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This study aimed at investigating the surface morphology and nanotopography of normal enamel (NE) and developmentally hypomineralised enamel (HE) when subjected to various pretreatment protocols under scanning electron microscopy (SEM) and atomic force microscopy (AFM). Sixteen NE, 16 creamy/white (CW) HE and 16 yellow/brown (YB) HE specimens sectioned from extracted hypomineralised first permanent molars (FPMs) were included in this study. They were randomly distributed into 12 experimental groups (n = 4). Each group involved the following: (1) deproteinisation with Papacarie Duo® gel or no deproteinisation, and (2) the use of Scotchbond™ Universal Adhesive (Scotchbond) in self-etch (SE) mode or 37% phosphoric acid etchant. Subsequently, the surface morphology and nanotopography of pretreated enamel specimens were evaluated under SEM and AFM, respectively. SEM observation showed that deproteinisation with Papacarie Duo® gel before phosphoric acid etching led to favourable etching patterns. This was consistent across all groups irrespective of the type of enamel specimen and the severity of hypomineralisation. In contrast, AFM results identified three factors that influenced surface parameters: (1) type of enamel specimen, (2) severity of hypomineralisation and (3) etching mode. YB HE recorded higher surface roughness values than CW HE and NE when subjected to the same pretreatment protocol. Deproteinisation and the application of Scotchbond in SE mode led to minimal topographic changes; however, acid etching was associated with an increase in surface roughness. Deproteinisation with Papacarie Duo® gel followed by acid etching contributed to improved etching patterns on HE.

Photocatalytic nitrogen fixation for the synthesis of ammonia is an important and attractive method to N2 turning into other compounds. The development of compact heterostructure photocatalysts is crucial for efficient solar energy conversion. Here, composite was obtained by simple in situ hydrothermal etching of the reduced TiO2 nanospheres with saturated calcium hydroxide solution. CaTiO3/TiO2 heterostructure composite can adsorb, activate and convert N2 to ammonia by using its close contact interface. Under simulated sunlight irradiation, CaTiO3/TiO2 composite greatly enhanced the photocatalytic N2 reduction performance. Compared with pure CaTiO3, the efficiency of 0.3-T–C heterostructure in synthesizing NH3 under visible light was 1.88 times higher than that of pure CaTiO3 (59.17 μmol·g−1·h−1) The excellent photocatalytic performance of CaTiO3/TiO2 is attributed to the close structure between CaTiO3 and TiO2, which promotes the separation of photogenerated charges and provides more active sites. This study provides a basic idea for the rational design of highly efficient heterogeneous photocatalysts to achieve excellent photocatalytic performance for N2 reduction.

In this study, the influence of primer contamination on enamel bonding was analyzed. Adper Scotchbond Multi-Purpose (SMP), CLEARFIL SE Bond 2 (SE2), Scotchbond Universal (SBU) Adhesive, and Scotchbond Etchant (35% phosphoric acid; PA) were used. Ground bovine enamels were divided into eight groups based on the bonding protocols. The bonding interfaces after an acid-base challenge were observed via scanning electron microscopy to determine the acid-base resistant zone (ABRZ). Moreover, the bonding interfaces after the nanoleakage challenge were analyzed via energy-dispersive X-ray spectroscopy. ABRZ was observed in all the samples except PA_ONLY (applied PA etching, No primer and No adhesive resin). The funnel-shaped erosion was detected only in X_SBU (applied SBU without PA etching). The nanoleakage test revealed silver patterns in some groups. The nanoleakage, i.e., the penetration of the silver ions, was detected in the groups wherein primer was applied on PA-pre-etched enamel.

Ferroferric oxide (Fe3O4)/C composites have received much attention as a result of converting electromagnetic waves to heat for harvesting efficient electromagnetic wave (EMW) absorbing performance. However, the practical EMW absorbing of these absorbers is still greatly hindered by the unmatched impedance properties and limited EMW absorbing ability. Tuning the morphologies at nanoscale and assembling the nanoarchitecture construction are essential to address this issue. Herein, dumbbell-like Fe3O4@N-doped carbon (NC)@2H/1T-MoS2 yolk-shell nanostructures are rationally designed and fabricated via a facile etching and wet chemical synthesis strategy. By manipulating the etching time toward the magnetic Fe3O4 component, the dielectric and magnetic loss of absorbers could be well-tuned, thus achieving the optimized impedance characteristics. As a result, the maximum refection losses (RLmaxs) of Fe3O4@NC-9h and Fe3O4@NC-15h are -19.8 dB@7.9 GHz and -39.5 dB@8.3 GHz, respectively. Moreover, the MoS2 nanosheets with a mixed 2H/1T phase anchored on Fe3O4@NC-15h (Fe3O4@NC-15h@MoS2) further boost the RLmax to -68.9 dB@5.8 GHz with an effective absorbing bandwidth of ∼5.25 GHz. The tailored synergistic effect between dielectric and magnetic loss and the introduced interfacial polarization (Fe3O4@NC/MoS2) are discussed to explain the drastically enhanced microwave absorbing ability. This work opens up new possibilities for effective manipulation of electromagnetic wave attenuation performance in magnetic-dielectric-type nanostructures.

High-resolution patterning with remarkable customizability has stimulated the invention of numerous scanning probe lithography (SPL) techniques. However, frequent tip damage, substrate-film deterioration, low throughput, and debris amassing in the patterned region are the inherent impediments that have precluded obtaining patterns with high repeatability using SPL. Hence, SPL still has not got wider acceptance for industrial fabrication and technological applications. Here, we introduce a novel SPL technique, named water electrolithography (W-ELG), for patterning at the microscale and potentially at the nanoscale also. The technique operates in the non-contact mode and is based on the selective etching, via an electrochemical process, of a metallic film (e.g., Cr) submerged into water. Here, the working of W-ELG is demonstrated by scribing a pattern into the Cr film by a traversing cathode tip along a preset locus. A numerical analysis establishing the working principles and optimization strategies of W-ELG is also presented. The tip-sample distance and tip-diameter are identified as the critical parameters controlling the pattern creation. W-ELG achieved a throughput of 1.5 × 107 μm2/h, which is the highest among the existing SPL techniques, while drawing 4 μm wide lines, and is also immune to deleterious issues of tip damage, debris amassment, etc. Therefore, the resolution of these inherent impediments of SPL in W-ELG sets the stage for a paradigm shift that may now translate the SPL from academic exploration to industrial fabrications.

The structural tailoring of pores is essential to high-performance Fe/N/C electrocatalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. Current strategies for pore structure engineering are usually accompanied with a drastic change of the intrinsic activity-related surface, which may mask the real effects of the porous structure on ORR activity. Herein, a mild carbon dioxide (CO2) etching method was used to flexibly tailor the pore structure of Fe/N/C electrocatalysts without drastic changes in their surface structure and property. In this way, via employing the Fe/N/C electrocatalysts as a model, the intrinsic impact of the pore structure on ORR activity was revealed. In addition, the CO2 etching method developed a high-quality electrocatalyst (sample Fe/N/C-5% CO2) with polarization performance exceeding that of the commercial Pt/C catalyst in the fuel cell working voltage region (>0.65 V). This work will promote the ongoing intensive studies on the rational design of the pore structures in the Fe/N/C electrocatalysts.

In this paper, the performance of SiC-based neutron detector was investigated using GEANT4 toolkit. Thin-film-coated and trench type neutron detectors were considered and their intrinsic detection efficiency were calculated according to the relevant structural parameters, with Low-Level Discriminator (LLD) value fixed at 300 keV. For thin-film-coated detector, the analysis carried out for varied layer thicknesses of 10B and 6LiF showed that the intrinsic detection efficiency increases with the increase of thickness, and reaches the maximum value at the critical thickness and thereafter found to gradually decrease. Due to the self-absorption effect of the conversion material, the intrinsic detection efficiency of the thin-film-coated SiC neutron detector is limited to less than 5%. Fortunately, the trench type SiC neutron detector can break through this limitation. However, under current process conditions, SiC can only be used for shallow trench etching. In order to increase the neutron detection efficiency as high as possible in the limited trench depth, we have proposed a scheme of filling the trench with a double conversion layer, which can significantly improve the intrinsic detection efficiency of neutrons compared with the traditional trench structure with a single conversion layer. Apart from estimating the intrinsic detection efficiency, the energy deposition spectrum in the SiC detector region by the produced secondary charged particles upon thermal neutron interaction with conversion material(10B and 6LiF) have also been researched for various structural parameters such as conversion layer thickness, trench width and trench gap of detector.

This paper presents a resonant differential-pressure (DP) microsensor with temperature (T) and static-pressure (SP) compensations. In this microsensor, three resonators were positioned on and beside the pressure-sensitive diaphragm and the corresponding intrinsic frequencies were translated into differential pressure under the interferences of temperature and static pressure. Finite element simulation was conducted for device modeling, locating the relationship between the intrinsic resonant frequencies of three resonators and values of differential pressure, temperature and static pressure. Microfabrication (e.g., photolithography, deep reactive-ion etching and anodic bonding) was employed to manufacture the microsensor with key fabrication results displayed in this study. Experimental characterizations were conducted, which indicated that the maximum fitting error of the fabricated microsensor was deceased from 2145.7 Pa (before compensation) to 98.2 Pa (after compensation) under a differential-pressure range from 0 kPa to 100 kPa, a temperature range from 10 °C to 60 °C and a static-pressure range from 110 kPa to 200 kPa.

We epitaxially grew bilayer molybdenum disulfide (MoS2) on monolayer graphene by sulfurizing a molybdenum-trioxide film (MoO3) which was deposited with thermal evaporation. The Hall mobilities of graphene before and after the growth of MoS2 are similar, indicating that the underlying 2D layer was little affected during the deposition and sulfurization. Through the atomic-layer etching, the topmost layer of MoS2 is isolated from the source and drain electrodes. The top-gate transistor with the isolated monolayer MoS2 on top of the graphene channel exhibits hysteresis of drain current as the gate voltage varies. This may be due to the weak tunneling through 2D layers bonded by the van der Waals force in the absence of an external electric field. The long retention time of the device features robust charge storage around the isolated MoS2 layer. The one-transistor-zero-capacitor memory module based on this thin heterostructure of 2D materials can be advantageous for applications in dynamic random access memories with reduced thickness.

Understanding the functions of biomolecules at the single-molecule level is crucial due to their important and diverse roles in cell regulation. Recently, nanotweezers made of dual carbon nanoelectrodes have been developed for single-cell biopsies by applying a high alternating voltage. However, high electric voltage can induce Joule heating, water electrolysis, and other side effects on cell activity, which may be unfavorable for cellular applications. Here, we report a low-voltage nanotweezer for trapping of single DNA molecules using etching-engineered nanoelectrodes which effectively reduce the minimum trapping voltage by six times. Meanwhile, the low-voltage nanotweezer displays an improved trapping stiffness. Based on the finite element method simulations, we attribute the mechanism for the low-voltage nanotweezers to the increase in spatial heterogeneity and nonuniformity of electric field by etching of quartz near the nanoelectrodes. This work opens a new dimension for noninvasive single-molecule manipulation in solution and potential applications in single-cell biopsies.

In this study, an Si nanowire (SiNW) array was prepared on a single-crystal Si wafer by a facile Ag-assisted wet-chemical etching route, followed by deposition of ultrathin Pt nanoparticles for enhancing the photoelectrochemical (PEC) performance. It was demonstrated that the PEC performance of SiNWs was enhanced significantly after Pt modification. A higher photocurrent density of − 12 mA cm−2 was achieved in Pt/SiNWs at − 0.845V versus a reversible hydrogen electrode, which was six times greater than that of bare SiNWs. The mechanism for the enhanced PEC performance was analyzed by combining the electrochemical impedance spectra and Mott–Schottky plots. As a result, the mechanism was attributed to the improved charge transfer ability at the solid electrode/electrolyte interfaces.

Chemical etching can create novel structures inaccessible by growth and provide complementary understanding on the growth mechanisms of complex nanostructures. Screw dislocation-driven growth influences the layer stackings of transition metal dichalcogenides (MX2) resulting in complex spiral morphologies. Herein, we experimentally and theoretically study the etching of screw dislocated WS2 and WSe2 nanostructures using H2O2 etchant. The kinetic Wulff constructions and Monte Carlo simulations establish the etching principles of single MX2 layers. Atomic force microscopy characterization reveals diverse etching morphology evolution behaviors around the dislocation cores and along the exterior edges, including triangular, hexagonal, or truncated hexagonal holes and smooth or rough edges. These behaviors are influenced by the edge orientations, layer stackings, and the strain of screw dislocations. Ab initio calculation and kinetic Monte Carlo simulations support the experimental observations and provide further mechanistic insights. This knowledge can help one to understand more complex structures created by screw dislocations through etching.

Core-shell structured hierarchical SSZ-13 microspheres with mesopore and zeolitic micropore were obtained via combining zeolite crystallization and post-synthesis fluoride etching. Secondary pores ...

Silver nanowire (AgNW) based transparent electrode (TE) plays a pivotal role in optoelectronics where TE is generally required to have fine pattern and high performance. Despite the rapid technological advances in either welding or patterning of AgNWs, there are few studies that combine the two processes in a simple and practical manner. Here, aiming to fabricate high-performance patterned AgNW TE, we develop a simplified photolithography that enables both plasmonic nanowelding with low-level UV exposure (20 mW/cm2) and high-resolution micropatterning without photoresist and etching process by conjugating AgNW with diphenyliodonium nitrate (DPIN) and UV-curable cellulose. The cellulose as a binder can effectively enhance plasmonic heating, adhesion, and stability, while the photosensitive DPIN, capable of modulating surface atom diffusion, can boost the plasmonic welding at AgNW junction and induce patterning in AgNW network with Plateau-Rayleigh instability. The fabricated AgNW TE has high figure of merit of up to 1, 000 (3.7 Ω/sq at 90% transmittance) and minimal pattern size down to 3 µm, along with superior robustness. Finally, a flexible smart window with high performance is demonstrated using the patterned and welded AgNW TEs, verifying the applicability of the simplified photolithography technique to optoelectronic devices.

Hydrogen peroxide (H2O2) plays a vital role in some of the metal assisted chemical etching (MACE) processes for silicon. However, it evaporates easily during etching at higher temperatures and this makes the process difficult to control. As a result, the MACE process for the inverted pyramid (IP) texturization that uses H2O2 is industrially unattractive. Herein, we proposed an innovative method to monitor H2O2 during the MACE process with an electrochemical method. The screen-printed electrode (SPE) modified by reduced graphene oxide (RGO) was used. The electrode demonstrated excellent electrochemical performance and could monitor the changes of H2O2 concentration with cyclic voltammetry (CV). Interestingly, the presence of copper (Cu) in the etching solution catalyzed not only the etching process, but also the electrochemical reduction of H2O2. With a consistent H2O2 concentration measured by the electrode, the reflectivity and structural morphology of the etched wafers could be controlled easily. The electrode is disposable, and the fabrication process is rapid and inexpensive, which is suitable for real time control of the MACE processes.

We investigated the suitability of aluminum nitride (AlN) for surface passivation and protection of gallium arsenide (GaAs), using a low-temperature passivation method. By varying the plasma power ...

The common polyol techniques were used for the synthesis of solo metallic morphology. Here we reported the single-step polyol-solvothermal strategy for the synthesis of zero, one, two, and three-dimension silver structure by simply switching the reaction pressure with the help of silver amount and halide ions. Silver seeds in the presence of Cl- ion, at 74.1 mmHg grow in [1 1 1] and at 97.4 mmHg grow in [1 1 0] direction for the formation of 0D-Ag and 1D-Ag respectively, by protecting (1 0 0) facet. Extra halide (Br-) presence at 93.2 mmHg imposes the seeds to grow [1 1 0], [1 0 0] direction for 2D-Ag, while at 97.4 mmHg grow only in [1 0 0] direction for 3D-Ag, due to etching and formation of single crystal seeds. This closed reaction system doesn’t need any kind of oxygen scavengers, inert gases, nor need to tune injection speed and stirring speed. This switching strategy can be implemented for the synthesis of other metallic morphologies.

In this work, we present a new fabrication methodology to enable high-performance thin-film transistor (TFT) with submicron channel length. The method can exceed the resolution limit of a conventional photolithography compatible with large-area substrates such as a glass or a plastic. The lift-off and back-channel etching techniques were employed to delineate the channel in the bottom-gate top-contact configuration. The Al-doped InZnSnO TFTs with $0.8~\mu \text{m}$ channel length were successfully fabricated. Field-effect mobility of over 50 cm2 /Vs, subthreshold swing of 90 mV/dec, on/off current ratio of > 1010, and turn-on voltage of −0.24 V were obtained. Considering the compatibility with the current manufacturing process and facility, we expect that the method can be incorporated in an easy and cost-effective way into the TFT array for high-performance large-area electronics.

As a typical correlated metal oxide, vanadium dioxide (VO2) shows specific metal-insulator transition (MIT) properties and demonstrates great potential applications in ultrafast optoelectronic switch, resistive memory, and neuromorphic devices. Effective control of the MIT process is essential for improving the device performance. In the current study, we have first proposed a photoassisted ion-doping method to modulate the phase transition of the VO2 layer based on the photovoltaic effect and electron-ion synergic doping in acid solution. Experimental results show that, for the prepared n-VO2/p-GaN nanojunction, this photoassisted strategy can effectively dope the n-VO2 layer by H+, Al3+, or Mg2+ ions under light radiation and trigger consecutive insulator-metal-insulator transitions. If combined with standard lithography or electron beam etching processes, selective doping with nanoscale size area can also be achieved. This photoassisted doping method not only shows a facile route for MIT modulation via a doping route under ambient conditions but also supplies some clues for photosensitive detection in the future.

Geometrical cues in the extracellular environment are essential for cells guiding. Conventional fabrications for well-defined microstructures are usually associated with expensive and time-consuming micro-electro-mechanical systems (MEMS), including lithography and etching. Additionally, the microstructures produced on silicon wafers are not amendable after molding, hindering the applicability. Here, we developed a low-cost and efficient fabrication process to generate highly ordered microstructures for cell culture by designing and fabricating a tunable wrinkled on biocompatible polydimethylsiloxane (PDMS) surfaces based on different mechanical properties of the biomaterials. The mechanical properties, including Young's modulus, tensile strength, and thickness ratio between the stiff and soft bilayers, can be determined by the thickness of PDMS film, curing temperature, UV exposure time, applied strain rates during the fabrication, leading to various amplitudes and wavelengths of the wrinkled topography on polymeric materials. Those wrinkled surfaces with micro-pattern are further applied to hCMEC/D cell culture, an immortalized human cerebral microvascular endothelial cell line, to induce cell proliferation and provide guidance for cell arrangement and migration. Therefore, this report sheds light on cell biology and biomedical tissue engineering by delivering an affordable and tunable fabrication process for wrinkles formations on the polymeric thin film.

This work explores the fabrication and characterization of an ionic liquid channel field effect transistor (FET) incorporated within the trench structure on SiO2. The trench structure allows any liquid to be accommodated, thereby eliminating the mold creation on the device or the requirement for an intricate architecture to store liquid. For the fabrication of the trench, we followed a standard photolithography process with the help of selective etching of aluminum and SiO2. The fabricated trench surface is characterized using atomic force microscopy (AFM) and contact angle analysis. The electrical characterization of the proposed FET structure is also performed with 0.01-mM potassium chloride (KCl) solution as an ionic channel. We tested both the n-FET and p-FET type characteristics which can be controlled by the back gate biasing condition. The dc characterization shows a high ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio of 105 for both the n-FET and p-FET. The device further shows an improvement in K+ mobility and Cl− mobility of $2.24 \times 10^{-4} {\mathrm {m}}^{2}/{\mathrm {Vs}}$ and $4.96 \times 10^{-4} {\mathrm {m}}^{2}/{\mathrm {Vs}}$ , respectively. We also carried out the FET structure modeling to estimate the effective ${C}_{{\mathrm {ox}}}$ for the trench SiO2 structure. It is observed that the total capacitance after the inclusion of Debye length is $1.29 \times 10^{-4} {\mathrm {F/m}}^{2}$ . Furthermore, the number of ions is also calculated from the electrical characteristics, and it is almost comparable with the number of ions in the molar solution. Overall, the proposed fabricated structure, although simple, enables to accommodate any liquid as a channel and provides an easy way to develop electrolyte-based sensors.

In this research work, a metallization strategy for the fabrication of core-shell polymer-metal composite filaments has been presented for the development of strain sensors. The polyamide filaments were etched by carefully controlling the etching parameters and observing the surface functionality which allowed metallization of the filaments. The Differential Scanning Calorimetry (DSC) analysis revealed that the etching treatment did not result in substantial loss in crystallinity. The Attenuated Total Reflectance – Fourier Transformation Infrared (ATR-FTIR) Spectroscopy showed intensification of amide peaks. This was accompanied by the preservation of methyl peaks indicating an absence of chain scission. Etching of the filaments was followed by surface activation and acceleration prior to plating. The metallization of etched filaments comprised of electroless plating followed by electroplating with copper which resulted in the formation of a porous spongy metal network on the substrate filaments as revealed by the morphological analysis carried out using optical and electronic microscopes. The spongy network of copper gave the sensors high sensitivity to strain due to the presence of metallic percolation network at low initial resistance. The metallized polyamide filaments with strain sensing ability showed bilinear behavior under monotonic static tensile loading with an initial gauge factor of 7.6 increasing to a value of just over 31 in the 2nd linear region. The hysteresis error also settled to a low value of ~0.01 after a few initial cycles during cyclic loading tests. The metallized polyamide filaments hold promise for structural health monitoring, proprioceptive testing, soft robotics and smart textiles etc.

Background This study aimed to assess the possibility of benzene exposure in workers of a Korean semiconductor manufacturing company by reviewing the issued patents. Methods A systematic patent search was conducted with the Google “Advanced Patent Search” engine using the keywords “semiconductor” and “benzene” combined with all of the words accessed on January 24, 2016. Results As a result of the search, we reviewed 75 patent documents filed by a Korean semiconductor manufacturing company from 1994 to 2010. From 22 patents, we found that benzene could have been used as one of the carbon sources in chemical vapor deposition (CVD) for capacitor; as diamond-like carbon for solar cell, graphene formation, or etching for transition metal thin film; and as a solvent for dielectric film, silicon oxide layer, nanomaterials, photoresist, rise for immersion lithography, electrophotography, and quantum dot ink. Conclusion Considering the date of patent filing, it is possible that workers in the CVD, immersion lithography, and graphene formation processes could be exposed to benzene from 1996 to 2010.

Color etching provides additional information that standard etchants do not or only insufficiently reveal – in different steels but also in virtually all non-ferrous metals. This works aims at presenting the possibilities this technology provides by using the examples of aluminum, copper, nickel, titanium materials, and cast iron, while also pointing out its limits.

Nanoindentations carried out by a "virtual plasma indenter" has been proposed in this study to solve the plasma etchings of Si wafer and determine the deep trench isolation (DTI) profile with a high accuracy. The methods of finding the virtual Gaussian-like indenter profiler and the back load applied to the back surface of indenter corresponding to the given etching conditions have been developed. The values of these two controlling factors in combination with the ANSYS/LS-DYNA software and the Johnson-Cook (J-C) fracture model allow us to solve the DTI profiles formed at various penetration depths. Good agreement between the experimental and simulational DTI profiles has been achieved and the efficiency and validity of the models developed for various etching conditions have been confirmed. From the analyses by the present models, the real dominant controlling factors for the geometries of DTI structure can be identified clearly, and the choices in the plasma etching conditions for the desired DTI geometries become easy and efficient. The present models can provide us an efficient way to determine the etching conditions required for the fabrication of a desired DTI structure with a high accuracy.

The enhanced surface area of silicon nanotexture is an important metric for solar cell integration as it affects multiple properties including optical reflectance, dopant diffusion, and surface recombination. Silicon nanotexture is typically characterized by its surface-area-to-projected-area ratio or enhanced area factor (EAF). However, traditional approaches for measuring EAF provide limited statistics, making correlation studies difficult. In this article, silicon's dominant ultraviolet reflectance peak, R(E2), which is very sensitive to surface etching, is applied to EAF spatial mapping. A clear decay correlation between R(E2) and EAF is shown for multiple textures created using reactive ion etching and metal catalyzed chemical etching. This correlation is applied to R(280 nm) reflectance mapping to yield accurate, high-resolution full-wafer EAF spatial mapping of silicon nanotextures. R(280 nm) mapping is also shown to be sensitive enough to correlate the impact of nanotexture spatial variation on post-diffusion sheet resistance. Finite-difference time-domain simulations of several nanoscale pyramid textures confirm a decay band for R(E2) versus EAF, consistent with our measurements. We suggest that R(E2) mapping may prove useful for other silicon nanotexture properties and applications where EAF is important.

High-efficiency Cu(In,Ga)Se2 (CIGSe) thin-film solar cells are typically fabricated by a multistage coevaporation process. The Cu-rich composition achieved during the second stage is known to favor the grain growth of the polycrystalline CIGSe film and has a beneficial effect on the solar cell performance. In this article, we analyze the effect of copper stoichiometry on the grain size of sputtered CIGSe absorbers and the efficiency of respective solar cells. CIGSe absorber layers were deposited on Mo-coated soda-lime glass substrates by pulsed hybrid reactive magnetron sputtering from Cu-poor and Cu-rich Cu-In-Ga targets and simultaneous Se evaporation. CIGSe films sputtered with the Cu-rich target show larger grain size and lead to better solar cell performance. Furthermore, we also introduce a two-stage process, which further increases the solar cell performance, consisting of an initial CIGSe layer deposited from the Cu-rich target followed by an indium-selenide postdeposition step. This two-stage process effectively eliminates the unwanted Cu2- x Se impurity phase and renders the otherwise required and toxic KCN etching unnecessary.

The kinetics of reactive ion etching of Si and SiO2 in the plasma of a high-frequency (13.56 MHz) inductive discharge in a CF4 + O2 mixture in the range of input power of 200–600 W (0.02–0.06 W/cm3) is studied. The key plasma-chemical processes that form stationary electrophysical parameters and composition of the gas phase are identified (a), and the flux densities of neutral and charged particles on the treated surface are determined (b) with the combined use of plasma diagnostics by Langmuir probes and 0-dimensional (global) plasma modeling. It is found that the dominant etching mechanism for both materials is an ion-stimulated chemical reaction proceeding in the kinetic mode and limited by the fluorine flux. It is shown that the decrease in the effective probability of interaction in Si/SiO2 + F systems with an increase in the input power and gas pressure may be due to heterogeneous processes with the participation of oxygen atoms.

Single crystal diamond particles were heated with liquid phase alkali metals (Li, Na, K) in an argon atmosphere. It was found that Li reacts with the diamond above 600 degrees C, Na makes the surface rougher on a nm scale at 800 degrees C, and K did not change the surface morphology. The etching speed by the reaction with Li is the fastest on the (001) surface. Photoluminescence of the NV- (negatively charged nitrogen vacancy) center decreased only after the annealing with K. DFT calculations explained the strong chemical interaction between Li and the diamond (001) surfaces, and upward band bending at the interfaces with Na and K. The behavior of the NV-center photoluminescence is consistent with the extent of band bending. (C) 2021 Elsevier Ltd. All rights reserved.

The state of the surface layer of polished silicon substrates and the effect of surface-cleaning procedures, such as washing in an ultrasonic bath, etching, and vacuum annealing, is studied. The X-ray reflectivity technique is used to determine the root-mean-square (rms) roughness, thickness, and density of the damaged surface layer. It is shown that the substrates have a damaged surface layer 1.5 nm thick, which is most pronounced after annealing at 350°С. Based on the etching procedures and subsequent vacuum annealing, an approach is proposed for cleaning the surface from contaminants, the damaged layer, and obtaining substrates with a root-mean-square roughness of σz = 0.42 nm. This approach can be used, in particular, for the deposition of thin organic films.

Using photo electrochemical etching technique (PEC), porous silicon (PS) layers were produced on n-type silicon (Si) wafers to generate porous silicon for n-type with an orientation of (111) The results of etching time were investigated at: (5,10,15 min). X-ray diffraction experiments revealed differences between the surface of the sample sheet and the synthesized porous silicon. The largest crystal size is (30 nm) and the lowest crystal size is (28.6 nm) The analysis of Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscope (FESEM) were used to research the morphology of porous silicon layer. As etching time increased, AFM findings showed that root mean square (RMS) of roughness and porous silicon grain size decreased and FESEM showed a homogeneous pattern and verified the formation of uniform porous silicon.

As an important component of the atmosphere, ammonia (NH3) plays a very important role in maintaining the balance of environment. However, it is also one of the most toxic gases that can cause damage to the human respiratory system and mucous membranes even at low concentrations. As such, development of highly sensitive and selective NH3 sensors is of high significance for environmental monitoring and health maintenance. Herein, we have synthesized Au@Ag@AgCl core-shell nanoparticles (NPs) by oxidative etching and precipitating Au@Ag core-shell NPs using FeCl3 and further used them as optical probes for the colorimetric detection of NH3. The sensing mechanism is based on the fact that the etching of NH3 on AgCl and Ag shell leads to the variations of ingredients and core-to-shell ratio of the Au@Ag@AgCl NPs, thereby inducing noticeable spectral and color changes. By replacing the outmost layer of Ag with AgCl, not only is the stability of the sensor against oxygen significantly enhanced, but also is the sensitivity of the method improved. The method exhibits good linear relationship for the detection of NH3 from 0 to 5000 μmol/L with the limit of detection of 6.4 μmol/L. This method was successfully applied to the detection of simulated air polluted by NH3, indicating its practical applicability for environmental monitoring. This method shows great potential for on-site NH3 detection particularly in remote area, where a simple, fast, low-cost, and easy-to-handle method is highly desirable.

For the highly efficient and versatile polishing of metals, isotropic etching polishing (IEP), which is based on the merging of isotropic etching holes, has been developed. In this study, the feasibility and mechanism of isotropic etching polishing of nickel-based superalloy Inconel 718 (IN718) and the polishing characteristics have been studied. The potentiodynamic experiments revealed similar trends of the cathodic, passive, second passivation, and transpassive regions in all the electrolytes, while the corrosion susceptibility of IN718 successively decreased with the increasing H2SO4 concentration in the electrolyte. The etching anisotropy of the IN718 precipitated with different phases can be experimentally transmuted to isotropic etching by modulating the electrolyte concentration and keeping electrolyte temperature equal or above the room temperature. Because of the positive correlation of the etching current with isotropic holes density and diameter, etching at higher currents is promoted for the rapid and proficient polishing. The surface evolution mechanism during IEP has been confirmed. The surface roughness initially increased due to the formation of etching holes, then decreased abruptly owing to the rapid merging of etching holes and finally achieved a smooth surface. The wet grounded surface of IN718 with a roughness of Sa 62.7 nm has been transformed into a mirror-like smooth surface with a roughness of Sa 0.86 nm within 300 s of IEP at optimized conditions and a high MRR of 2.73 mm3/min has been achieved.

We have experimentally demonstrated the mode-locked and Q-switched fibre lasers based on MXene Ti3C2Tx as a saturable absorber (SA). MXene Ti3C2Tx was obtained using selective etching and then embe...

In this study, we investigated the effects of etching temperature on the characteristics of the recessed-anode AlGaN/GaN Schottky barrier diodes (SBDs). Although recessed-anode AlGaN/GaN SBDs etched at room temperature (RT), 100°C, and 180°C exhibited similar turn-on voltage (Von) and reverse current (IR), the uniformity of the devices under turn-on voltage and reverse current was improved with an increase in etching temperature. The mean-square errors of Von for devices etched at RT, 100°C, and 180°C were 0.062, 0.022, and 0.012 V, respectively, and those of log (IR) were 0.38, 0.29, and 0.10, respectively. Meanwhile, the uniformity of the ideality factor and Schottky barrier height for the devices etched at higher temperatures were better than that of the devices etched at RT. This is because high temperature helps to repair the etching damage and also helps to volatilize etching remains.

The high-efficiency processing and the high geometrical precision requirements on the transparent hard-brittle optoelectrical materials are attractive to the modern industrial’s interest. Laser-induced related ablation/etching technology is proved to be effective processing for micro/nanofabrication of the transparent hard and brittle materials, due to its unique advantages of mechanical micro-machining with controllable thermal damage. There are some influencing factors like laser duration, target-to-substrate distance (work distance), target materials (absorption resolution), laser fluence, and circumstance (pressure, air, resolution) which were discussed in this review. The processing qualities in various methods were compared and described in this review. The new development of laser-induced related ablation/etching and related advanced technologies is introduced at the end of this review.

Purpose This study aims to focus on roughening N-face (backside) GaN substrate prior to GaN-on-GaN light-emitting diode (LED) growth as an attempt to improve the LED performance. Design/methodology/approach The N-face of GaN substrate was roughened by three different etchants; ammonium hydroxide (NH4OH), a mixture of NH4OH and H2O2 (NH4OH: H2O2) and potassium hydroxide (KOH). Hexagonal pyramids were successfully formed on the surface when the substrate was subjected to the etching in all cases. Findings Under 30 min of etching, the highest density of pyramids was obtained by NH4OH: H2O2 etching, which was 5 × 109 cm–2. The density by KOH and NH4OH etchings was 3.6 × 109 and 5 × 108 cm–2, respectively. At standard operation of current density at 20 A/cm2, the optical power and external quantum efficiency of the LED on the roughened GaN substrate by NH4OH: H2O2 were 12.3 mW and 22%, respectively, which are higher than its counterparts. Originality/value This study demonstrated NH4OH: H2O2 is a new etchant for roughening the N-face GaN substrate. The results showed that such etchant increased the density of the pyramids on the N-face GaN substrate, which subsequently resulted in higher optical power and external quantum efficiency to the LED as compared to KOH and NH4OH.

Drop-tube processing was used to solidify rapidly a congruently melting, single phase intermeallic Ni5Ge3. This process results in the production of powders with diameters that are between 850–53 μm. After etching that occurs at low cooling rates (850–150 μm diameter particles, 700–7800 K s–1), an isolated plate and lath microstructure in what is an otherwise featureless matrix constitutes the dominant solidification morphology. By contrast, when the cooling rates are higher (150–53 μm diameter particles, 7800–42 000 K s–1), it is isolated hexagonal crystallites within a featureless matrix, which constitute the dominant solidification morphology. The TEM analysis of selected area diffraction shows that plate and lath microstructures are variants of e-Ni5Ge3, which are partially ordered. By contrast, the isolated hexagonal crystallites are revealed to be disordered. However, the featureless matrix of both microstructures are the fully ordered variant of the same compound. The plate and lath has a very different EBSD and GOS signatures to the hexagonal crystallites structure. Histogram of the correlated grain orientation angle distribution across grain orientation in plate and lath microstructure sample from the 300–212 μm fraction showing predominance of low angle grain boundaries. However, grain orientation in isolated hexagonal crystallites from 150–106 μm revealing the distribution typical of random grain orientation.

The effective recognition of antioxidants is considered to have far-reaching significance in medical diagnosis. Here, an efficient visual sensing strategy is developed to identify multiple antioxid...