fine structure splitting are well-understood. However, a comprehensive understanding of GaAs/AlGaAs QD morphology remains elusive. To address this, we employ high-resolution scanning transmission electron microscopy (STEM) and reverse engineering through selective chemical etching and atomic force microscopy (AFM). Cross-sectional STEM of uncapped QDs reveals an inverted conical nanohole with Al-rich sidewalls and defect-free interfaces. Subsequent selective chemical etching and AFM measurements further reveal asymmetries in element distribution. This study enhances the understanding of DENI QD morphology and provides a fundamental three-dimensional structural model for simulating and optimizing their optoelectronic properties.

The evolution of adhesive dentistry: a review of materials and techniques

Adhesive dentistry has undergone remarkable advancements since its inception, fundamentally transforming restorative dental care. Initially marked by the development of early resins and etching techniques, adhesive dentistry has evolved to incorporate sophisticated materials and innovative techniques that significantly enhance clinical outcomes. The introduction of Bis-GMA resins in the 1960s improved mechanical properties and reduced polymerization shrinkage, paving the way for modern composite resins. These composites, enhanced by nanotechnology and advanced filler technology, provide superior strength, wear resistance, and esthetic qualities. Techniques such as selective enamel etching and multi-layering of adhesive systems have further improved bond strength and reduced technique sensitivity. The clinical applications of adhesive dentistry are extensive, ranging from direct and indirect restorations to cosmetic procedures and preventive measures. Direct composite restorations offer minimally invasive solutions with excellent esthetics, while indirect restorations such as inlays, onlays, and veneers benefit from strong, reliable bonds and improved durability. Cosmetic procedures, including veneers, achieve dramatic esthetic improvements with long-lasting results. Preventive applications, such as sealants, effectively protect against caries, especially in pediatric and high-caries-risk patients. The continuous refinement of materials and techniques has led to better clinical outcomes, increased patient satisfaction, and reduced need for invasive procedures. Advances in adhesive materials and methods have ensured that restorations not only mimic natural tooth structures but also maintain their integrity under functional forces. As research and development in adhesive dentistry continue to progress, the field is poised to offer even more innovative and effective solutions, further enhancing the quality of dental care. Overall, the evolution of adhesive dentistry underscores its pivotal role in modern dental practice, providing durable, esthetic, and reliable restorative options that meet the diverse needs of patients.

Flexible, transparent, and durable slippery liquid‐infused porous surface achieved by void‐centered PVDF‐co‐HFP membrane for self‐cleaning antifog coating

AbstractBioinspired smart surfaces, such as slippery liquid‐infused porous surfaces (SLIPS), have garnered significant attention due to their efficacy in self‐cleaning, antifouling, and antibacterial applications. Despite their advantages, SLIPS exhibit limitations such as compromised transparency, insufficient stability, and limited slippery performance, which have hindered their widespread practical use. To address these challenges, this article proposes a rational design utilizing a void‐centered poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF) membrane for slippery liquid‐infused porous surfaces with exceptional flexibility, transparency, durability, and superior slippery performance. These advancements promise to enhance high‐performance, self‐cleaning, and antifogging coatings. The membranes, featuring large‐area, thickness‐customizable void‐centered PVDF, are fabricated through a two‐step process involving phase separation and selective etching. The utilization of PVDF polymer, which has a refractive index similar to that of silicon‐based lubricant oil, enhances transparency, while macrovoids positioned at the membrane's center, acting as oil reservoirs, improve the stability and performance of the SLIPS surfaces. Experimental findings demonstrate remarkable transparency of up to 93% in the visible light range and a lubricant oil uptake of 2.32 at a porosity of 70%. Moreover, the developed SLIPS exhibit outstanding durability, maintaining slippery performance with sliding angles of &lt;10° following exposure to either 400 consecutive droplets or aging for up to 40 days. This study significantly contributes to the development of future SLIPS, particularly for applications such as antifogging coatings on vehicle glass and solar panels, and self‐cleaning surfaces.

Effect of “fast”-crystallization and simultaneous glazing on physicochemical properties of lithium-disilicate CAD/CAM ceramic

ObjectiveEvaluate the impact of a “fast” crystallization and simultaneous-glazing on the physicochemical properties of lithium-disilicate CAD/CAM-ceramic. MethodsLithium-disilicate bars and crowns (IPS e.max CAD, Ivoclar-Vivadent) were divided into four groups (n = 30): WG/F (WG=with glaze/F=fast crystallization), NG/F (NG=no glaze), WG/C (C=conventional crystallization), and NG/C. A liquid/powder glaze system was used (IPS Ivocolor®, Ivoclar-Vivadent). Specimens were crystallized (Programat P310, Ivoclar-Vivadent) using the P161 program for C (approx. 20–25 min), and P165 for F (approx. 14–16 min). Bars (n = 30) underwent three-point bending tests (flexural strength-FS in MPa and modulus of elasticity-E in GPa) using a universal testing machine. Crowns were analyzed via scanning electron microscopy (SEM) after selective etching, and to Raman, FTIR-ATR, and X-ray diffraction (XRD) spectroscopies to assess chemical composition. ResultsFor FS, both factors/interaction were statistically significant. C (427.48±42.41 MPa) showed significantly higher values than F (409.82±38.82 MPa). WG (398.32±29.80 MPa) exhibited significantly lower FS than NG (438.21±41.77 MPa). For E data, both factors/interaction were significant. NG (90.28±14.71 GPa) displayed higher E than WG (83.07±5.69 GPa), while C (90.08±12.98 GPa) exhibited higher E than F (83.46±9.40 GPa). NG/C showed the best results for both variables. F groups showed (SEM) porous surfaces and crack-like marks on crystals. FTIR, Raman and XRD spectra confirmed the typical composition of a lithium-disilicate glass ceramic, and some attenuated signals and structural variations (XRD) in WG. Conclusions“Fast” crystallization and simultaneous-glazing produced weaker/less-rigid structures with irregular crystals and glassy phases. Simultaneous glazing may have hindered proper thermal distribution during crystallization. Significance“Fast” crystallization and simultaneous glazing with non-recommended systems, can adversely affect the final properties of lithium disilicate restorations.

Wide-range angle sensing based on mixed variable line spacing gratings

Variable line spacing (VLS) gratings are core components in spatial spectrum and synchrotron radiation facilities due to their merits of self-focusing, aberration correction, and flat focal field. However, optimal design and fabrication of VLS gratings are still required for matching various applications. Scratch-induced selective wet etching has been proven as a robust way for fabricating various nanostructures because of its simplicity, flexibility, and controllability. In this paper, we proposed convenient and maskless methods to fabricate VLS grating based on scratch-induced selective wet etching. During the etching, key factors, including normal load for the scratching, etching time, and types of etchants, were investigated systematically toward optimizing the process. The shapes including sidewall angle and the bottom curvature of the grating elements can be controlled by adjusting the normal load, etching time and/or etching etchants. It is found that the VLS gratings present a wide-range sensing for angle detection based on the reflection spectrum. Furthermore, combining transferring process, the VLS master gratings could be replicated on polydimethylsiloxane (PDMS) surface, which showed great optical performance. This work opened new light to some extent for the application of angle sensing and structural color showing.

Ultrasensitive electrochemical microRNA-21 detection based on MXene and ATRP photocatalytic strategy.

ATi3C2TxMXene-based biosensor has been developedand the photocatalytic atom transfer radical polymerization (photo ATRP) amplification strategy appliedto detect target miRNA-21 (tRNA). Initially, Ti3C2TxMXene nanosheets were synthesized from the Ti3AlC2 MAX precursor via selective aluminum etching. Then, functionalization of Ti3C2TxMXene nanosheets with 3-aminopropyl triethoxysilane (APTES) via silylation reactions to facilitate covalent bonding with hairpin DNA biomolecules specifically designed for tRNA detection. Upon binding with the tRNA, the hairpin DNA liberated the azide (N₃) group, initiating a click reaction to affix to the photo ATRP initiator. Through the ATRP photoreaction, facilitated by an organic photoredox catalyst and light, a significant amount of ferrocenyl methyl methacrylate (FMMA) monomer was immobilized on the electrode. Therefore, the electrochemical signal is amplified. The electrochemical efficacy of the biosensor was assessed using square wave voltammetry (SWV). Under optimized conditions, the biosensor demonstrated remarkable sensitivity in detecting tRNA, with a linear detection range from 0.01 fM to 10pM and a detection limit of 2.81 aM. The findings elucidate that thedeveloped biosensor, in conjunction with the photo ATRP strategy, offers reproducibility, stability, and increasedsensitivity, underscoring its potential applications within the experimental medical sector of the biomolecular industry.

Enlightenment of Deionized‐Water Bathing IGZO TFTs

AbstractAt present, amorphous indium–gallium–zinc oxide (IGZO) semiconductor has become the most commonly used semiconductor material and is widely used in flat panel displays and various sensors, but its performance is greatly affected by environmental factors, especially water. This study investigates the instability of IGZO thin‐film transistors (TFTs) soaked in deionized water. After 24 h bathing, the field‐effect mobility and threshold voltage change a little, but the subthreshold swing, positive bias stress and negative bias stress stability undergo clear degradation. Through comprehensive examination of the changes in the chemical composition, surface morphology and thickness of the IGZO films, it's found that IGZO experiences selective etching by deionized water, and consequently the film surface becomes rough and rich of In and oxygen vacancies, which can explain the variations on device performance well. In addition to the bathing experiment performed on In2O3, Ga2O3, and ZnO TFTs, a schematic image of the reaction between water and IGZO is depicted, showing the preferential loss of Ga and Zn located next to the oxygen vacancy.

Optimization of e-beam lithography parameters for nanofabrication of sub-50 nm gold nanowires and nanogaps based on a bilayer lift-off process

Electron beam lithography (EBL) stands out as a powerful direct-write tool offering nanometer-scale patterning capability and is especially useful in low-volume R&D prototyping when coupled with pattern transfer approaches like etching or lift-off. Among pattern transfer approaches, lift-off is preferred particularly in research settings, as it is cost-effective and safe and does not require tailored wet/dry etch chemistries, fume hoods, and/or complex dry etch tools; all-in-all offering convenient, ‘undercut-free’ pattern transfer rendering it useful, especially for metallic layers and unique alloys with unknown etchant compatibility or low etch selectivity. Despite the widespread use of the lift-off technique and optical/EBL for micron to even sub-micron scales, existing reports in the literature on nanofabrication of metallic structures with critical dimension in the 10–20 nm regime with lift-off-based EBL patterning are either scattered, incomplete, or vary significantly in terms of experimental conditions, which calls for systematic process optimization. To address this issue, beyond what can be found in a typical photoresist datasheet, this paper reports a comprehensive study to calibrate EBL patterning of sub-50 nm metallic nanostructures including gold nanowires and nanogaps based on a lift-off process using bilayer polymethyl-methacrylate as the resist stack. The governing parameters in EBL, including exposure dose, soft-bake temperature, development time, developer solution, substrate type, and proximity effect are experimentally studied through more than 200 EBL runs, and optimal process conditions are determined by field emission scanning electron microscope imaging of the fabricated nanostructures reaching as small as 11 nm feature size.

High-Energy–Density Fiber Supercapacitors Based on Transition Metal Oxide Nanoribbon Yarns for Comprehensive Wearable Electronics

AbstractFiber supercapacitors (FSs) based on transition metal oxides (TMOs) have garnered considerable attention as energy storage solutions for wearable electronics owing to their exceptional characteristics, including superior comfortability and low weights. These materials are known to exhibit high energy densities, high specific capacitances, and fast redox reactions. However, current fabrication methods for these structures primarily rely on chemical deposition, often resulting in undesirable material structures and necessitating the use of additives, which can degrade the electrochemical performance of such structures. Herein, physically deposited TMO nanoribbon yarns generated via delamination engineering of nanopatterned TMO/metal/TMO trilayer arrays are proposed as potential high-performance FSs. To prepare these arrays, the target materials were initially deposited using a nanoline mold, and subsequently, the nanoribbon was suspended through selective plasma etching to obtain the desired twisted yarn structures. Because of the direct formation of TMOs on Ni electrodes, a high energy/power density and excellent electrochemical stability were achieved in asymmetric FS devices incorporating CoNixOy nanoribbon yarns and graphene fibers. Furthermore, a triboelectric nanogenerator, pressure sensor, and flexible light-emitting diode were synergistically combined with the FS. The integration of wearable electronic components, encompassing energy harvesting, energy storage, and powering sensing/display devices, is promising for the development of future smart textiles. Graphical Abstract