Au Layer Research Articles

Gold nanoparticles coated LIPSS on GaAs for trace detection of RDX and Tetryl

Femtosecond laser-induced periodic surface structures (LIPSS) on GaAs were accomplished using ablation in the air by varying the input pulse energy (5–100 μJ). A single laser scan line was drawn at each energy, and sub-wavelength LIPSS were observed within each line. Their morphology was thoroughly analysed, and their formation mechanisms were discussed with appropriate theoretical support (SIPE-Drude model). These GaAs-LIPSS have good quality over large ablation areas, and the periodicity (663±16 nm) was nearly the same for all energies. Further, a set of GaAs-LIPSS was produced within an area of 2 × 2 mm2 utilizing an optimized energy of 5 μJ. Photoluminescence and Raman studies were performed to understand the laser-induced damage on these structures. Subsequently, these samples were coated with a 25 nm Au layer and annealed at 400 °C in ambience. The resulting plasmonic Au nanoparticles decorated GaAs-LIPSS were used as SERS substrates for detecting dye (MB) and explosive (RDX, Tetryl) molecules. Enhancement factors of ∼105 and ∼104 (lowest detected concentrations of 10−9 M and 10−5 M) were recorded for dye and explosive molecules, respectively. We believe that these results will aid in further developing GaAs-LIPSS with smaller feature sizes for improved sensing and optoelectronic applications.

Magnetron sputtering of Cu or Au buffer layer on nickel foam based on CuXCo3-XO4 to improve the performance of supercapacitors

The method of forming Cu or Au buffer layer on nickel foam (NF) by magnetron sputtering technology to enhance the energy storage capacity of following prepared supercapacitor anode material of CuXCo3-XO4 was carried out in this paper, and the feasibility of surface treatment to improve the performance of supercapacitors was discussed. The buffer layer of Cu or Au can attenuate the lattice mismatch between NF and CuXCo3-XO4, and thus greatly reducing the transfer resistance and improving the electrochemical performance of the electrode material. The effect of Au is more obvious than Cu. The transfer resistance could be decreased effectively from 1.213 Ω to 0.012 Ω after Au sputtered, and the specific capacity increased spontaneously from 442.1C/g to 744.5C/g at a current density of 1A/g. The asymmetric supercapacitor (ASC) based on the modified anode material can achieve an energy density of 51.04Wh/kg when the power density is about 800 W/kg, and 93.9 % capacity retention rate after 4000 cycles.

A Temperature-Insensitive Resonant Low-Pressure Microsensor Based on Au–Si Eutectic Wafer Bonding

This article shows a temperature-insensitive resonant low-pressure microsensor based on Au–Si eutectic wafer bonding. The microsensor comprised an silicon-on-insulator (SOI) wafer as the sensitive part, and a silicon cap packaging the SOI wafer in vacuum through Au–Si eutectic bonding to lower the thermal stresses and reduce the temperature sensitivity as no coefficient of thermal expansion mismatch exists between the SOI wafer and the silicon cap. Meanwhile, the silicon cap can counterbalance the thermal stresses induced by Au layer and Ti getter, lowering the temperature sensitivity of the microsensor from 7 to 2 Hz/°C with the thickness increasing from 300 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1500 \,\mu \text{m}$ </tex-math></inline-formula> based on numerical simulation. Characterization results showed that the low-pressure sensitivities of the microsensors were about ±6 Hz/Pa, and the temperature sensitivities were about 5 Hz/°C, indicating the microsensor was insensitive to temperature based on Au–Si eutectic wafer bonding. Furthermore, high accuracies (measurement errors within ±3.5 Pa) and satisfactory long-term stability (measurement errors within ±3 Pa after one month) were obtained under the low pressures from 0.1 to 1 kPa and temperature from −40 °C to 80 °C, indicating the better performances than previous works for the low-pressure microsensors.

Electrochemical and Optical Analysis of Various Compositions of Au and Ag Layers for Blood Cancer Prognosis

Electrochemical and Optical Analysis of Various Compositions of Au and Ag Layers for Blood Cancer Prognosis

Electromagnetic Field‐Responsive and Accurate Control of Bending in VO2 Based Micro‐Pillar Array

AbstractElectromagnetic field‐responsive mechanical deformation enables remote control of dynamic devices including micro‐robotic machines and smart surfaces. Metal–insulator transition (MIT) of vanadium dioxide (VO2) is developed for micro devices that are electrically or optically activated, but none of these is electromagnetic field‐responsive. Herein, a micro‐pillar array composed of epitaxial VO2 nanobeams that are asymmetrically coated with Cr, Au, and silicon oxide layers is demonstrated. Localized Joule heat, induced by the eddy current effect within the Cr or Au metal layer under an electromagnetic field, provides a high‐sensitive thermal response that triggers MIT of VO2, thus activates bending and relaxing of the micro‐pillars. For accurate and site‐specific control of the bending, layers of amorphous silicon oxide are added to the structure to endow tunable stiffness through electron beams‐matter interaction. These micro‐pillars are optimized to be a 2D, tractable surface on which directional transportation by remote control of the electromagnetic field in a liquid medium is realized. This discovery provides novel ideas for the design of electromagnetic field‐responsive structures.

Construction of lithophilic solid electrolyte interfaces with a bottom-up nucleation barrier difference for low-N/P ratio Li-metal batteries

The exploration of interface engineering is one of the critical maneuvers to develop high-energy-density Li metal batteries. Until now, the integrated regulation strategies on ionic conductivity of artificial solid electrolyte interphase (SEI) and lithiophilicity of anode substrate still demonstrate unsatisfactory results. Here, a robust LiF/LixMgy interfacial layer is in-situ constructed on the surface of Cu foil sputtered with Au to achieve bottom-up conductivity and lithiophilicity gradients, so as to regulate Li deposition preferentially between the ionic-conductive LiF/LixMgy SEI and high-lithiophilicity Au layer. Besides, high Young's modulus of the SEI indicates that the artificial layer has a strong ability to suppress dendrite growth during the process of cycling. As a result, the modified symmetric cells possess a long cycle lifespan over 2000 h with a low nucleation overpotential of 13.2 mV; the values are superior to most of the two-dimensional Cu-foil/plate modified strategies. Furthermore, at a low negative/positive electrode capacity (N/P) ratio of ∼ 1.5 and a lean electrolyte content of 6.0 μL g−1, the full cell can still exhibit an outstanding cycling stability for 400 cycles with a retention rate of 80.2%. This bottom-up conductivity and lithiophilicity gradients regulation strategy gives new insights for preferential Li deposition in safe positions and provides a facile approach for the construction of stable Li-metal anodes on commercial Cu foils.

Bias voltage-tuned hot-electron optical sensing with planar Au-MoS2-Au junction.

Harvesting photoexcited hot electrons in metals promises a number of benefits in optical sensing. In practice, hot-electron optical sensors with tunable performance in electrical sensitivity are still absent. Herein, we propose a design to realize tunable hot-electron optical sensing. The proposed device consists of a one-dimensional grating deposited on a planar Au-MoS2-Au junction that is used for efficient hot-electron harvesting. Photoelectric simulations show that when grating-assisted plasmonic resonance is excited, bias voltage between two Au layers can be used to manipulate the magnitude and polarity of responsivity at the working wavelength. Therefore, the change in responsivity that originates from the change in refractive index of analyte in which the device is immersed can also be tuned by applied voltage. It is found that when bias voltage is 1 V, the electrical sensitivity doubled compared with that when applied voltage is absent. We believe the bias voltage-tuned strategy that is applied to planar hot-electron harvesting junctions facilitates the development of optical sensing.

In Situ Growth of Tunable Gold Nanoparticles by Titania Nanotubes Templated Electrodeposition for Improving Osteogenesis through Modulating Macrophages Polarization.

Driving macrophages M2 polarization has attracted growing attention for improving osteogenesis. Here, the in situ growth of tunable gold nanoparticles (AuNPs) on titania nanotubes (TiNTs) array was realized by electrodeposition, with the guidance of TiNTs. The fabricated Au layer showed excellent biocompatibility with different osteoimmune effects. Briefly, the Au deposition on 5 and 10 V anodized TiNTs surface could induce RAW264.7 cells to M2 polarization, whereas the Au deposition on 20 V anodized TiNTs surface showed M1 polarization, as indicated by various markers determination through immunofluorescence staining, qPCR, Western blot, and ELISA. Furthermore, the osteogenic differentiation of MC3T3-E1 was significantly enhanced by the macrophages conditioned medium from the Au@10VNTs surface. The in vivo tests also confirmed denser and thicker new trabecula bone formation and more M2 macrophages infiltration both on and adjacent to the Au@10VNTs implant surface. In mechanism, the cytokine array analysis of macrophages conditioned medium from the Au@10VNTs surface revealed the upregulation of pro-healing cytokines such as IL-10 and VEGF and downregulation of pro-inflammatory cytokines such as IL-1β and MCSF. In addition, the NF-κB pathway was significantly inhibited. In conclusion, the electrodeposition of a Au layer guided by TiNTs is a promising strategy for reducing postoperative inflammatory reactions and improving osseointegration through modulating macrophages polarization.

Controlling Surface Wettability and Plasmonic Resonance of Au/ZnO Heterostructured Films

This work investigated the (0002) textured ZnO films without and with the addition of an Au continuous top layer and its effects on their surface wettability and plasmonic resonance characteristics. The ZnO films were directly fabricated onto glass substrates at the synthesized temperature of 300 °C via a plasma-enhanced chemical vapor deposition (PECVD) system, and the as-synthesized ZnO film exhibited an average optical transmittance value of 85%. The ultraviolet (UV) light irradiation can be applied to enhance the hydrophilicity, changing it from a hydrophobic status to hydrophilic status due to the existing and adjustable characteristics of the photocatalytic activity. On the other hand, the surface wetting/contact angle (CA) value of the ZnO film with a controllable surface wettability switched from 94° (hydrophobicity) to 44° (hydrophilicity), after it was exposed to UV light irradiation for 5 min, and stably reversed back to hydrophobicity (92°) via a post-annealed treatment using rapid thermal annealing (RTA) at 350 °C for 5 min in air. A fast, simple, and reversible method for switching between hydrophilic and hydrophobic status is claimed in this present work. The improved surface plasmonic resonance is owning to the coupled electron and photon oscillations that can be obtained and produced at the interface between the flat Au layer and ZnO (metal/metallic oxide) heterostructured films for future applications of various wide-bandgap compound semiconductors.

Realization of High Spin Injection Through Chiral Molecules and Its Application in Logic Device

Achieving highly efficient spin injection has been a challenging problem for a long time in spin logic devices. The chiral-induced spin selectivity (CISS) effect could induce spin polarization of electron transmission by chiral structure, providing a promising solution to resolve the above bottleneck. In this work, the significant CISS effect by self-assembled chiral organic molecules with helical structure was achieved on the copper (Cu) substrate covered with gold (Au) layer. We find that the spin polarization induced by the chiral molecules is more than 80%. Serving as an ultra efficient spin filter, the chiral organic molecules is demonstrated to be an effective way to generate pure spin currents and achieve highly efficient spin injection without ferromagnetic electrodes or external magnetic field. Based on these properties, a CISS based reconfigurable logic device is proposed. Due to the high spin injection efficiency, this CISS based device can realize 6 different logic operations with low energy consumption (1.2 pJ) and high speed (3.6 ns).

OXIDE LAYER CHARACTERIZATION OF AlMg2 CLADDING OF IRRADIATED U3Si2/Al FUEL WITH 4,8 gU/cm3 DENSITY

OXIDE LAYER CHARACTERIZATION OF AlMg2 CLADDING OF IRRADIATED U3Si2/Al FUEL WITH 4,8 gU/cm3 DENSITY. To investigate the performance of AlMg2 cladding in the U3Si2/Al dispersion fuel, oxide layer characterization of AlMg2 cladding of the irradiated U3Si2/Al fuel with 4.8 gU/cm3 density was conducted. The oxide layer on the surface of AlMg2 cladding is one of the changes that occur on the cladding after the U3Si2/Al fuel plate has been irradiated in the RSG-GAS reactor to a burn-up of ∼40%. The characterization and observation of the oxide layer was conducted using SEM (Scanning Electron Microscope) and Energy-dispersive X-ray spectroscopy (EDS). Samples with a size of 3x3 mm were taken from the middle of the fuel plate (middle position). After cutting, metallographic preparation includes mounting, grinding, polishing, and ultrasonic cleaning. SEM preparation was carried out by sputter coating using Au layer. The oxide layer on the AlMg2 cladding has a thickness of 10.3 µm with a uniformly distributed cracks along the oxide layer.Keyword: LEU, uranium-silicide, post-irradiation examination, AlMg2 cladding, oxide layer.

Wafer-Scale Room-Temperature Bonding of Smooth Au/Ti-Based Getter Layer for Vacuum Packaging.

This study demonstrates room-temperature bonding using a getter layer for the vacuum packaging of microsystems. A thick Ti layer covered with an Au layer is utilized as a getter layer because it can absorb gas molecules in the package. Additionally, smooth Au surfaces can form direct bonds for hermetic sealing at room temperature. Direct bonding using a getter layer can simplify the vacuum packaging process; however, typical getter layers are rough in bonding formation. This study demonstrates two fabrication techniques for smooth getter layers. In the first approach, the Au/Ti layer is bonded to an Au layer on a smooth SiO2 template, and the Au/SiO2 interface is mechanically exfoliated. Although the root-mean-square roughness was reduced from 2.00 to 0.98 nm, the surface was still extremely rough for direct bonding. In the second approach, an Au/Ti/Au multilayer on a smooth SiO2 template is bonded with a packaging substrate, and the Au/SiO2 interface is exfoliated. The transferred Au/Ti/Au getter layer has a smooth surface with the root-mean-square roughness of 0.54 nm and could form wafer-scale direct bonding at room temperature. We believe that the second approach would allow a simple packaging process using direct bonding of the getter layer.

Determination of anisotropy in magnetic moments at the interface of Au/Co/Au thin film without a thickness-dependent experiment

Anisotropy in the magnetic moments at the interface of a Co thin film sandwiched by Au layers is determined without thickness-dependent experiment, by using the depth-resolved x-ray magnetic circular dichroism (XMCD) technique, in which the fluorescence soft x rays are collected at different detection angles. By combining the depth-resolved XMCD technique with incidence angle-dependent XMCD sum rules, the spin magnetic moment, perpendicular and in-plane orbital magnetic moments, and perpendicular and in-plane magnetic dipole moments are separately estimated at the interface and inner layers of the Co thin film. It is revealed that the perpendicular orbital magnetic moment is significantly larger than the in-plane one at the interface, while the inner Co layers exhibit a small opposite tendency. It is verified that the interfacial Co has large interfacial anisotropy in the orbital magnetic moment even in the relatively thick-film region.

Synthesis of a Gold-Inserted Iron Disilicide and Rutile Titanium Dioxide Heterojunction Photocatalyst via the Vapor-Liquid-Solid Method and Its Water-Splitting Reaction.

A solid-state Z-scheme system is constructed whereby rutile titania (TiO2) and beta-iron disilicide (β-FeSi2) were combined to act as oxygen (O2)- and hydrogen (H2)-evolution photocatalysts, respectively, connected by gold (Au). β-FeSi2 island grains with diameters in the 0.5-2 μm range were formed on the surface of Au-coated TiO2 powder by the co-sputtering method. On the surface of TiO2 powder, the Au-Si liquidus phase was obtained via a Au-Si eutectic reaction, which contributed to the selective deposition and crystallization of β-FeSi2 island grains onto Au. After the loading of the H2-evolution cocatalysts platinum and chromium oxide onto β-FeSi2, the system obtained catalyzed the evolution of H2 and O2 in a stoichiometric ratio from pure water under ultraviolet light irradiation. The transfer of photoexcited electrons in the conduction band (CB) of β-FeSi2 to Pt causes the reduction of protons to H2, and the photogeneration of holes in the valence band (VB) of TiO2 causes the oxidation of water to O2. In addition, the photogenerated holes in the VB of β-FeSi2 and the photoexcited electrons in the CB of TiO2 combined with each other in the Au layer, affording the completion of the overall photocatalytic water-splitting.

High-Temperature 2D Optical Relaxation Visualizes Enhanced Oxygen Exchange Kinetics at Metal-Mixed Conducting Oxide Interfaces.

Solid-state heterointerfaces are of interest for emergent local behavior that is distinct from either bulk parent compound. One technologically relevant example is the case of mixed ionic/electronic conductor (MIEC)-metal interfaces, which play an important role in electrochemistry. Metal-MIEC composite electrodes can demonstrate improved catalytic activity vs single-phase MIECs, improving fuel cell efficiency. Similarly, MIEC surface reaction kinetics are often evaluated using techniques that place metal current collectors in contact with the surface under evaluation, potentially altering the response vs the native surface. Techniques enabling direct and local in situ observation of the behavior at and around such heterointerfaces are needed. Here, we develop a spatially resolved optical transmission relaxation (2D-OTR) method providing continuous evaluation of local, high-temperature, controlled atmosphere defect kinetics across a ∼1 cm2 sample area simultaneously in a contact-free manner. We apply it to observe the spatial variance of oxygen incorporation and evolution rates at ∼525-620 °C, in response to step changes in oxygen partial pressure, on MIEC SrTi0.65Fe0.35O3-x films as a function of distance from porous Pt and Au layers. Using this model geometry, we find significant enhancements in kinetics adjacent to the metals that decay over a few millimeter distance. To extract kinetic parameters, we fit the short-term optical data (initial portion of relaxations) with an exponential decay function appropriate for surface-exchange-limited kinetics, yielding apparent surface exchange coefficients (kchem) with spatial resolution, decreasing with distance from the metal. To understand the kinetic processes governing the complete (long-term) optical relaxations, we performed COMSOL simulations, which demonstrated that a combination of laterally varying kchem and in-plane diffusion controls the observed kinetics over the full time range. Further support for spatially varying kchem comes from demonstrations of changing surface and bulk chemistry vs distance from the metal-MIEC interface, by X-ray photoelectron and optical absorption spectroscopies, respectively. Although microporous Pt and Au are not excellent electrodes in isolation, both metals exert a synergistic effect on the oxygen surface exchange rate in the presence of the mixed conducting film.

3D plasmonic hot spots network via gold decorated deep micro-porous silicon exhibiting ultrahigh-SERS enhancement with application to explosives detection

Microporous deep (12 µm depth) silicon substrate coated with optimum Au layer is fabricated for ultrahigh SERS enhancement factor and employed for explosives trace detection. Being microporous with quasi-periodicity, short lived extended plasmons can be excited via scattering and coupled to localized ones thus providing ultrahigh local optical field, and the SERS ultrahigh enhancement is achieved. SERS activity of the substrate is checked using 4-ATP monolayer immobilized over the proposed substrate and analyzed using two different methods including peak absolute intensity and peak ratios, to find best suitable method for higher reproducibility. The obtained enhancement factor for Raman signal is found to be the order of 106–107, explained due to the existence of 3D hot-spot network and coupling between localized to extended plasmons. The coupling is verified through the Rabi splitting observed in the reflectivity dip. A 2–3 times fewer signal variability is obtained using peak ratio between highest peak intensity of Raman receptor and that of the substrate. The substrate is then employed for picric acid sensing providing the detection limits of 7.48 nM and 2.87 nM, determined based on peaks height and ratio measurements respectively. The proposed work suggests deep micro-porous silicon coated with 200 nm Au layer deposited over a large area as promising candidate for SERS and sensing of ultra-trace amount of chemicals.

Morphology and Electrochemistry Drive Corrosion of Electroless Nickel Immersion Gold Films: A Multi-Technique Analysis

Electroless nickel immersion gold (ENIG) is a common surface finish for high-reliability microelectronics circuitry due to its good solderability, corrosion resistance, layer thickness uniformity and applicability for fine pitch applications1. ENIG deposition is a multistep process in which a 3 to 6 micron (118-236 μ-in) layer of electroless nickel (i.e. Ni-P) is deposited onto the substrate material (typically copper), followed by a galvanic displacement reaction replacing the surface layer of Ni with 0.04 to 0.1 microns (1.6 to 4 μ-in) of gold (Au). Despite ENIG’s widespread use, it continues to suffer from a failure mode known as “black pad” or Ni hypercorrosion during immersion gold deposition2. A cohesive mechanistic explanation for the occurrence of Ni hypercorrosion is not yet established despite extensive study. Recent approaches have attempted to characterize in-situ the influence of bath chemistry; however, the competing influence of all variables of the ENIG process (e.g. temperature, pH, solution chemistry, volume mixing, surface morphology, etc.) make global mechanistic conclusions challenging if not impossible experimentally3. Instead, the work here aims to develop tools to assess an ENIG film of unknown origin or deposition conditions for the risk of corrosion. Therefore, this study utilizes a combination of surface characterization via x-ray photoelectron spectroscopy (XPS) depth profiling and transmission electron microscopy (TEM) imaging and electrochemical characterization via cyclic polarization (CP) and scanning vibrating electrode technique (SVET) to build a multi-technique analysis of ENIG failures.ENIG samples with identical geometries and plating requirements from two domestic vendors (A & B) were obtained. XPS with argon ion sputtering allows for comparison of atomic concentration of Ni, Au and P in ENIG films through their depth as a function of the number of sputter cycles. XPS results show that Vendor A films have a high concentration of Ni in the Au layer and a lower concentration of P near the Au-Ni interface, whereas Vendor B films have a low concentration of Ni in the Au layer and a higher concentration of P near the Au-Ni interface. This indicates a more porous morphology in Vendor A versus B films. SVET is an electrochemical scanning probe tool which allows for real-time observation of cathodic and anodic currents (in a 0.35% NaCl solution) representing existing and developing defect sites on ENIG surfaces. SVET experiments show that Vendor A and B samples exhibit preferential anodic currents on ENIG surfaces corresponding to Ni hypercorrosion defects. Focused ion beam (FIB) lift-outs from SVET samples viewed in TEM give ex-situ confirmation that SVET observations align with the real metal layer structure and chemistry as well as confirming the presence and location of corrosion products. CP curves for samples of each film in a 0.35% NaCl solution demonstrate that both Vendor A and Vendor B films exhibit effective corrosion rates above 1.0 mil per year which is on the order of bare Cu wire in the same electrolyte. Overall, a distinct difference in film morphology between Vendor A and B samples exists; however, both films exhibit substantial electrochemical activity in solution indicating corrosion susceptibility. Taken together, these results show that Ni hypercorrosion can be driven by at least two distinct mechanisms: high porosity in the Au film leading to enhanced Ni migration and reaction at the Au surface; or, P enrichment at the Au-Ni interface leading to enhanced P migration and a more electronegative surface composition. Future work will build out characterization of additional ENIG samples to establish a failure matrix for ENIG films, encompassing a wider variety of unique mechanisms. D. Goyal, T. Lane, P. Kinzie, C. Panichas, K. M. Chong, and O. Villalobos, in "52nd Electronic Components and Technology Conference 2002.(Cat. No. 02CH37345)", p. 732-739. IEEE, 2002.R. Ramanauskas, A. Selskis, J. Juodkazyte, and V. Jasulaitiene, Circuit World, (2013).A. Accogli, E. Gibertini, G. Panzeri, A. Lucotti, and L. Magagnin, Journal of The Electrochemical Society, 167 (8), 082507 (2020). SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525

P‐8.5: Research on LED Pad Design in Glass‐based Mini LED Backlight

In the past two years, the field of glass-based mini LED backlight has developed rapidly. In this article, experimental research on the design of the LED pad is conducted, including the Cu thickness, stack-up structure and pad size. The experimental results show that after the LED is solidified, the copper at the bonding pad is consumed and intermetallic compounds (IMC) are formed. The IMC has a granular morphology, dispersed in the solder layer. The main components of IMC are Cu6Sn5 and Ag3Sn. When the copper thickness on the pad increases from 0.6um to 3.6um in turn, the proportion of IMC in the solder layer increases significantly. The formation of IMC can improve the connection strength, but too much IMC will reduce the mechanical strength and the rework times. The fundamental method is to suppress the reaction rate of the Cu layer and the SnAgCu solder. The Electroless Nickel Immersion Gold (ENIG) process is a feasible method, because the Ni layer can effectively reduce the formation rate of IMC, and Au layer can effectively prevent the Cu of the LED pad from being oxidized. In addition, when the expansion of the BP pad relative to the LED bump increases, the die bonding yield is also significantly improved. These verification results could provide reference for future mini LED product design and production.

New, epitaxial approach to SERS platform preparation – InP nanowires coated by an Au layer as a new, highly active, and stable SERS platform

The deposition of a plasmonic metal layer on a highly ordered, nanostructured semiconducting layer is an important method of SERS platform preparation. In this contribution to the best of our knowledge, we will describe for the first time a highly ordered InP nanowire surface coated by an Au layer as a highly efficient and stable SERS platform. The influence of various factors affecting InP nanowire growth have been studied and the structural and optical properties examined. The SERS measurements showed very high SERS enhancement factors for the InP@Au SERS platforms produced. The calculated SERS enhancement factor for the InP nanowires covered with ca. 220 nm thick layer of Au was 2.3∙106, which is one of the highest SERS enhancement factors for the gold-based SERS platforms so far. The studied samples exhibit high repeatability from point to point measurement, lower than 10 % RSD. Additionally, there was no decrease in the measured intensity of the SERS spectra in time, even after 3 months.

Au Wire Ball Welding and Its Reliability Test for High-Temperature Environment.

The long-term application of sensors in a high-temperature environment needs to address several challenges, such as stability at high temperatures for a long time, better wiring interconnection of sensors, and reliable and steady connection of the sensor and its external equipment. In order to systematically investigate the reliability of thin coatings at high temperatures for a long time, Au and Cr layers were deposited on silicon substrates by magnetron sputtering. Additionally, samples with different electrode thicknesses were annealed at different temperatures for a varied duration to study the effect of electrode thickness, temperature, and duration on the reliability of samples. The results of tensile and probe tests before and after heat treatment revealed that the mechanical strength and electrical properties have changed after annealing. In addition, the bonding interface was analyzed by a cross-sectional electron microscope. The analysis showed that long-term continuous high-temperature exposure would result in thinning of the electrode, formation of pores, recrystallization, and grain growth, all of which can affect the mechanical strength and electrical properties. In addition, it was observed that increasing the thickness of the gold layer will improve reliability, and the test results show that although the thin metal layer sample is in poor condition, it is still usable. The present study provides theoretical support for the application of thin coatings in high temperatures and harsh environments.