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A four-year follow-up of a novel silane heat treatment method for bonding lithium disilicate overlays to tooth structures without hydrofluoric acid etching of the ceramic surface is presented in this case report. Silane heat treatment modifies the silane layer and thus enhances resin ceramic bond strength without hydrofluoric acid etching. The standard ceramic preparation technique prior to bonding silicate ceramics to tooth structure is hydrofluoric acid etching and applying a silane coupling agent, followed by dental adhesive. In this case, the micromechanical roughening of the ceramic surface was performed by air abrasion with Al2O3. Silane heat treatment with constant 120°C airflow, applied for 60 sec, followed by dental adhesive application enhanced the resin-ceramic bond strength. After a four-year follow-up, the restorations’ clinical appearance could be defined as excellent/very good according to the FDI clinical criteria for the evaluation of direct and indirect restorations. This clinical result supports many in vitro studies regarding the resin-ceramic bond strength and durability obtained through postsilanization heat treatment.

In this work, we have observed change in different physical properties and glucose sensing capability of Chitosan-Silica nanoparticle composite membranes (CSNCM) with pore diameter variation. For a particular mixture percentage of chitosan and SiNp dust, successful fabrication of deformation free, free-standing membrane formation was possible. Silica nanoparticles of three different sizes (NP1 ~ 100 nm, NP2 ~ 300 nm & NP3 ~ 500 nm) were prepared to produce CSNCM of corresponding pore sizes (CM1, CM2 and CM3 respectively). Hot NaOH etching was performed to induce surface pore in CSNCM matrix by dissolving Silica nanoparticles from the top layer. We have found that pore distribution, surface morphology, optical properties and dielectric properties are very much dependent on pore size of the membranes. For glucose sensing characterization, we have focussed on multi-parametric optical sensitivity of the membranes in presence of glucose molecules and found that, though all three membranes show response in one or more parameters, only CM2 membranes hold the capability to perform as a multi-parametric sensor in our optical sensing arrangement.

High-quality, ultra-precise processing of surfaces is of high importance for high-tech industry and requires a good depth control of processing, a low roughness of the machined surface and as little as possible surface and subsurface damage but cannot be realized by laser ablation processes. Contrary, electron/ion beam, plasma processes and dry etching are utilized in microelectronics, optics and photonics. Here, we have demonstrated a laser-induced plasma (LIP) etching of single crystalline germanium by an optically pumped reactive plasma, resulting in high quality etching. A Ti:Sapphire laser (λ = 775 nm, EPulse/max. = 1 mJ, t = 150 fs, frep. = 1 kHz) has been used, after focusing with a 60 mm lens, for igniting a temporary plasma in a CF4/O2 gas at near atmospheric pressure. Typical etching rate of approximately ~ 100 nm / min and a surface roughness of less than 11 nm rms were found. The etching results were studied in dependence on laser pulse energy, etching time, and plasma – surface distance. The mechanism of the etching process is expected to be of chemical nature by the formation of volatile products from the chemical reaction of laser plasma activated species with the germanium surface. This proposed laser etching process can provide new processing capabilities of materials for ultra—high precision laser machining of semiconducting materials as can applied for infrared optics machining.

The mechanism/effect of surface etching and post-process of Kevlar Fiber (KF) by metal ions were investigated in detail by etching Kevlar-29 fiber with different solutions. After the post-process of heat or solvent treatment, surface morphology changes of etched fibers were further discussed. Etching mechanisms have been demonstrated according to the results of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction instrument, atomic force microscopy, and scanning electron microscopy. The results exhibited that the coarsening of KF surface was caused by stress cracking instead of chain degradation. Furthermore, the cracks produced by stress cracking will extend lengthwise along the fiber surface due to the breakdown of hydrogen bonds. In addition, it is shown that the stress concentration appears on the fiber surface. In all, the etching mechanism consists of two parts: stress cracking and crack propagation. The proposed etching mechanism is of great significance to further improve the fiber surface and enhance the bond with the resin.

Present study demonstrates the fiber-optic localized surface plasmon resonance (LSPR) based sensitive biosensor for detection of Shigella bacterial species. The proposed sensor is comprised of multi-core fiber (MCF) having seven cores arranged in a hexagonal shape and spliced with single-mode fiber (SMF) for efficient detection. An increase in evanescent waves (EWs) and coupling of modes between MCF cores was achieved by etching process in a controlled manner. The etching process also increases the refractive index sensitivity (RIS) of the proposed sensor. Further, coating with nanomaterials like gold nanoparticles (AuNPs) and molybdenum disulfide (MoS2) helps in the excitation of localized plasmons. Here, Shigella specific oligonucleotide probes are used as a recognition element. The results demonstrate that the proposed sensor can successfully and efficiently detect the Shigella bacterial species with high sensitivity. Shigella in the range of 10 – 100 CFU/mL (colony-forming unit/mL) can cause serious intestinal infection and therefore, its detection in this range is critical. The proposed sensor demonstrates a linearity range from 1 to 109 CFU/mL with a detection time of 5 min and a limit of detection (LoD) of 1.56 CFU/mL. The proposed sensing methodology can be a potential alternative to the commercially existing ones in the near future.

Study level/applicability This case can be used in the core course on entrepreneurship for Bachelor of Business Administration (BBA) and Master of Business Administration/Post Graduate Diploma in Management (MBA/PGDM) students. It will help them to understand the motivations and challenges of women entrepreneurs, strategies to manage challenges, interactive style of leadership and their contribution to the economic growth of the country. Subject area Entrepreneurship. Case overview Roopa Rani, co-founded a digital design company, DesignTheme Innoventics (DTI), with her husband Yoganand, in November 2007, on the first floor of their residence. Yoganand’s creativity and Roopa’s determination made them bootstrap, scale slow and steady. As a novice to the industry, the initial days posed many challenges. Roopa hired artists to be appointed as designers, which gave them a unique selling preposition. They progressed slowly from a team of 2 to 20, with a revenue of INR 0.3M per annum to INR 12M per annum. As the company grew, Roopa wanted Yoganand’s support in handling the responsibilities, and hence, converted DTI into a limited liability partnership in 2013 and the couple were directors. As the client base improved, the need for shifting to a bigger space became more evident. A calculative risk-taker, Roopa, was forced to move DTI to a bigger office space end 2017, with a rent of INR60,000 per month. Meanwhile, they became a team of 20, with revenue of INR12m. The shift from no rent to a rented space made DTI slip to break-even. However, after two years, they moved into a smaller space and it coincided with the COVID-19 outbreak. Although the backlog orders were processed during the first quarter of 2020–2021, the business for the next quarter was affected. Social distancing norms created a shift in the way of doing business, which was a boon for a designing company like DTI. Now, the task before this self-made woman entrepreneur was to formulate strategies to scale up the business. Expected learning outcomes After analysing the case, the students will be able to: i. Value the contribution of women entrepreneurs towards the economy. ii. Examine the motivational factors and challenges of women entrepreneurs. iii. Understand the importance of networking. iv. Appraise the socio-cultural factors in a patriarchal society and their impact on the work-life balance of a woman entrepreneur. v. Appreciate the interactive leadership style of women entrepreneurs. vi. Formulate strategies to scale up the business. Supplementary materials • Agarwal, S., & Lenka, U. (2015). Study on work-life balance of women entrepreneurs – review and research agenda. Industrial and Commercial Training, 47(7), 356–362. doi:10.1108/ict-01–2015-0006 • Amit, R., & Muller, E. (1995). “Push” And “Pull” Entrepreneurship. Journal of Small Business & Entrepreneurship, 12(4), 64–80. doi:10.1080/08276331.1995.10600505 • Buttner, E. H. (2001). Examining Female Entrepreneurs' Management Style: An Application of a Relational Frame. Journal of Business Ethics, 29(3), 253–269. doi:10.1023/a:1026460615436 • Carter, S.C. (1997). E. Holly Buttner and Dorothy P. Moore (1997), ‘Women’s Organisational Exodus to Entrepreneurship: Self-reported Motivations and Correlates with Success', Journal of Small Business Management, January, pp34-47. • Cohoon, J. McGrath and Wadhwa, Vivek and Mitchell, Lesa, Are Successful Women Entrepreneurs Different from Men? (May 11, 2010). Available at SSRN: https://ssrn.com/abstract = 1604653 or http://dx.doi.org/10.2139/ssrn.1604653 •Fletcher, J. (1998), Relational Practice: A Feminist Reconstruction of Work, Journal of Management Inquiry, 7(2), 163-186. • Kirkwood, J. (2009). Motivational factors in a push‐pull theory of entrepreneurship. Gender in Management: An International Journal, 24(5), 346–364. doi:10.1108/17542410910968805. • Malyadri, G., Dr. (2012). Role of women Entrepreneurs in the Economic Development of India. Paripex – Indian Journal of Research, 3(3), 104–105. doi: 10.15373/22501991/mar2014/36. Pal, N. (2016). Women Entrepreneurship in India: Important for Economic Growth. International Journal of Pure and Applied Researches, 4(1), 55–64. Pugazhendhi, D. P. (2019). Problems, Challenges and Development of Women Entrepreneurs. Emperor Journal of Economics and Social Science Research, 1(4), 48–53. doi:10.35338/ejessr.2019.1407. Shastri, S., Shastri, S., & Pareek, A. (2019). Motivations and challenges of women entrepreneurs. International Journal of Sociology and Social Policy, 39(5/6), 338–355. doi:10.1108/ijssp-09–2018-0146. Tende, S.B. (2016). The Impact of Women Entrepreneurs towards National Development: Selected Study on Taraba State. Information and Knowledge Management, 6, 30–43. Xheneti, M., Karki, S. T., & Madden, A. (2018). Negotiating business and family demands within a patriarchal society – the case of women entrepreneurs in the Nepalese context. Entrepreneurship & Regional Development, 31(3–4), 259–278. doi:10.1080/08985626.2018.1551792 Subject code CSS 3: Entrepreneurship.

This systematic review and meta-analysis aimed to evaluate the effect of Er:YAG laser etching on shear bond strength (SBS) of brackets bonded to the enamel and compare to the phosphoric acid (contr...

Premature bearing failures due to white etching cracks (WECs) occur when the rolling contact is subjected to a so-called additional load such as an electrical current flow through the bearing in ad...

In this paper, for the first time, we have investigated a Dielectric Engineered Schottky Barrier MOSFET (DE-SBMOS) for Biosensor applications. The DE SBMOS uses dielectric engineering and modulation approach to detect biomolecules. The DE SBMOS incorporated the high-k gate dielectric at the source side and low-k gate dielectric at the drain side. In addition, a nano gap cavity is created near the source region by etching the gate metal precisely. The presence of biomolecules in the cavity results in change in drive current of the device. The sensitivity of the proposed device is measured in terms of threshold voltage (VTH), ION current, IOFF current, Subthreshold Swing (SS), and IDS current. In later part, misalignment effect of cavity length with high-k dielectric material length examined and that result in three different modes i.e. Underlapped Biosensor (UBS), Aligned Biosensor (ABS), Overlapped Biosensor (OBS). Based on aforementioned modes, the proposed device shows the optimal choice for OBS mode.

The charging effect seriously limits the quality of the pattern transfer from a mask onto the etched material in the plasma etching. This work investigated the effect of the pulse phase lag (sometimes called phase lag for short) of the dual-frequency pulsing between the bias power (2 MHz) and the source power (60 MHz) on the charging issue on the surface of two adjacent and asymmetrically-shaped mask holes based on a reliable modeling framework. This work first verified that various phase lags (0 to 180°) can result in different distributions of the electric-field (E-field) and the net charge density on the mask surface. Then next shows that the mask profile presents an increased deformation as the phase lag increases. The effect of the fluorocarbon passivation generated during the source pulse off-time was involved in the simulation of the profile evolution. In addition, the number of ions passing through the opening of these two mask holes varying with the phase lag was also examined, which shows an increasing trend with decreased pulse phase lag. These conclusions shed new light on the approach to reduce the mask damage and improve the high aspect ratio etching.

Realizing precise control over the size and functionality of nanomaterials is a prerequisite to their diverse applications in the areas of biology, environment, energy, and other emerging nanotechnologies. Herein, we demonstrate a general template strategy capable of fabricating functional noble metallic nanorods and nanopeapods. The templates are hollow silica nanotubes (HSNTs) produced from unimolecular micelles of bottlebrush copolymers. The variation of chain length and chemical composition of bottlebrush copolymers achieved through the reversible-deactivation radical polymerization dictates the length (L), inner diameter (D), and thickness (h) of HSNTs. Using such HSNTs as nanoreactors enables the fabrication of noble metals such as Au, Ag, and Pt nanorods or nanopeapods with silica shells in a space-confined manner. While the thickness and the interior space of HSNTs regulate the diffusion and intake of metal ion precursors, the formation of nanorods or nanopeapods with different lengths and diameters is well controlled. Upon etching out the silica shell, the resulting metallic nanorods are readily functionalized with polymeric ligands for excellent dispersity in aqueous and/or organic media. This feasible and versatile strategy represents a great leap forward in the controlled synthesis of one-dimensional metallic nanomaterials and hopefully promotes understanding their structure-determined physiochemical properties and board applications in medicine and catalysis.

Ferroelectric random access memory cell (FeRAM) consists of one selection transistor with high switching performance and one memory transistor with large hysteresis. The simple fabrication method for the selection transistor with high mobility and the memory transistor with large hysteresis within one cell has been a challenge and not adequately explored. We demonstrated the selective etching of dielectric polymer buffer layer for the organic ferroelectric memory cell. The dielectric buffer layer of polymethylmethacrylate (PMMA) is formed on the ferroelectric gate insulator of poly(vinylidenefluoride-co-trifluoroethylene) [P(VDF-TrFE)] to enhance mobility of selection transistors. The UV ozone was partially treated on the PMMA/P(VDF-TrFE) bilayer which enables the top PMMA layer to be selectively etched due to the large process margin because the UV ozone etch rate of PMMA to P(VDF-TrFE) is more than 50 times. While the selection transistor with the PMMA buffer layer shows an enhanced mobility of 0.2 cm2 V−1 s−1, the memory transistor undergoing UV ozone etching process with post-annealing exhibits conventional ferroelectric memory properties such as large hysteresis and good memory retention characteristics. In our ferroelectric memory cell, the memory transistor is electrically isolated completely from the high negative bias in the bit-line during switching-off of the selection transistor. Our polymer selective etching for a ferroelectric memory cell is a useful technique in developing nonvolatile polymer FeRAM. In this work, we proposed a selective etching process to implement a selection transistor and a memory transistor in a ferroelectric memory cell. The difference of etch rates of P(VDF-TrFE) and PMMA by UV ozone (UVO) treatment was investigated, and the effect of the UVO etching and post-annealing on the surface morphology and ferroelectricity of PMMA/P(VDF-TrFE) bilayer were examined. While the OFET with the bilayer shows high on-off current ratio, the selective etched bilayer exhibits good ferroelectric retention characteristics. Finally, we implemented the ferroelectric memory cell without crosstalk between neighboring cells.

Non-traditional machining process is more used to manufacture geometrically complicated and an accurate parts for electronics, aerospace and automotive industries. Chemical machining process is one of non-traditional machining methods, it is as well named as chemical etching. The current research is aimed to study the influence of the machining time, machining temperature, etching solution concentration on the material removal rate and surface roughness of aluminum alloy by using mix of acid FeCl3. There are three of machining temperatures (25, 30 and 35 oC) with three machining times (4, 8, and 12min) and etching solution concentration (25%, 50%, and 75%) were used as machining conditions. These conditions are significant variables that have effect on finishing performance of chemically machined aluminum alloy. Machining time has the greatest effect among these variables. The time is the most important parameter for maximum Material Removal Rate (MRR), and the interaction between temperature and etchant concentration is the next important parameter for maximum MRR. The time is the greatest parameter for minimum Ra, the interaction between time and temperature is the next significant parameter for less Ra. http://dx.doi.org/10.30572/2018/kje/100104

To assess through a systematic review and meta-analysis of in vitro studies, the influence of the etching strategy (etch-and-rinse versus self-etch) of universal adhesive systems on bonding to primary teeth. A systematic search was carried out in PubMed, Web of Science and Scopus. In vitro studies that compared the bond strength of the etching strategies of universal adhesives to primary teeth were included. Pooled-effect estimates were derived from a random-effects model by comparing the standardized mean difference between the etching strategies (α

Ultraviolet detectors are widely used in space exploration, military affairs, and disinfection. To further improve the responsivity and response time, we propose and demonstrate AlN three-dimensional metal-semiconductor-metal (3D-MSM) and flip chip 3D-MSM (FC-3DMSM) ultraviolet detector here. The performance of devices with different etching depth and electrode spacing has been investigated using APSYS simulation. According to the simulation results, we fabricated $0.5~\mu \text{m}$ -etched 3D-MSM (3D-MSM- $0.5~\mu \text{m}$ ) and $1.3~\mu \text{m}$ -etched FC-3DMSM (FC-3DMSM- $1.3~\mu \text{m}$ ) devices. Response time is decreased by 29.3% and 13.8% for 3D-MSM- $0.5~\mu \text{m}$ and FC-3DMSM- $1.3~\mu \text{m}$ devices, and responsiveness exhibits a 20.5% and 46.6% improvement at 200nm, compared with traditional MSM device. This is due to varied internal electric field distribution of 3D-MSM and FC -3DMSM device configuration, which accelerates the collection of photo-generated carriers and improves the carrier collection efficiency. Our work should advance the development of nitrides ultraviolet detectors.

In this work, structure designs and the corresponding energy loss analysis are conducted to achieve the high-efficiency n-type rear-junction solar cells with polysilicon passivated contact. We focus on the front-side structure design of solar cells, considering that the primary efficiency loss of the conventional n-type polysilicon passivated contact cells with boron-diffusion emitter is from the front side. A well-designed rear-junction solar cell with front localized n-type and rear full-area p-type polysilicon passivated contacts is expected to overcome these problems. However, the efficiency of rear-junction solar cells is sensitive to the front-side electrode contact resistivity. To accurately assess the practically achievable efficiency that the current technology can reach, we develop a simple modified TLM with wet-chemical etching to measure the contact resistivity of the n-type polysilicon contact. This method does not require relatively expensive photolithography and reactive ion etching tools and is easy to be used. When the contact resistivity of the front-side localized n-type polysilicon contact reaches 0.002 Ω·cm2 with a saturation current density of ~10 fA/cm2 in the front-side un-diffused area, the efficiency of the rear-junction n-type solar cell is expected to be ~26%, showing its potential for application in mass-production of high-efficiency crystalline silicon solar cells.

We presented and demonstrated a new type of vertical nanowire (NW) and nanosheet (NS) field-effect transistors (FETs), named vertical sandwich gate-all-around FETs or VSAFETs, which were formed with the process compatible in the main stream industry. The VSAFETs with self-aligned high- ${k}$ metal gates (HKMGs) were fabricated with epitaxy of Si/SiGe/Si sandwich structure, an isotropic quasi-atomic-layer-etch (qALE) process, and gate replacement process. The gate-length of VSAFETs is mainly determined by the thickness of SiGe film grown by epitaxy. The NW diameter and NS thickness could be obtained by the isotropic qALE method, which can be used to the Si-selective etching of SiGe. As a result, p-type NS and NW VSAFETs with good device characteristics were fabricated. Device performance and the influence of silicide, Ge fraction, Si cap, and high thermal process were investigated; threshold voltage tuning and reliability were also discussed.

In this study, we develop a reactive force field (ReaxFF) for a Si/O/H/F system to perform etching simulations of SiO2 with an HF etchant. Quantum mechanical (QM) training sets from density functional theory calculations, which contain structures of reactant/product and energies with bond dissociation, valence angle distortions, and reactions between SiO2 clusters and SiO2 slab with HF gases, are used to optimize the ReaxFF parameters. Structures and energies calculated using the ReaxFF match well with the QM training sets. Using the optimized ReaxFF, we conduct molecular dynamics simulations of the etching process of SiO2 substrates with active HF molecules. The etching yield and number of reaction products with different incident energies of the HF etchant are investigated. These simulations show that the developed ReaxFF offers insights into the atomistic surface reaction of the SiO2 etching process.

In order to effectively utilize the photovoltaic properties of gallium arsenide, its surface/interface needs to be properly prepared. In the experiments described here we examined eight different paths of GaAs surface treatment (cleaning, etching, passivation) which resulted in different external quantum efficiency (EQE) values of the tested photovoltaic (PV) cells. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) examinations were conducted to obtain structural details of the devices. X-ray photoelectron spectroscopy (XPS) with depth profiling was used to examine interface structure and changes in the elemental content and chemical bonds. The photoluminescence (PL) properties and bandgap measurements of the deposited layers were also reported. The highest EQE value was obtained for the samples initially etched with a citric acid-based etchant and, in the last preparation step, either passivated with ammonium sulfide aqueous solution or treated with ammonium hydroxide solution with no final passivation. Subsequent I–V measurements, however, confirmed that from these samples, only the sulfur-passivated ones provided the highest current density. The tested devices were fabricated by using the ALD method.

Exfoliated and plicated g-C3N4 nanosheets (CNsF) were prepared through a thermal-chemical exfoliation in which the bulk g-C3N4 was obtained first under thermal exfoliation, and then was exposed to an acidic etching using hydrofluoric acid under hydrothermal condition. The acidic etching not only exfoliated g-C3N4 nanosheets by disrupting weak van der Waals forces between layers, which led to formation of a monolayer or a few layers of g-C3N4 nanosheets, but also made disordered defects on its surface and created plicated g-C3N4 nanosheets. Under visible-light illumination, the optimized sample (CNsF-6%) showed a hydrogen evolution rate of 54.13 μmol h−1g−1 (without co-catalyst) and a specific surface area of 121.4 m2 g−1, which were about 4.7 and 2.5 times, respectively, higher than pristine g-C3N4. It also showed remarkably enhanced photocatalytic performance in removing various organic pollutants. This remarkable improvement probably arises from the porous nanosheets and an increased number of active sites resulting from the CNsF, which subsequently enhanced the charge separation efficiency. This work provided an alternative way to obtain highly active g-C3N4 photocatalysts.

A simple method is proposed for the synthesis of noble metal M@YSiO₂ (M = Au, Pd, Ag) yolk–shell nanoparticles. The effects of synthesis conditions on the preparation of yolk–shell nanoparticles were discussed in detail. According to the different corrosion resistances between inorganic silica and organosilicone in a selective etching solution, yolk–shell nanoparticles with large cavity and thin shell were prepared using the same aqueous medium in a step-by-step synthesis process. Different from traditional methods, this method is facile and efficient because the main synthesis process is carried out in an aqueous phase. This extended method may benefit the synthesis and application of other nanomaterials with a similar yolk–shell structure.

In this article, a PZT/Epoxy 1-3 piezoelectric composite based on picosecond laser etching technology is developed for the fabrication of high-frequency ultrasonic transducer. The design, fabrication, theoretical analysis, and performance of the piezocomposite and transducer are presented and discussed. According to the test results, the area of the PZT pillar is $20.5\mu \text{m}\,\,\times 20.5\,\,\mu \text{m}$ , the average width of the kerf is $4.5~\mu \text{m}$ , and the thickness of the piezocomposite is $38~\mu \text{m}$ . The fabricated 1-3 piezocomposite has a resonant frequency of 46.5 MHz, a parallel resonant frequency of 65 MHz, and an electromechanical coupling coefficient of 0.73. According to the wires phantom imaging, its imaging resolution can reach $50~\mu \text{m}$ . This study shows that the proposed picosecond laser micromachining technique can be applied in the fabrication of high frequency 1-3 piezocomposite and transducer.

The hydrogen behavior in the amorphous In–Ga–Zn–O (a-IGZO) thin-film layer according to the device process with top gate structure was quantitatively investigated. The hydrogen quantities in the a-IGZO thin-film layer with gate insulator (w/GI) and after GI dry-etching were increased by $3.40\times 10^{20}$ and $2.50\times 10^{\vphantom {D^{a}}20}$ /cm3, respectively, in comparison with without GI (w/o GI). In addition, the calculated carrier concentration of the a-IGZO thin-film layer by band alignment increased by $1.60\times 10^{18}$ and $7.38\times 10^{17}/cm^{3}$ , respectively, compared with w/o GI. Due to the plasma effect, the hydrogen quantity and the calculated carrier concentration in the a-IGZO thin-film layer after GI dry-etching slightly decreased from w/GI by $0.90 \times 10^{20}$ and $8.62 \times 10^{17}$ /cm3, respectively. The increased hydrogen quantity in the a-IGZO thin-film layer can contribute to increase in carrier concentration by providing free electrons through the hydrogen reaction with oxygen ions or transition of hydrogen state. Here, we attempted to correlate the hydrogen effect to the increase of the carrier concentration through various physical analysis.

MICRO-LEDs ( n-LEDs) HAVE been engaged in the next-generation display technology and evolved for various applications from several electronics manufacturers and institutions. The area of n-LEDs (less than 10 # 10 nm2) is desired for the high pixelsper-inch (PPI) value of the microdisplay, but the sidewall effect from the etching process will drop the quantum efficiency

Chemical and thermal etching techniques are commonly used in ceramography to enhance microstructural features. While thermal etching works well for high purity ceramic systems, this technique may not be appropriate where glass is present. Porcelain and industrial alumina both contain a glass phase, typically 40−60 vol% and 4−30 vol%, respectively, and these glass chemistries are proposed to be similar. Chemical etching of porcelain is common, but the images published in the literature are frequently over-etched. When glass is present in the grain boundaries of alumina, thermal etching can cause the glass to disappear or to recrystallize, obscuring the microstructure. Because of this, it is proposed that both chemical and thermal etching are necessary to prepare an industrial alumina microstructure for grain size measurements. In addition, it was observed that chemical etching is sensitive to the residual stress in the glass phase, becoming more aggressive when there is residual tension in the glass.

The sensitive and rapid detection of blood glucose is very important for monitoring and managing diabetes. Herein, a fluorescent/magnetic bimodal sensing strategy is proposed for glucose detection using a multifunction-responsive nanocomposite (MoS2 QDs-MnO2 NS). MoS2 QDs act as fluorescent probes, and MnO2 nanosheets are used as both quenchers and recognizers in this sensing platform. In the presence of glucose-mediated enzyme product (H2O2), MnO2 nanosheet is etched, thus releasing MoS2 QDs and Mn2+ ions, which causes the significantly enhancement of fluorescent and magnetic signals. Furthermore, MoS2 QDs-MnO2 NS-based fluorescent test paper is constructed for H2O2 sensing with the naked eyes. Under optimal conditions, the dual linear ranges of 20−300 μmol/L and 40−250 μmol/L toward glucose detection are obtained for the fluorescent and magnetic mode, respectively. Furthermore, this bimodal assay exhibits good reproducibility and acceptable accuracy in glucose detection of clinical samples, demonstrating great versatility and flexibility of multifunctional probes in glucose detection.

We report on metal-assisted chemical etching (MaCE) of single crystalline p-Ge(1 0 0) substrates at an elevated temperature, using dilute H2O2 solution, for various etching times in the range of 30–1200 s. We carry out atomic force microscopic and scanning electron microscopic studies to investigate the temporal evolution of microstructures on Ge substrates. It is observed that at lower etching times rough surfaces evolve, whereas higher etching times lead to the formation of pyramidally textured surfaces. In order to understand the present observations numerical simulation studies, based on continuum theory of stress-induced morphological instability, are carried out. Further, in an attempt to demonstrate the tunable multifunctional properties of pyramidally textured-Ge surfaces, we study light trapping and cold cathode electron emission properties of the same as a function of etching time. Interestingly, the optical reflectance of pyramidally textured surfaces reduces systematically with increasing etching time and the one evolved under an etching time of 1200 s can go down to an unprecedented low value of 0.23% over a broad spectral range (600–3000 nm). In addition, the turn-on potential for cold cathode electron emission from the etched-Ge surfaces also reduces steadily with increasing etching time with the lowest one being 1.7 V µm−1 (with the field-enhancement factor of 15,171) for the highest etching time of 1200 s. These are by far the best known results for any chemically etched-Ge surface and offer tremendous potential to fabricate various Ge-based optoelectronic devices.

Metal microelectromechanical systems (MEMS) provide attractive properties such as high reflectivity and high conductivity. They are typically processed using an organic sacrificial layer that is removed by an oxygen ash. This enables low-temperature processing but presents other problems. For example, ashing is not applicable to metals that are susceptible to oxidation. However, if an inorganic sacrificial silicon dioxide is used, its removal commonly involves acids, exposure to which can be detrimental to metals. For example, metallic films are susceptible to hydrogen incorporation, resulting in large compressive stress. In recent work with structural tantalum and sacrificial silicon dioxide as a model system, we demonstrated that hydrogen injected during the release process can induce 1200 MPa compressive stress. This work explores AlN and Cu as alternative sacrificial materials in which release etching of structural Ta by AZ 400K developer and FeCl3 solution, respectively, is hydrogen free. Isotropic release etching is observed for Cu at room temperature and for AlN above 60 °C. In comparison with 1200 MPa, the uniaxial stress change after structure release is 80 MPa compressive with Cu and is unchanged after AlN sacrificial etch. [2021-0005]

Graphene field-effect transistors (GFETs) show high electron transfer rates, high charge-carrier mobility, low electrical noise levels and flexibility of surface functionalization, which are useful to realize the sensors for various applications. The key challenge is to develop the processes to fabricate a uniform array of GFETs devices. In this paper, single-layered graphene (SLG) was synthesized on copper (Cu) substrate using chemical vapor deposition (CVD) followed by its successful transfer over silicon (Si) substrate. To realize an array of graphene-based devices/ sensors, the process of oxygen plasma based clean etching of SLG was optimized. The Raman and Field Emission Scanning Electron Microscope (FESEM) characterizations ensure the complete etching of SLG in 240 s using 200 W, RF (13.56 MHz) power. Optimized SLG etching would help to fabricate an array of GFETs as a biochemical sensor platform.

Nanostructured tricontinuous block polymers allow for the preparation of single-component materials that combine multiple properties. We demonstrate the synthesis of a mesoporous material from the selective orthogonal etching of a microphase-separated tricontinuous block polymer precursor. Using the synthetic approach of polymerization-induced microphase separation (PIMS), divinylbenzene (DVB) is polymerized from a mixture of poly(isoprene) (PI) and poly(lactide) (PLA) macro-chain transfer agents. In the PIMS process in situ cross-linking by the DVB arrests structural coarsening, resulting in a disordered block polymer morphology that we posit exhibits three nonintersecting continuous domains. Selective etching of the PI domains by olefin cross metathesis and PLA domains by hydrolytic degradation produces a mesoporous polymer with two independent pore networks arising from the different etch mechanisms.

MXenes are a large class of materials that are chemically exfoliated from metal–aluminum–carbon (MAX) bulk crystals into low-dimensional sheets. While many MXenes have been theoretically predicted, the careful balance required in the exfoliation between breaking the inter-layer bonds without damaging the intra-layer bonds of the sheets has limited synthesis and experimental study. Here, we developed the synthesis of Cr2C from its parent Cr2AlC MAX phase and showed the etching is optimized using sodium fluoride and hydrogen chloride with a modified minimally intensive layer delamination (mMILD) method in a cold environment of 9 ℃. We further optimized the intercalation and delamination using sonication and washing methods. The resulting Cr2C crystal structure was characterized. These results open up Cr2C to experimental study, including of its predicted emergent magnetic properties, and develop guidelines for synthesizing new MXene materials.

This paper reports selective etching process of borosilicate glass by laser-induced deep etching (LIDE) for through glass via (TGV) applications. Picosecond laser is used to modify the glass substrate, and then, with the help of the laser-induced selective etching (LISE), the modified glass samples are etched by hydrofluoric acid (HF) solution to complete the manufacture of TGV in the present experiments. Here we experimentally study the micro mechanism of LISE on borosilicate glass. At the laser affected zone (LAZ), a series of nanovoids along the path of laser beam propagating are observed, which contribute to enhanced etchability of LAZ when the glass sample is immersed in HF solution. Further, the mechanism of the fabrication of TGV is investigated, and the effect of key factors, including laser pulses, the concentration of HF solution and the chemical composition of borosilicate glass on TGV profile are studied. When compared with laser pulses, the effect of concentration of HF solution and the chemical composition on TGV profile is more remarkable. Optimized results show that vertical vias (~ 90 $$^\circ$$ ) can be achieved on borosilicate glass.

Intermetallic coverage (IMC) is one of the critical wirebond output responses that is usually checked to ensure the ball to pad integrity. The success of wirebonding relies on the formation of an interfacial intermetallic growth of ball bond to ensure it can withstand reliability stresses. The challenging approach in IMC analysis detect as over-etching around IMC area that leads to inaccurate IMC data collection. To address the over-etching, we generate a new method which is backside polishing that results to a reliable IMC data collection and help reduced the cycle time of IMC data gathering.

A CR-39 based method was developed for measuring the ultra-trace alpha radio activities in aqueous samples having curie levels of γ/β-radio activities. The chemical etching method was optimized to reveal the alpha tracks in CR-39. This new chemical etching method involved the use of a phase transfer catalyst tetraethylammonium bromide which reduced the track revelation induction time without deteriorating the track-etch parameters. The alpha track-etch parameters such as bulk-etch rate, track-etch rate, induction time, and the critical angle of alpha track registration were measured at 60 and 70 °C, with and without using a phase transfer catalyst in the chemical etching for the comparison and optimization. The track registration efficiency of CR-39 in the solution medium was measured using the samples having known alpha activity of mixPu, and value obtained was found to be (4.42 ± 0.12) × 10−4 cm. The registration efficiency value thus obtained was corroborated with the expected efficiency expected from the calculated range of alpha particles in the solution. This CR-39 based method was employed to quantify the alpha activity, as low as 0.2 Bq mL−1, in the aqueous radiopharmaceutical samples having the curie levels of γ/β radio activities.

Hierarchically porous MOFs (HP-MOFs) present advantageous synergism of micro- and mesopore but challenging in synthetic control at molecular scale. Herein, we present the first example of reversible and controllable mesopore generation and renovation in a microporous MOF of HKUST-1 via synthetic manipulation at molecular scale. An ammonia-gas etching strategy is proposed to create mesopores in carboxylate-based microporous MOFs and thus produce HP-MOFs. Gas-phase etching ensures uniform mesopore formation inside the MOF crystals via plane-oriented cutting the carboxylate-metal bonds off without affecting the crystal size and morphology. The mesopore size is controlled by the etching temperature, while the mesopore volume could be tuned by adjusting etchant pressure. The generated mesopores could be renovated using MOF precursors solutions so that to achieve controllable mesopore generation/closure, and encapsulation of the adsorbed molecules. This work demonstrates a powerful protocol for precisely tailoring and tuning the properties of MOF materials at molecular scale.

In this study, Clitoria ternatea was used to provide a quantifiable method for pH measurement. The researchers proposed a new pH measurement method that involves the use of a KrF excimer laser to perform laser-assisted etching of the crown structure of long-period fiber gratings. Processing of the front surface of the optical fibers through grating resulted in periodically structured optical fibers with a sensor diameter of $55~\mu \text{m}$ and a period of $660~\mu \text{m}$ ; these structured optical fibers were encapsulated using glass slides. On the front surface of the optical fibers, functional group modification of the fiber surface was conducted and a nanogold coating was applied using the self-assembly method. Additionally, Clitoria ternatea was bonded to the surface of the optical fibers for the measurement of refractive index. In the pH sensing experiment, the average loss sensitivity detected by the sensors with no nanogold self-assembled coating was 0.0635 dB/pH. By contrast, the average resonant wavelength sensitivity of the sensors with a nanogold self-assembled coating under localized surface plasmon resonance was increased to 0.173 nm/pH. Compared with the sensors with no nanogold self-assembled coating, the sensors with this coating had a wavelength drift sensitivity enhanced by a factor of 37.

Front-illuminated GaN-based p-i-n ultraviolet (UV) avalanche photodiodes (APDs) were grown by metalorganic chemical vapor deposition on a free-standing GaN substrate. X-ray diffraction measurements confirm the high crystal quality of the grown structure. Atomic force microscopy measurements show well-developed atomic step-flow morphologies with sub-nanometer root-mean-square surface roughness for scan sizes of 1 × 1 $${\mu m}^{2}$$ and 5 × 5 $${\mu m}^{2}$$ . Mesa etching is one of the major challenges in the fabrication of these devices. Inductively coupled plasma mesa etching creates damage which leads to an increase of the dark current, premature device breakdown, and noise. Front-illuminated GaN-based UV APDs were fabricated using ion-implantation isolation to reduce the sidewall leakage current and improve reliability. The devices show a very low reverse-bias low leakage current density of below 10−10 A/cm2 up to − 35 V. A maximum multiplication gain of 1 × 106 under λ = 355 nm illumination was demonstrated (device limited to a current density of 10 A/cm2). The spectral responsivity of an 82-μm-diameter APD shows a peak responsivity of 1.05 A/W under UV illumination at λ = 375 nm at the avalanche-break-down voltage.

We report a wavelength-tunable high-repetition-rate passively Q-switched fluoride fiber laser around $3~\mu \text{m}$ by using Ti3C2Tx MXene as saturable absorber (SA). The Ti3C2Tx MXene was synthesized by selectively etching aluminum layers in Ti3AlC2. The modulation depth, non-saturation loss and saturation fluence of the SA at 2866 nm were measured to be 43.10%, 25.16%, and 0.50 mJ /cm2, respectively. By introducing the Ti3C2Tx SA into a Ho3+/Pr3+ -codoped fluoride fiber, stable Q-switched pulses with a continuously tuning range of 30.8 nm (2868.4 nm-2899.2 nm) were achieved. The repetition rate was as high as 215.3 kHz with an output power of 142 mW at the wavelength of 2879.0 nm. Such compact mid-infrared Q-switched laser source with a high repetition rate is of great importance in various applications such as medicine, high-resolution photoacoustic microscopy, and remote sensing. Our work indicates that the Ti3C2Tx MXene is a promising broadband light modulator for pulsed laser sources around $3~\mu \text{m}$ .

Particles and cells can be patterned and moved (i.e., manipulated) precisely using acoustically driven techniques. To date, application of acoustic particle manipulation has been limited to plain surfaces. There is much potential for applying acoustic manipulation techniques to surfaces with microfabricated structures for high-throughput sensing. But adding thin film structures could alter manipulation characteristics compared to a plain surface. Using a two-chip setup that allows the wave generating device to be reused, we study the feasibility of acoustofluidic micro-manipulation on a surface-micromachined silicon (SMS) chip. The SMS chip is a complex superstrate with generic thin-film structures fabricated by patterning and etching multiple layers of thin films, with properties meant to represent a broad range of microfabricated devices. We report notable alterations in the particle separation distances on the SMS chip compared to a bare silicon superstrate, which we attribute to a change in wave type through a comparison of different superstrates prepared. We demonstrate a high cell viability after acoustic manipulation of live cells on the SMS chip. The results herein demonstrate the possibility of integrating a suite of microfabricated sensors on a chip with acoustically driven manipulation capabilities for multiplexed sensing and analysis for bio-applications.

The introduction of mesoporosity into the microporous metal-organic frameworks (MOFs) is expected to expand their applications. Herein, we report a green and facile method to obtain hierarchically porous MOF structures by using an air-steam etching process. By virtue of the protonation reaction between the imidazole moiety and water vapor, the protonated imidazole related linkers leave the framework, resulting in the formation of mesopores in the zeolitic imidazolate frameworks (ZIFs), as exemplified by ZIF-8. Given the mild etching process, the materials’ structural integrity and crystallinity are well maintained. Remarkably, the proposed steam etching approach is generally applicable, which can be readily extended to other ZIFs, such as ZIF-14, ZIF-69, and ZIF-71, thus representing a powerful strategy to construct hierarchically porous MOF materials.

Continuous scaling of device dimension pushed Si channel to its physical limit, alternative high mobility channels such as (Si)Ge and (In)GaAs have been considered to replace Si to further enhance CMOS performance. In the meantime, ultrathin body (UTB) semiconductor-on-insulator is compulsory structure for improved gate control and immunity against short channel effects in the ultimately scaled high performance and low power dissipation CMOS. To realize stacked multi- channel semiconductor-on-insulator platform on current mainstream Si wafers, layer transfer technology [1-3] utilizing direct bonding and selective etching was developed to integrate (Si)Ge or (In)GaAs channels on Si, showing great potential for ultimate device structures with heterogeneous integration. Figure 1(a) is the process flow for integrating InGaAs channel onto SiGe-on-insulator (SGOI) structure utilizing layer transfer technology [4]. It started with bottom SGOI pMOSFET fabrication. The SGOI structure was realized by 2-step Ge condensation technique, resulting in Ge content of 70%. After high k metal gate process, self-aligned Ni-SiGe alloy was formed as S/D metal. Subsequently, SiO2 interlayer was deposited by CVD, followed by CMP planarization. Then, InGaAs grown on InP was directly bonded onto SiO2 and InP substrates were selectively etched away. Finally, the top InGaAsOI nMOSFET fabrication and metal interconnection completed the CMOS fabrication. Fig. 1(b) shows the cross-sectional TEM images of fabricated InGaAs/SiGe channel stacked CMOS. Well aligned top and bottom devices are seen without any distinct defects. Figures 2 is a schematic flow for fabricating Ge/Si double channel-on-insulator structure by low temperature hetero-layer bonding technology (LT-HBT). The technology starts with the preparation of donor wafers (Fig. 2(a)) for the top Ge channel layer and host wafers (Fig. 2(b)) for the bottom Si channel layer. For donor wafers, a 200-nm-thick Ge was epitaxially grown on SOI wafer by reduced pressure CVD. After CMP planarization, ALD SiO2 is deposited onto Ge. For host wafers, implantation and dopant activation were carried out, followed by chemical treatment for Si oxidation. After surface activation by room temperature chemical treatment (Fig. 2(c)), the direct wafer bonding of both SiO2 surface was performed at 200 °C in a press machine (Fig. 2(d)). Then, the Si substrate of the donor wafer was removed with deep RIE. At this time, the BOX layer of the donor wafer serves as an etch-stop layer. Subsequently, the BOX layer and thin Si layer of the donor wafer were removed selectively in HF and TMAH solution, respectively (Fig. 2(f)). To precise control the top Ge channel thickness, a series of low damage etching process was adapted to thin down Ge (Fig. 2(g)). The realized double channel structure is fully isolated with an insulating insertion layer,[5] which is very promising for realizing novel complementary FET (CFET) with minimum process steps. The cross-sectional TEM image of Ge/Si stacked channel of CFET after high k metal gate process is demonstrated in Fig. 2(h). Even more multiple stacks can be realized by using LT-HBT. A vertically stacked three-layer structure with 2 bottom Si layers and 1 top Ge layers is also demonstrated using SOI-based donor wafers in Fig. 3, indicating the highly integrated density channel structure is possible. The feasibility of layer transfer technology has been proved for multi-channel structure with high mobility channels for N2 node and beyond. Acknowledgement This work was supported by JST Japan-Taiwan Collaborative Research Program, Grant Number JPMJKB1902, Japan and the Ministry of Science and Technology under Grant Number MOST-109-2628-E-492-001-MY3, 109-2923-E-492-001-MY3, 107-2221-E-492-016-MY3. References [1] T. Maeda et al., Appl. Phys. Lett. 109, 262104 (2016). [2] W. H. Chang et al., Mater. Sci. Semicond. Process 70, 123 (2017). [3]W. H. Chang et al., IEEE Trans. Electron Device 64, 4615 (2017). [4] T. Irisawa et al., VLSI 146 (2014). [5] T. Z. Hong et al., IEDM (2020) Figure 1

Carbon materials are of fundamental importance in the fields of energy, electronics, and the environment. Using petroleum pitch has been proposed as a sustainable method to fabricate carbon fibers, yet the process requires further advancements due to an decrease in pores during post-treatment. Here we hypothesized that dissolving micro–nanobubbles of CO2 in a pretreatment should favor the pore growth of carbon fibers during activation. Results show that when a swarm of CO2 micro–nanobubbles is employed as the sacrificial catalyst, the samples display a specific surface of up to 792 m2 g−1. The high density of the CO2 dissociated products caused the sample to include 70.71% micropores, thereby producing a disordered etching texture. The chemical state of the elements revealed that there were no marked impurities. This study provides a new strategy for the development of highly porous materials, that may possibly stimulate more research on advanced performance adsorbents or electrode materials.

In LED semiconductor manufacturing, it is important to evaluate the wafer reflectance in order to validate the quality of wafers. In this work, a learning model based on ${K}$ -means clustering and neural networks is proposed to analyze the relationship between etching parameters and wafer reflectance under a complex etching environment. The implemented clustering algorithm is used to cluster historical data and reduce the effect caused by different processing environments. Then, for each obtained cluster, a neural network is developed to learn the relationship between etching parameters and wafer reflectance. Finally, a real case study from an LED semiconductor fab is conducted to show the application of the proposed method. Experiments show that the proposed method achieves much better performance in comparison with support vector machine for mapping the relationship between etching parameters and wafer reflectance. Also, by the proposed method, the average prediction accuracy of the wafer reflectance can be improved by up to 9.38%, and the mean square error is reduced by 21.64% compared with the methods without clustering.

Periodic V-grooves channels, upright, and inverted pyramids structures were texturized on monocrystalline silicon (c-Si) substrates using ammonium hydroxide (NH4OH) solution. This cheap and CMOS compatible etching solution aims at the integration of circuits with photovoltaic (PV) cells for monolithic purposes. To obtain these structures, lithographed silicon dioxide (SiO2) patterns were used to delimit the c-Si surface regions to be etched by the NH4OH solution. After the SiO2 removal, a scanning electron microscopy images of the surface of the samples showed that the NH4OH etch exposed the facets, outlined by the SiO2 patterns, creating periodic V-groove channels, inverted, and upright pyramids structures with depths of 5.9 ± 0.1, 5.7 ± 0.4, and height of 6.9 ± 0.1 μm, respectively. These ordered structures reduced a polished c-Si control sample reflectance by 57.6 ± 0.1%, 53.3 ± 0.1%, and 51.6 ± 0.1%, measured by a spectrophotometer with integrating sphere and having reflectance values of 16.5%, 18.2%, and 18.9%, respectively. These results indicate that the etched periodic structures using a cheap and CMOS compatible NH4OH solution, increases the c-Si light trapping, by reducing its reflectance for values lower than 20%, which could be used to increase the light absorption on PV cells.

The combination processes of metal-assisted chemical etching (AgNO3 + HF + H2O2) and rounding etching (HNO3 + HF + H2O) were used for the texturization of diamond wire sawn (DWS) multi-crystalline silicon (mc-Si) wafers. The evolution of texture structure on the DWS mc-Si wafers was investigated in detail. The chemically microsurface-sphericizing (CMS) textures, which were nearly smooth spherical structure with a size of approximately 2–3 μm, were fabricated successfully on the DWS mc-Si wafers with the combination processes. Compared with the conventional metal-assisted chemical etching (MACE) textures, the CMS textures were improved on surface recombination and the filling of electrode, thereby boosting the electrical performance of the solar cells and the cell-to-module (CTM) loss at the module end. These CMS textures resulted in an increase in the output power of the photovoltaic module by 0.047 W per cell. The fabrication of these CMS textures may be easily scaled up in the photovoltaic production line.

We report a method for synthesizing freestanding GdBa2Cu3O7-x thin films with high current carrying capacity. On the LaAlO3 substrate, an epitaxial water-soluble sacrificial layer of Sr3Al2O6 was grown by RF magnetron sputtering, and then a GdBa2Cu3O7-x film was deposited on the sacrificial layer. By etching the water-soluble sacrificial layer, we obtained a freestanding GdBa2Cu3O7-x film. The surface of the freestanding film is smooth and dense and its critical current density reaches 0.65 MA/cm2 at a temperature of 30 K and a zero magnetic field. The successful preparation of this freestanding GdBa2Cu3O7-x film with high critical current density makes the application of superconducting films more extensive and flexible.