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Surface-enhanced Raman spectroscopy (SERS) has been widely used in the analysis of analytes because of its unique fingerprint characteristics, high sensitivity, and fast detection response. MXene is widely used in SERS studies among the various substrates due to its ultra-high chemical stability, excellent conductivity, hydrophilicity, and low fabrication cost. This mini-review summarizes MXene's research in the SERS field from two aspects. We reviewed MXene materials used as SERS substrates alone and combined with noble metal particles primarily. Subsequently, we outlined representative applications of MXene-based SERS in biomedicine, food safety, and environmental monitoring. Moreover, we discussed the technical bottleneck and the prospect of future development in this field. [ABSTRACT FROM AUTHOR]

This article provides a proof of concept on how Surface-enhanced Raman Scattering (SERS) can be combined with microfluidics towards the development of an in situ chemical detection method. A microfluidic device prototype was designed, fabricated, and characterized to demonstrate the feasibility of microfluidics in achieving analyte transport from the sample introduction site to the detection site. Subsequently, the microfluidic setup was used for monitoring the adsorption kinetics of the molecule rhodamine 6G (R6G) onto a SERS-active substrate; an application, for which only scare information is available in the literature. Moreover, this work demonstrates how the actual concentration of adsorbed R6G (moles m-2) onto the SERS substrate can be quantified in real time. SERS-active substrates, such the ones used in this study, can be integrated in a microfluidic device for achieving reproducible monitoring of the adsorption kinetics of a molecule in a liquid sample, or for detecting and reporting the concentration of an unknown target molecule during a diagnostic assay. [ABSTRACT FROM AUTHOR]

Noble-metal-based surface-enhanced Raman spectroscopy (SERS) substrates can be employed as catalysts capable of generating hot electrons to drive chemical reactions of target molecules adsorbed on their surface. However, the localized surface plasmons excited from pure noble metals generally exhibit relatively low hot-electron utilization efficiency with the reactants owing to charge carrier recombination. This problem can be solved by integrating heterogeneous structures with the noble metal. Herein, we describe the fabrication of bifunctional SERS substrates by constructing Au@Ag, Au@Ag2S, and Au@SiO2 core-shell nanoparticles and evaluate the effects of the three heterostructures (Au cores encapsulated by shells composed of metal, semiconductor, or insulator) on the hot-electron transfer efficiency by in situ monitoring of the catalytic dimerization of p-nitrophenol to form p,p′-dimercaptoazobenzene under 632.8 nm laser illumination. The developed SERS strategy opens up new opportunities for exploring hot-electron-induced reactions as well as providing a useful reference for photocatalyst selection. [ABSTRACT FROM AUTHOR]

Graded composite fillers exhibit unique advantages in alleviating residual stress in ceramic/metal brazed joints. However, traditional methods for preparing graded composite fillers are often complex and may deplete their strengthening phases. In this study, cold spray additive manufacturing was employed to fabricate yttria-stabilized zirconia (YSZ)-Ti 25 Zr 25 Ni 25 Cu 25 -Ag graded composite coatings on Cu substrates to serve as fillers. The graded composite coatings and the resultant Ti 3 SiC 2 /Cu brazed joints were systematically characterized to elucidate the deposition mechanism of the coatings and its residual stress-relaxed mechanism. The bondings between particles in the coatings, based on their plastic deformation ability, were classified into noncrystalline weak bonds and homogeneous strong bonds. Both bondings facilitated the elemental interdiffusion between filler and Cu substrate during the heating process, which contributed to the formation of Ag-Cu eutectic. This significantly reduced the required brazing temperature and its induced residual stress. Furthermore, the solid phase transformation of graded-distributed YSZ within the brazing seam from tetragonal to monoclinic achieved a smooth thermal transition and releasing residual stress at the same time. Consequently, the shear strength of the brazed joint reached to the highest value of 110.23 ± 3.45 MPa, which was Much higher than the previously reported values. This study introduces a novel method for residual stress relaxation assisted with cold spray technology and broadens its application in the brazing field. [Display omitted] • The cold spray additive manufacturing achieved the fabrication of graded composite coatings filler successfully. • The bonding mechanism between the particles during the cold spray process depended on their plasticity. • The interdiffusion between graded composite coatings filler and substrate led to much lower brazing temperature. • The graded-distributed yttria stabilized zirconia caused the smooth transition of coefficients of thermal expansion. [ABSTRACT FROM AUTHOR]

Hot-water repellency is of great challenge on traditional superhydrophobic surfaces due to the condensation of tiny droplets within the cavities of surface textures, which builds liquid bridges to connect the substrate and hot water and thus destroys the surface water-repellence performance. For the unique structural features and scales, current approaches to fabricate surfaces with hot-water repellency are always complicated and modified by fluorocarbon. Here, we propose a facile and fluorine-free one-step vapor-deposition method for fabricating excellent hot-water-repellent surfaces, which at room temperature even repel water droplets of temperature up to 90 °C as well as other normal-temperature droplets with surface tension higher than 48.4 mN/m. We show that whether the unique hot-water repellency is achieved depends on a trade-off between the solid-liquid contact time and hot-vapor condensation time, which determines the probability of formation of liquid bridges between the substrate and hot-water. Moreover, the designed surfaces exhibit excellent self-cleaning performance in some specific situations, such as oil medium, hot water and condensation environments. We envision that this facile and fluorine-free strategy for fabricating excellent hot-water-repellent surfaces could be valuable in popularizing their practical applications. [ABSTRACT FROM AUTHOR]

Microscopic Fourier-transform infrared (FT-IR) spectra are measured for a Cu/low-k interconnect structure using polarized IR light for different widths of low-k spaces and Cu lines, and for different heights of Cu lines, on Si substrates. Although the widths of the Cu line and the low-k space are 70 nm each, considerably smaller than the wavelength of the IR light, the FT-IR spectra of the low-k film were obtained for the Cu/low-k interconnect structure. A suitable method was established for measuring the process-induced damage in a low-k film that was not detected by the TEM-EELS (Transmission Electron Microscope-Electron Energy-Loss Spectroscopy) using microscopic IR polarized light. Based on the IR results, it was presumed that the FT-IR spectra mainly reflect the structural changes in the sidewalls of the low-k films for Cu/low-k interconnect structures, and the mechanism of generating process-induced damage involves the generation of Si-OH groups in the low-k film when the Si-CH3 bonds break during the fabrication processes. The Si-OH groups attract moisture and the OH peak intensity increases. It was concluded that the increase in the OH groups in the low-k film is a sensitive indicator of low-k damage. We achieved the characterization of the process-induced damage that was not detected by the TEM-EELS and speculated that the proposed method is applicable to interconnects with line and space widths of 70 nm/70 nm and on shorter scales of leading edge devices. The location of process-induced damage and its mechanism for the Cu/low-k interconnect structure were revealed via the measurement method. [ABSTRACT FROM AUTHOR]

A rolling-based printing approach for transferring arrays of patterned micro- and nano-structures directly from rigid fabrication substrates onto flexible substrates is presented. Transfer-printing experiments show that the new process can achieve high-yield and high-fidelity transfer of silicon nanomembrane components with diverse architectures to polyethylene terephthalate substrates over chip-scale areas (>1 x 1 cm²) in <0.3 s. The underlying mechanics of the process are investigated through finite element simulations of the contact and transfer process. These mechanics models provide guidance for controlling the contact area and strain in the flexible substrate during transfer, both of which are key for achieving reproducible and controlled component transfer over large areas. [ABSTRACT FROM AUTHOR]

Carbon nanotube thin film transistors (CNT-TFTs) are promising candidates for future high performance and low cost macro-electronics. However, most of the reported CNT-TFTs are fabricated in small quantities on a relatively small size substrate. The yield of large scale fabrication and the performance uniformity of devices on large size substrates should be improved before the CNT-TFTs reach real products. In this paper, 25 200 devices, with various geometries (channel width and channel length), were fabricated on 4-in. size ridged and flexible substrates. Almost 100% device yield were obtained on a rigid substrate with high out-put current (>8 μA/μm), high on/off current ratio (>105), and high mobility (>30 cm²/V·s). More importantly, uniform performance in 4-in. area was achieved, and the fabrication process can be scaled up. The results give us more confidence for the real application of the CNT-TFT technology in the near future. [ABSTRACT FROM AUTHOR]

The Ni contact layer was deposited on semi-insulating 4H-SiC substrate by magnetron sputtering. The as-deposited samples were treated by rapid thermal annealing (RTA) and KrF excimer laser thermal annealing (LTA), respectively. The RTA annealed sample is rectifying while the LTA sample is Ohmic. The specific contact resistance (ρc) is 1.97 × 10-3 Ω·cm2, which was determined by the circular transmission line model. High resolution transmission electron microscopy morphologies and selected area electron diffraction patterns demonstrate that the 3C-SiC transition zone is formed in the near-interface region of the SiC after the as-deposited sample is treated by LTA, which is responsible for the Ohmic contact formation in the semi-insulating 4H-SiC. [ABSTRACT FROM AUTHOR]

Printing is a promising method for the large-scale, high-throughput, and low-cost fabrication of electronics. Specifically, the contact printing approach shows great potential for realizing high-performance electronics with aligned quasi-1D materials. Despite being known for more than a decade, reports on a precisely controlled system to carry out contact printing are rare and printed nanowires (NWs) suffer from issues such as location-to-location and batch-to-batch variations. To address this problem, we present here a novel design for a tailor-made contact printing system with highly accurate control of printing parameters (applied force: 0–6 N ± 0.3%, sliding velocity: 0–200 mm/s, sliding distance: 0–100 mm) to enable the uniform printing of nanowires (NWs) aligned along 93% of the large printed area (1 cm2). The system employs self-leveling platforms to achieve optimal alignment between substrates, whereas the fully automated process minimizes human-induced variation. The printing dynamics of the developed system are explored on both rigid and flexible substrates. The uniformity in printing is carefully examined by a series of scanning electron microscopy (SEM) images and by fabricating a 5 × 5 array of NW-based photodetectors. This work will pave the way for the future realization of highly uniform, large-area electronics based on printed NWs. [ABSTRACT FROM AUTHOR]

Aerogels are predominantly mesoporous, extremely lightweight, low density (∼ 0.003 g/cm3) and thermally insulating materials. Over the years, aerogels have gained increasing attention due to their extraordinary properties (light, heat, sound, electricity and force) and application potentials in varieties of fields. Several studies have been carried out regarding aerogel preparation and its applications in coatings on different substrates. In this review, an overview of aerogels preparation and their application progress in coatings of most common substrates is presented. Attention is paid to aerogel coatings of textiles, leather, and substrates other than leather and textiles for special functionalities that could address the application progress in coatings. This review will help to inspire scientists and engineers towards novel aerogel materials and technologies to boost the industrial fabrication of flexible advanced materials. [ABSTRACT FROM AUTHOR]

Wide-Band Gap (WBG) power devices have become a promising option for high-power applications due to the superior material properties over traditional Silicon. To not limit WBG devices' mother nature, a rugged and high-performance power device packaging solution is necessary. This study proposes a Double-Side Cooled (DSC) 1.2k V half-bridge power module having dual epoxy resin insulated metal substrate (eIMS) for solving convectional power module challenges and providing a costeffective solution. The thermal performance outperforms traditional Alumina (Al2O3) Direct Bonded Copper (DBC) DSC power module due to moderate thermal conductivity (10 W/mK) and thin (120 mm) epoxy resin composite dielectric working as the IMS insulation layer. This novel organic dielectric can withstand high voltage (5 kVAC @ 120 mm) and has a Glass Transition Temperature (Tg) of 300°C, which is suitable for high-power applications. In the thermal-mechanical modeling, the organic DSC power module can pass the thermal cycling test over 1,000 cycles by optimizing the mechanical properties of the encapsulant material. In conclusion, this article not only proposes a competitive organicbased power module but also a methodology of evaluation for thermal and mechanical performance. [ABSTRACT FROM AUTHOR]

In this paper, thin film AlGaInP LED chips with a 50 μm thick composite metal substrate (Copper-Invar-Copper; CIC) were obtained by the wet etching process. The pattern of the substrate was done by the backside of the AlGaInP LED/CIC. There was no delamination or cracking phenomenon of the LED epilayer which often occurs by laser or mechanical dicing. The chip area was 1140 μm × 1140 μm and the channel length was 360 μm. The structure of the CIC substrate was a sandwich structure and consisted of Cu as the top and bottom layers, with a thickness of 10 μm, respectively. The middle layer was Invar with a 30% to 70% ratio of Ni and Fe and a total thickness of 30 μm. The chip pattern was successfully obtained by the wet etching process. Concerning the device performance after etching, high-performance LED/CIC chips were obtained. They had a low leakage current, high output power and a low red shift phenomenon as operated at a high injected current. After the development and fabrication of the copper-based composite substrate for N-side up thin-film AlGaInP LED/CIC chips could be diced by wet etching. The superiority of wet etching process for the AlGaInP LED/CIC chips is over that of chips obtained by mechanical or laser dicing. [ABSTRACT FROM AUTHOR]

Quality factor enhancement for inductor and transformer has been achieved by the techniques such as fabricating the inductor and transformer on a glass substrate having high resistivity and by fabricating the inductor far away the silicon substrate and within this distance use of air, high-resistive silicon and silicon nitride as cavity. The simulation results are obtained by using the tool ASITIC (analysis and simulation of inductor and transformer for integrated circuits). Inductor is a key component in radio frequency (RF)-based devices and shows poor RF characteristics when it is formed on a Si substrate chip. It happens because of substrate-based RF losses and parasitics arised due to inter spiral tracks. Fabrication of inductor and transformer on a glass substrate results in a high quality factor as well as high self-resonance frequency which shows good prospects in various radio frequency integrated circuits applications. [ABSTRACT FROM AUTHOR]

A novel strategy was reported on the design and fabrication of functional photosensitive hybrid sols (FPHSs) by non-alcoholic emulsification in the presence of a TiO2 nanoparticle and photoinitiator via a sol-gel process using tetraethylorthosilicate, γ-methacryloxypropyltrimethoxysilane (MPS) and hydrophobic silane coupling agents as precursors. Smart cellulose substrates with alterable superhydrophobic–superhydrophilic conversion were fabricated using FPHS via the ultraviolet (UV) curing process. The liquid FPHS was photocured into solid gel during UV irradiation for 40 s with MPSs in FPHS, which was verified via Fourier transform infrared spectra. The cellulose substrates were modified with FPHSs, and the water contact angles of the modified cellulose substrates were more than 150°. The superhydrophobicity was improved by the gathering of hydrophobic chains and particle deposition of hybrid gel on the fiber surface. Nevertheless, the water contact angles of the modified cellulose substrates were receded with UV irradiation from 158° to 0° in 200 min, due to TiO2 photoinduction. The irradiated cellulose substrates were placed in the dark, and the water contact angles were recovered to about 130°, gradually. What is more, the reversible process can be repeated more than eight times. The modified cellulose substrate presented excellent washing fastness, even suffering 10 times washing processing. The mechanical properties, including breaking strength and elongation rate, were improved after the coating and UV curing process, which considerably remedied the defects of the heating curing process on the mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract Reduced graphene oxide (rGO) thin films were prepared by one-step electrostatic spray deposition (ESD) technique with a precursor solution of graphene oxide in mixed alcohol solvent. The deposited rGO films showed decreasing thicknesses ranging from approximately 340 nm–120 nm as substrate temperature increased from 150 °C to 275 °C. Raman spectroscopy indicated lowest intensity ratio of D to G band (I D /I G) of the rGO films at substrate temperature of 275 °C. Highest carbon per oxygen (C/O) ratio was also obtained at substrate temperature of 275 °C. The ESD technique was used for film deposition on an area of 5 × 5 cm2, while an acetone gas sensor based on single layer rGO film was fabricated by one-step ESD technique. Results indicated the possibility of controlling thickness components in the rGO film, and the capability of large-area production by this scalable ESD method. Highlights • The rGO thin film can be prepared by one-step electrostatic spray deposition technique. • The reduction of graphene oxide changed by substrate temperature heating. • Large-area reduced graphene oxide thin films can be prepared by our technique. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Monolayer diamond grinding tools are commonly made by electroplating or brazing. However, electroplated tools involve weak grain/matrix adhesion due to a lack of chemical bonds, and brazed diamonds often suffer thermal damage resulting from the high-temperature brazing process. This paper reports a new method to fabricate monolayer diamond grinding tools by chemical vapor deposition (CVD) technique. First, diamond powders at the range of 7–180 μm are chosen as seeds of the abrasive grains. The seeds are randomly distributed on SiC substrates by spraying the suspension containing the seeds toward the substrates in a spin coater machine, or orderly positioned on the substrates by a patterned mask. Then CVD diamond growth is conducted on both the substrates and the seeds simultaneously. As-grown diamond films on the substrates are regarded as bonding layers of the grinding tools, and the original seeds with irregular and crushed morphologies can grow into blocky cube-octahedral grains with smooth surfaces, which are supposed to have enhanced mechanical strength. Raman spectra demonstrate that as-grown diamonds on both the substrates and the seeds are of high quality and low levels of graphitization. Besides, relatively low residual stresses are detected in the diamond grains, because both the bonding layers and the grains are made of diamond. Grinding tests are conducted using as-fabricated CVD diamond grinding tools and electroplated/brazed diamond grinding tools as comparisons. The results suggest that the CVD diamond grinding tools possess the best wear resistance in terms of the fracture of the diamond grains. This is attributed to the epitaxial grain structure that restrains the crack propagations. In addition, the wear of the CVD diamond grains can generate tiny pyramidal crystalline tips and sharp edges, indicating the unique shelf-sharpness during the grinding. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlight • Epoxy resins act as an encapsulant can solve the stability problem of quantum dots. • Epoxy resins also solve the problem of non-uniform luminescence. • CsPbBr 3 QDs in five different substrates has different luminescence is greatly related to the sizes effect. Abstract To research optical properties of materials for light-emitting-diodes (LEDs) fabrication, CsPbBr 3 quantum dots (QDs) were dispersed in five different substrates to investigate their luminescence. The results show that CsPbBr 3 QDs embedded in glass matrices have superior stability, however, the QDs could not be evenly distributed in the matrices, which resulted in uneven luminescence of the glass. To solve this problem, epoxy resin was introduced as cladding material, which yielded a product that had good stability and consistency. CsPbBr 3 QDs embedded in epoxy resin show great potential for green fluorescent components in LED applications. [ABSTRACT FROM AUTHOR]

Abstract In this paper, an integrated component of the three-electrode planar switch and the exploding foil bridge was fabricated on the ceramic substrate by the magnetron sputtering process and wet etching process, which was beneficial to the miniaturization, low energy and integration of the explosion foil initiator system. We discussed the self-breakdown voltage of the three-electrode planar switch under different structural parameters and established the formula of self-breakdown voltage. By testing the discharge performance of the integrated component under a charging voltage of 1300 V~1500 V, we obtained a delay time of about 300 ns for the component, which is lower than the delay time when the spark gap switch is used. This result showed that the inductance of the entire circuit was lower than the inductance of the conventional circuit. We conducted a preliminary study on whether the integrated components are affected by changing of the working environment. Finally, based on this integrated component, we have used LTCC technology to produce a new highly integrated EFI system. Highlights • The integrated component we designed is suitable for exploding foil initiator system. • We discussed the SBV of the planar switch under different structural parameters and established the formula of SBV. • We have prepared a new highly integrated EFI system using LTCC technology based on the integrated components designed. [ABSTRACT FROM AUTHOR]

Abstract In this work, GaN-based vertically conducting near ultraviolet light-emitting diodes (LEDs) were grown on n-SiC substrates by metal-organic chemical vapor deposition. 10 pairs or 20 pairs of Si-doped n-Al 0.2 Ga 0.8 N/n-GaN distributed Bragg reflectors (DBRs) were used to improve the performance of the LEDs. The central reflected wavelength of the DBRs structures agreed well with the emission wavelength of the LEDs. A 389 nm near ultraviolet electroluminescence (EL) emission peak could be clearly observed in all the LED samples in our study. The EL intensity of LEDs was obviously enhanced because of the application of DBRs. Angle-dependent EL spectra were measured as well. For all the measurement angle region, the near ultraviolet EL emission intensity of the LEDs with DBRs were higher than that of the LED without DBRs. Highlights • Vertically conducting near ultraviolet LEDs were achieved. • The electrical conductive distributed Bragg reflectors were applied in LEDs. • The angle-dependent characteristics of the LEDs were studied. [ABSTRACT FROM AUTHOR]

Abstract This review discusses the recent developments of flexible chemiresistive gas sensors, focusing on the main materials and fabrication techniques. This article provides a detailed description of the substrates used in the flexible gas sensing industry. It also highlights the main challenges faced when integrating a sensing layer on paper, textile or polymeric substrates. A detailed study of the sensing materials in terms of structural properties and sensing mechanisms is presented. This study uses examples of gas sensors to explain the sensing mechanisms and to emphasize the functionalization effect on the sensing performance of a material. It also highlights the exceptions in polymers sensing behavior. Since flexible substrates can't sustain high temperatures, the main techniques used to fabricate flexible gas sensors are explained such as coating, printing, physical vapor deposition, in situ-growth, in situ-polymerization and chemical vapor deposition. The last technique, which requires high temperatures, is mostly used prior to transferring a sensing layer to a flexible substrate. At the end, the main challenges facing the flexible gas sensing technology are pointed out. [ABSTRACT FROM AUTHOR]

The MoS 2 /GO hybrid composite thin film is prepared by a facile solution mixing process. To reduce the composite film spin-coated on a SiO 2 (300 nm)/Si substrate, thermal annealing at 600 °C for 1 h in a N 2 atmosphere is used. The thermally reduced GO (rGO) composite film is subjected to line patterning through a soft lithographic patterning method, and the patterned MoS 2 /rGO composite thin film is re-transferred onto a PET film from the Si substrate. The patterned MoS 2 /rGO composite thin film has a thickness of about 10 nm and the transmittance of the patterned MoS 2 /rGO composite thin film on the PET substrate is 93%. The NO 2 gas sensor device is fabricated and its basic characteristics are systematically investigated. The patterned MoS 2 /rGO composite thin film gas sensor has a sensitivity at least four times higher than the pure rGO thin film gas sensor. In addition, the characteristics of the sensor device are also maintained at a bending radius of 14 mm. This transparent and flexible patterned MoS 2 /rGO composite thin film can be used as a highly sensitive gas sensor that will detect a concentration as low as 0.15 ppm of harmful gases such as NO 2 . [ABSTRACT FROM AUTHOR]

Abstract Zirconium dioxide (ZrO 2) thin films were deposited onto glass substrates, indium tin oxide (ITO) coated glass substrates and nickel oxide (NiO) / ITO / glass structures by reactive radio frequency (RF) magnetron sputtering using a zirconium target at room temperature. The deposition power was held at 75 W and the influence of deposition pressure and film thickness on the properties of the ZrO 2 films were investigated. Optical, electrochemical and electrochemical impedance spectroscopy measurements of the ZrO 2 films were performed and the electrochromic behavior of a half-cell structure of ZrO 2 / NiO / ITO / glass was investigated in a wide spectral range. The amount of inserted/extracted charges into/from each film during bleaching/coloring process were investigated in detail. The highest coloration efficiency (24.3 cm2/C) and optical modulation (42.8%) at a wavelength of 550 nm were found for a ZrO 2 / NiO / ITO / glass structure having a ZrO 2 film with a thickness of 100 nm, deposited at 4.00 Pa. Finally, a unique design of an all solid-state electrochromic device with a configuration of ITO / NiO / wet lithiated ZrO 2 / dry lithiated tungsten oxide (WO 3) / ITO / glass was fabricated. The optical modulation of the device was 53% at 550 nm for the applied potentials of ±3 V. Highlights • Optical and electrochromic (EC) behavior of ZrO 2 were studied. • The EC behavior of a half-cell structure of ZrO 2 /NiO/ITO/glass was investigated. • An uniquely designed all-solid-state EC device was fabricated. • The large optical modulation was found to be 53% with the applied voltages of ±3 V. • The ZrO 2 film was used as Li+ ion conducting layer in the EC device. [ABSTRACT FROM AUTHOR]

ZnO and Ni doped ZnO (NiZnO) thin films were fabricated on c-plane sapphire substrate using Pulsed Laser Deposition (PLD) Technique. The surface states of the deposited thin films were analyzed using X-Ray Photoelectron spectroscopy (XPS) technique. The Zn LMM Auger transitions during XPS were examined in detail to identify the doping induced structural transformations in ZnO films. Hall effect and UV-Visible spectroscopic measurements were carried out on the prepared samples to estimate the electronic and optical properties. The obtained results favor the utilization of NiZnO as active well layer and ZnO as barrier layer in NiZnO/ZnO based Quantum Well structure fabrication. [ABSTRACT FROM AUTHOR]

Abstract Nonlinear optical properties are investigated in new composite materials. The investigated samples have been (i) a glass substrate covered by mesostructured (SiO 2 or TiO 2) film filled with the dye Rhodamine 6G, and (ii) a hybrid liquid crystal (LC) cell made on such mesostructured film. The nonlinear optical coefficients have been defined by two different techniques: the degenerate two-wave mixing in the regime of Raman-Nath self-diffraction, and the Z -scan method. The nonlinear optical absorption in the hybrid LC cell is strengthening under continuous laser radiation. The hybrid LC cell is perspective for applications in optical limiting and light-control-light LC valves. Highlights • Fabricating stable mesostructured sol-gel films with intercalated dye molecules • New hybrid liquid crystal cell containing a mesoscopic silica film • Enhanced nonlinear-optical absorption in new hybrid liquid crystal cell [ABSTRACT FROM AUTHOR]

A vacuum-assisted deposition setup was developed in pilot scale to scale up and continuously deposit zeolite-Y (ZY) nanoparticles on 14-in wide nanoporous polyethersulfone (PES) substrate. The deposited substrate was used for composite membrane fabrication for carbon capture from flue gas. The effects of operating parameters, including ZY dispersion concentration, pressure differential, and web speed, on the ZY layer thickness and uniformity were studied. A ZY dispersion concentration of 0.08 wt%, a pressure differential of 3.7 in Hg, and a web speed of 3 ft/min were identified as the optimal operating conditions for depositing a thin and uniform ZY layer with a thickness of approximately 160 nm. A mathematical model with two adjustable parameters was derived from Darcy's law to correlate the operating parameters to the ZY layer thickness. After coating a polymeric amine-containing selective layer on the deposited substrate, the formed composite membrane showed a CO 2 permeance of 800 GPU with a CO 2 /N 2 selectivity over 150 at the typical flue gas temperature of 57 °C, which was superior to the performance of the membrane coated on the bare PES substrate. This improvement was due to the reduced selective layer penetration and effective diffusional length from the deposited substrate. [ABSTRACT FROM AUTHOR]

A novel two-step approach, electrochemical deposition in a cobalt sulfate solution followed by hydrothermal treatment in a nickel sulfate solution, is used to fabricate nanofibrous NiCo 2 O 4 on carbon fibers for binder-free supercapacitor electrodes. The obtained NiCo 2 O 4 consists of nanofibers and nanoflakes which are connected with each other to form open nanopores in the active material. The material exhibits excellent pseudocapacitive performance with a specific capacitance as high as 1807 F g -1  at a current density of 1 A g −1 and a rate capability of 75% at 40 A g −1 . The remarkable electrochemical properties are attributed to the porous structure created by the hydrothermal reaction between oxyhydroxide and Ni 2+ ions. Compared to the conventional method based on hydrothermal decomposition of cobalt and nickel nitrates, this approach is more environment-friendly, and when used for preparation of binder-free electrode, it is more effective in confining nanostructred NiCo 2 O 4 growth to a conductive substrate and ensuring good contact between the active material and the substrate. [ABSTRACT FROM AUTHOR]

Mixed ionic and electronic conducting (MIEC) perovskites demonstrate advantages over Ni-cermet as fuel electrode materials for solid oxide cells (SOCs). However, SOCs are primarily electrolyte-supported planar designs in literature when MIEC perovskite fuel electrodes are employed, which are relatively easy to fabricate but usually have high electrolyte ohmic resistance. Perovskite fuel electrode-supported designs are rarely studied particularly for microtubular SOCs. In this research, (La0.3Sr0.7)0.9Ti0.9Ni0.1O3-δ-Sm0.2Ce0.8O1.9 (LSTN-SDC) electrode-supported microtubular cell LSTN-SDC/YSZ/(La0.8Sr0.2)0.95MnO3-δ is fabricated and characterized. The LSTN-SDC microtubular substrate is prepared using an in-house built spinneret extrusion system in combination with modified phase inversion method, featuring radially well-aligned microchannels open at the inner surface. A thin YSZ electrolyte of ~15 μm and (La0.8Sr0.2)0.95MnO3-δ electrode of ~25 μm are then fabricated on the substrate, respectively. Upon reducing treatment, nickel is exsolved from LSTN grains and uniformly decorated onto grain surface as Ni nanoparticles, and therefore on inner surface of microchannels in the substrate. With CO/CO2 gas mixture as the fuel, the complicated electro-/chemical reactions are identified in the substrate electrode. The electrolysis process in combination with surface catalytic process of nanostructured electrode substrate leads to highly efficient CO production from CO2 with conversion efficiencies of well above 100%. The electrolysis also facilitates to regenerate surface catalytic functionality of nanostructured electrode substrate. The redox stability advantages of the cell are demonstrated in both alternative reduction (CO)/oxidation (air) atmospheric conditions and reversible operating mode. [ABSTRACT FROM AUTHOR]

The extensive usage of P91 steel in certain reactor components requires its precision fabrication by wire electrical discharge machining (WEDM). The WEDM cut surfaces consist of primarily re-melted and solidified layer (recast layer) of 2-8 µm. The recast layer is a result of fast removal of heat by unaffected metallic substrate and dielectric medium leading to rapid cooling. The WEDM surface is expected to affect the component performance in terms of its corrosion properties. The microstructural changes taking place due to EDM cutting of P91 steel bring about a drastic change in the electrochemical response of surface as compared to that for bulk P91 steel. The surface microstructure is shown to alter the passivation behavior and resistance to localized corrosion. Electrochemical polarization studies were done to evaluate passivation, pitting and intergranular corrosion (IGC) behavior and field emission gun—scanning electron microscopy was used for microstructural characterization of P91 steel surfaces. The passivation behavior for P91 steel WEDM cut surfaces was better than that for diamond polished surface. But pitting corrosion resistance decreased for the P91 steel WEDM surface which is a result of inhomogeneities in the microstructure of recast layer. The IGC resistance though increased due to the decreased grain size in the surface layer. [ABSTRACT FROM AUTHOR]

This paper reports the preparation of dense and substrate-free PZT thick films. Electrohydrodynamic jet deposition and sol infiltration were utilized to produce dense PZT thick film, then wet chemical etching was employed to successfully remove the silicon substrate. Subsequently, a pure PZT thick film having a thickness of 14 µm without substrate was produced. The piezoresponse force microscopy technique was used to examine the piezoelectric constant ( d 33, f ), it was found that the d 33 was increased from 71 pm V −1 to 140 pm V −1 , having a double increase. It was also observed that the remnant polarization ( P r ) and relative permittivity ( ε r ) of PZT film were distinctly improved after the removal of silicon substrate. The experimental result shows that the substrate clamping had great effects on the electrical properties of PZT films and its effect value was evaluated. In addition, the systematic theoretical analysis of the substrate clamping on film was deeply studied. The theoretical analysis agrees well with the experiment results, which can be used to estimate the effect value caused by the substrate clamping. [ABSTRACT FROM AUTHOR]

Glass is an ideal substrate material to enable 2.5D and 3D packaging of ICs at low cost and high performance. However, it is a brittle material and is prone to failures during fabrication and operation. Large coefficient of thermal expansion (CTE) mismatch between copper and glass leads to thermomechanical stresses that can lead to glass cracking and delamination from glass interfaces. This paper focuses on modeling and reliability characterization of copper-plated through-package-vias (TPV) in glass packages. Thermomechanical simulations were carried out to obtain design guidelines for reliable TPVs in glass. Test-vehicles with different glass thicknesses and copper TPV fabrication conditions were fabricated for thermal cycling tests, resistance monitoring and failure analysis. The reliability characterization results showed good thermomechanical reliability of TPVs in ultra-thin glass panels. [ABSTRACT FROM AUTHOR]

Graphene is widely recognized as a promising nanomaterial for the construction of high-performance electrochemical biosensors. However, the lack of strong interfacial forces between graphene and conductive substrates is a bottleneck in the fabrication of highly stable graphene electrodes. In this work, few-layer graphene was directly formed on a high pressure high temperature (HPHT) diamond substrate via sp 3 -to-sp 2 conversion by catalytic thermal treatment and using diamond itself as the carbon source. The hybrid electrode prototype was also highly conductive and had a linear electrochemical response to dopamine in the concentration range of 5 μM – 2 mM, with a low detection limit of 200 nM. After prolonged and repeated exposure to dopamine, electrode fouling was observed which led to sensitivity degradation. Based on the strong interfacial bonding between graphene and HPHT diamond, regeneration of the fouled electrode and full performance recovery would be easily achieved by ultrasonic cleaning. The hybrid electrode is highly robust, and shows potential in its application to the detection of biofouling molecules, food processing and wastewater treatment. [ABSTRACT FROM AUTHOR]

Bicrystal substrates, in which (100) planes in both single-crystal parts are rotated with respect to the surface by different angles around the [100] and [110] directions (parallel simultaneously to both the surface and bicrystal boundary), have been fabricated by solid-phase intergrowth on SrTiO3 crystals. Epitaxial bicrystal YBa2Cu3O7 films with different tilt angles of CuO planes to the surface have been grown on these bicrystals by pulsed laser deposition. The structure of these films has been investigated by X-ray diffraction. The films are shown to remain epitaxial when the film lattice is rotated from the position in which its (001) plane is oriented parallel to the surface by angles of up to 41° and 49° around the [100] and [110] axes, respectively. The possibility of growing bicrystal films of YBa2Cu3O7 high-temperature superconductor (HTSC), in which the CuO planes at different sides of the bicrystal boundary make different angles (up to 90°, which is the maximum possible angle from the symmetry point of view), has been demonstrated based on these data. [ABSTRACT FROM AUTHOR]

A simple method of applying and distributing multi-walled carbon nanotubes (MWCNTs) onto grit-blasted steel substrates has been investigated in this study to overcome the difficulty of mixing MWCNTs in epoxy adhesives forming the MWCNT-reinforced adhesive joints. MWCNTs were dispersed in an acetone and resin (no hardener) solution with the weight ratio of 1:3:100 for MWCNT/resin/acetone, which was then applied onto the grit-blasted steel substrates. After evaporation of acetone, an ultra-thin layer of resin pre-coating kept well-distributed MWCNTs within the micro-cavities created by grit blasting. Epoxy adhesives (with hardener) were then applied to bond the steel substrates to create MWCNTs-reinforced adhesive joints. The results show that the MWCNT pre-coating (PC) method is beneficial to strong adhesive bonding. Most importantly, the MWCNT-PC method can be easily applied for structural applications on site. In the current study, MWCNTs were simply dispersed in the acetone and resin (no hardener) solution by simple rod stirring for around 1 minute, which can be adopted for large-scale applications. Scanning electron microscopy (SEM) observations on fracture surfaces and cross sections of the MWCNT-reinforced adhesive joints showed MWCNT micro-bundles were well dispersed within the epoxy adhesive joints taking the contour of microscopically uneven substrate surfaces. [ABSTRACT FROM AUTHOR]

The dendritic Bi/Bi 2 O 3 /ZnO superhydrophobic surface (SHPS) was facilely obtained on zinc substrate via etching in 0.5 mol L −1 HCl solution for 2 min, immersing in 2 mmol L −1 Bi(NO 3 ) 3 /0.1 mol L −1 HNO 3 solution for 2.5 min and annealing treatment at 180 °C for 2 h. The wetting property results demonstrated that the superhydrophobic sample had excellent water-repellency with a static water contact angle of ~ 160° and sliding angle of ~ 0° under the optimum condition, which can be visually confirmed by the impacting droplet could rebound back immediately and roll off the horizontally placed sample. Moreover, it exhibited remarkable self-cleaning ability, buoyancy, desired stability in long-term storage in air, corrosion resistance in 3.5 wt% NaCl solution, ice-over delay at − 16 °C and durability in lab-simulated abrasion test. [ABSTRACT FROM AUTHOR]

We present the transient current response for a ZnO nanorod-based doubly transparent UV sensor. ZnO nanorods (ZNRs) are sandwiched between indium tin oxide (ITO) electrodes to make the device doubly transparent on a flexible polyethylene terephthalate (PET) substrate. The average ZNR length and diameter are 1.7 µm and 62nm, respectively, and the ITO is perfectly sputtered upon ZNR surface. All the ZNRs are c-axis oriented perpendicular to the substrate with a typical hexagonal wurtzite ZnO structure. Photoluminescence spectra show a typical high-intensity peak near 375nm and a broad peak in the visible region. UV sensing is confirmed by testing ZNR current-voltage characteristics and transient current response under UV on-off conditions for straight and inflexed ZNRs. The sensor shows a 2.3 times increase in current intensity under UV illumination at 4 V. The transient current shows a typical sinusoidal wave-like response with three prominent regions under constant voltage supply. The recovery time is almost five-times of the response time, which confirms the five-times faster boundary hole trapping in the sensor than their release on the flexible substrate. Also, the current intensity decreases for an unilluminated flexed device and increases for an UV-illuminated flexed device because of strain-induced ZNR piezotronic effects under flexible deformation. [ABSTRACT FROM AUTHOR]

Crystal growth on a Si substrate for the fabrication of a 1.2 µm GaInAsP laser diode is demonstrated via metal organic vapor phase epitaxy and lasing operation in the pulse regime at room temperature was successfully achieved. Direct wafer bonding at 400 °C for the InP thin film and Si substrate is conducted prior to the growth process is adopted. After the bonding process, epitaxial layers are grown for the monolithic integration of InP optical devices on the wafer‐bonded InP/Si substrate. The surface after crystal growth is quite smooth and contains less voids. The photoluminescence (PL) intensity of GaInAsP on the InP/Si substrate is almost equivalent to the PL intensity of InP substrate as a reference. After forming a metallic contact at the n‐Si and p‐InP sides, the chips are cleaved and the current density‐light output (I‐L) characteristics are measured. The I‐L characteristics show that there is a difference in the threshold current density between the InP/Si substrate and InP substrate. The increase in the threshold current density is dependent on the measurement temperature, and that for the InP/Si substrate was as low as 4 kA cm−2. [ABSTRACT FROM AUTHOR]

Nanoparticle agglomeration in a polymer matrix is often an intractable issue for the advancement of nanohybrid membranes, and achieving scaled-up production also requires the development of simpler, more efficient and more environmentally friendly fabrication mechanisms than what are currently used. Herein, we report a high-throughput methodology for fabricating nanodisperse hybrid membranes by directly atomizing the oligomer (no solvent) and a crosslinker solution doped with nanoparticles and then allowing the nanoparticles to crosslink rapidly on a rotating substrate surface. It has been proven that a robust and defect-free nanohybrid membrane can be fabricated within 3 min, requiring almost 2–3 orders of magnitude less time than conventional solution-coating technologies (200–6700 min). Moreover, various nanoparticles can be dispersed uniformly on a nanometer scale into the selective layer by the atomization synergistic effect, and the resulting membranes exhibit excellent overall performance and good stability for biobutanol recovery. To further demonstrate the universality of this technique, this work has been successfully extended from flat-sheet substrates to hollow-fiber and tubular substrates. In addition, the environmental impact of nanohybrid membrane-making processes has been evaluated quantitatively to further illustrate the greenness of this facile approach. [ABSTRACT FROM AUTHOR]

The purpose of this work was to optimize a single-step fabrication process of silicon (Si) cones-like nanostructures on Si(111) reconstructed substrates. The substrate temperature is the most important parameter in the Si/Si growth, due to its high influence over the surface nanostructuring and the occurrence of well defined nanocones. We investigate the effect of different substrate temperatures on the density and size distributions of Si nanocones formed during the molecular beam epitaxy (MBE) deposition of Si/Si(111) 7 × 7 reconstructed surfaces. The nanocones were characterized using scanning tunnelling microscopy (STM) and the height and the bottom area distributions of the Si nanocones were assessed. It was found that the obtained distributions are interrelated suggesting the self-similarity of the nanostructures grown during the deposition protocol. [ABSTRACT FROM AUTHOR]

Tungsten-copper co-sensitized TiO 2 nanotube films on titanium substrate, used as photoanodes in photoelectrochemical (PEC) water splitting to produce hydrogen, have been synthesized via anodization and chemical bath deposition (CBD) methods. Field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used to study the morphology and elemental composition of the synthetic samples. UV–Vis diffuse reflection spectroscopy (UV–Vis DRS) was sued to investigate the optical features of the samples. The impact of copper and tungsten ratio on the photocatalytic behavior of co-sensitized TiO 2 nanotube photoelectrodes in PEC water splitting has been investigated. High photocatalytic activity has been exhibited by the co-sensitized TiO 2 nanotube samples due to the synergistic effects of the copper and tungsten. Sample T4 had the highest photoelectrochemical activity compared with other samples. In addition, this sample exhibited outstanding photochemical stability even after four runs in the photocatalytic test. A simple method for the synthesis of high performance co-sensitized TiO 2 nanotube photocatalysts for application in solar energy conversion has thus been proposed in this work. The advantages of these new photoanodes for practical applications are low cost, ease of synthesis, high activity in visible light and excellent stability. [ABSTRACT FROM AUTHOR]

Bimetallic PtPd nanoparticles are of special interest for their tunable properties in a wide range of applications as plasmonics, energy storage, catalysis. So, in this work we present a simple and versatile method for the production of bimetallic PtPd nanoparticles on a transparent and conductive substrate, such as fluorine-doped tin oxide/glass (FTO/glass) substrate. The method is based on the deposition of thin Pt/Pd bilayers on the FTO substrate. Then, we induced the melting, alloying, and dewetting process of the Pt and Pd layers by nanosecond laser irradiation with the consequent formation of the bimetallic PtPd nanoparticles. We characterized the nanoparticles by Scanning Electron Microscopy, Rutherford backscattering spectrometry, and X-Ray Diffraction measurements. In particular, the microscopic analysis showed that the average diameter of the nanoparticles is independent on the thickness of the deposited bilayers and on the layers sequence. On the other hand, the X-ray diffraction measurements confirmed that the structure of the nanoparticles consists in a PtPd alloy structure. The formation process of the nanoparticles is, finally, discussed on the basis of the general microscopic mechanisms involved in the laser-induced melting, alloying, and dewetting of the metallic films. [ABSTRACT FROM AUTHOR]

This work explores the design and fabrication of graphene reinforced polyvinylidene fluoride (PVDF) patch-based microstrip antenna. Primarily, antenna was designed at 6GHz frequency and simulation results were obtained using Ansoft HFSS tool. Later fabrication of antenna was carried out with graphene-PVDF films as conducting patch deposited on bakelite substrate and copper as ground plane. Graphene-PVDF films were prepared using solvent casting process. The radiation efficiency of fabricated microstrip patch antenna was 48% entailing it to be adapted as a practically functional antenna. Both simulated and the practical results were compared and analyzed. [ABSTRACT FROM AUTHOR]

This paper reports on InAs/InGaAs quantum dot solar cells (QDSCs) deposited by molecular beam epitaxy (MBE) on (001) n-type silicon ( n-Si) substrates. In-situ RHEED measurements show that InAs/InGaAs QDs SC has a high crystalline structure. The dislocation density in the active layer of the InAs/InGaAs QDSC and the lattice mismatch in the GaAs layer can be reduced by using an Si rough surface buffer layer (RSi). To show the effect of the QD layers, a reference SC with the same p-i-n structure as the InAs/InGaAs QDSC, but without InAs QDs, is also grown. The two SCs were studied by sepectroscopic ellipsometry (SE), in the 1-6 eV photon energy range, photoluminescence and photocurrent measurements. The optical constants of the two devices are determined in the photon energy range 1-6 eV from the SE data. The dominant features in the dielectric function spectra at ~ 3 and ~ 4.5 eV are attributed, respectively, to the E and E critical point structures of GaAs and InAs. The low-temperature photoluminescence spectrum of the InAs/InGaAs QDSC shows ground-state emissions, respectively, from the relatively small QDs near 1081 nm and from the large QDs near 1126 nm. Photocurrent measurements confirm the improved absorption performance (up to 1200 nm) of the InAs QDs SC which is ascribed to the optical absorption from the InAs/InGaAs QDs and the Si substrate as demonstrated by SE and photoluminescence measurements. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO 2 ) with reversible metal-semiconductor transition is one of the most researched smart materials due to its near room-temperature transition at around 68 °C. Coating VO 2 (M) nanoparticles onto substrate is superior to fabrication of VO 2 (M) thin films owing to its advantages on large-scale preparation and flexible shaping. In this study, freeze-drying has been applied in a convenient precipitating and following annealing process of fabricating VO 2 (M) nanoparticles. More importantly, effects of freeze-drying and pre-freezing temperature on phase composition, size distribution and phase-transition temperature of synthesized particles have been systematically researched by varying the pretreatment conditions. It is observed that the application of freeze-drying is crucial to the formation of pure VO 2 (M), meanwhile, phase-transition temperature and size distribution of VO 2 (M) nanoparticles can be effectively reduced with lowered pre-freezing temperatures. Besides, the influence of different annealing temperatures on nanocrystallite size has been investigated, and it has been found that both the crystallinity and particle size increased as the annealing temperature was increased. Finally, the as-fabricated VO 2 (M) particles were coated onto microscopic glass substrate to characterize mid-infrared modulation performance. The coated film (made from sample pre-frozen at −50 °C) exhibits an excellent mid-infrared transmittance change of 23.3% at a fixed wavelength of 4 μm. This work demonstrates the effect of freeze-drying on the fabrication of VO 2 (M) nanoparticles and provides a facile method for large-scale preparation of VO 2 (M) nanoparticles. [ABSTRACT FROM AUTHOR]

Nonsilicon micromachining is a challenge, especially for large scale heterogeneous (hydrophilic/hydrophobic) surface fabrication. Here, mesh screen and diffusion welding technique are coupled to form a novel fabrication method. Mesh screen is used as mask. The diffusion welding technique sinters mesh screen on copper surface to form welding junction array. Chemical treatment of sintered package forms superhydrophobic nanostructures on surfaces except welding junction array. Separating mesh screen from copper substrate exposes hydrophilic dots array, corresponding to welding junction array. Thus, heterogeneous surface is created. By condensing wet air, main droplet and neighboring droplet occur on hydrophilic dot and superhydrophobic part, respectively. For horizontal surface, neighboring droplets initially generated on nanograsses behave consecutive events of coalescence, jump, and return, triggering contact/noncontact effect induced jumping. Thus, defect droplet area is formed and droplet size uniformity is broken. A nondimensional equation is proposed for the contact effect induced jumping analysis. Noncontact effect induced jumping is found for the first time. For vertical surface, droplet array behaves monodisperse size due to departure of merged neighboring droplets without returning, and equal opportunities of neighboring droplets captured by main droplets. The work opens a new way for large scale droplet array generation by controllable condensation. [ABSTRACT FROM AUTHOR]

A microliter-scale solution process was used to fabricate large-area, uniform films of silver nanowires (AgNWs). These thin films with cross-AgNWs were deposited onto Au substrates by dragging the meniscus of a microliter drop of a coating solution trapped between two plates. The hot spot density was tuned by controlling simple experimental parameters, which changed the optical properties of the resulting films. The cross-AgNW films on the Au surface served as excellent substrates for surface-enhanced Raman spectroscopy, with substantial electromagnetic field enhancement and good reproducibility. [ABSTRACT FROM AUTHOR]