Substrate Resistance Research Articles

Understanding the tribo-corrosion behaviors and mechanism of Si/N-DLC films in marine environment

Herein, a series of Si/N-DLC films were deposited by modulating the flow rate of the N2 precursor, with the aim of elucidating their tribo-corrosion behaviors and underlying mechanisms in a marine environment. The results indicate that the deposited Si/N-DLC films significantly enhance the substrate's resistance to tribo-corrosion in seawater. This improvement initially increases and then decreases, a trend attributed to the toughness of the film. The fundamental tribo-corrosion mechanism involves a solid-liquid composite lubrication composed of Si/N-DLC film and seawater, and it is dependent on the adequacy of liquid-phase lubrication, the graphitization degree at the friction interface, and the film toughness. This process is coupled with the blockage of corrosion pathways due to the diffusion of corrosion products, the formation of tribo-chemical products, and the generation of wear debris.

Construction of pyrimidine derivatives-copper enzyme mimics as colorimetric sensing elements for efficient detection of phenolic compounds and hydrogen peroxide

As concerns about environmental pollution grow, the rapid identification and quantification of pollutants have become increasingly vital. In this work, a series of pyrimidine derivatives-Cu enzyme mimics (Cytosine-Cu, Cytidine-Cu, and CMP-Cu) with laccase- and peroxidase-like activity were prepared through the coordination of Cu2+ with different pyrimidine derivatives (PDs). The PDs-Cu enzyme mimics contain high levels of Cu+ and N−Cu coordination structures, which provide sufficient catalytic sites for the substrates. Compared with natural enzymes and other nanozymes, PDs-Cu demonstrate superior substrate affinity, catalytic efficiency, stability, and resistance to interference. It was found that PDs-Cu enzyme mimics have different catalytic activities towards different phenolic compounds. Therefore, a three-channel colorimetric sensor array (CSA) was successfully developed utilizing PDs-Cu as the sensing elements. The CSA can accurately identify different phenolic compounds and their mixtures in seawater and simulated wastewater. Additionally, a colorimetric method for detecting H2O2 in eye drops was developed, featuring a detection range of 0.1–10.0μM and a limit of quantification of 0.1μM. This research not only provides a flexible protocol for regulating the catalytic activity of enzyme mimics, but also provides important inspiration for the development of methods for rapid identification and detection of contaminants in the environmental water.

Synergy between Nitrogen Removal and Fermentation Bacteria Ensured Efficient Nitrogen Removal of a Mainstream Anammox System at Low Temperatures.

Simultaneous partial nitrification, anammox, denitrification, and fermentation (SNADF) is a novel process achieving simultaneous advanced sludge reduction and nitrogen removal. The influence of low temperatures on the SNADF reactor was explored to facilitate the application of mainstream anammox. When temperature decreased from 32 to 16 °C, efficient nitrogen removal was achieved, with a nitrogen removal efficiency of 81.9-94.9%. Microbial community structure analysis indicated that the abundance of Candidatus Brocadia (dominant anaerobic ammonia oxidizing bacteria (AnAOB) in the system) increased from 0.03% to 0.18%. The abundances of Nitrospira and Nitrosomonas increased from 1.6% and 0.16% to 2.5% and 1.63%, respectively, resulting in an increase in the ammonia-oxidizing bacteria (AOB) to nitrite-oxidizing bacteria (NOB) abundance ratio from 0.1 to 0.64. This ensured sufficient nitrite for AnAOB, promoting nitrogen removal. In addition, Candidatus Competibacter, which plays a role in partial denitrification, was the dominant denitrification bacteria (DNB) and provided more nitrite for AnAOB, facilitating AnAOB enrichment. Based on the findings from microbial correlation network analysis, Nitrosomonas (AOB), Thauera, and Haliangium (DNB), and A4b and Saprospiraceae (fermentation bacteria), were center nodes in the networks and therefore essential for the stability of the SNADF system. Moreover, fermentation bacteria, DNB, and AOB had close connections in substrate cooperation and resistance to adverse environments; therefore, they also played important roles in maintaining stable nitrogen removal at low temperatures. This study provided new suggestions for mainstream anammox application.

Ozone strengthens the ex vivo but weakens the in vivo pathway of the microbial carbon pump in poplar plantations

Elevated ozone (eO3) and atmospheric nitrogen (N) deposition are important climate change components that can affect plant growth and plant-soil-microbe interactions. However, the understanding of how eO3 and its interaction with N deposition affect soil microbially mediated carbon (C) cycling and the fate of soil C stocks is limited. This study aimed to test how eO3 and N deposition affected soil microbial metrics (i.e., respiration, enzyme activities, biomass, necromass, and community composition) and resulting soil organic C (SOC) fractions in the rhizosphere of poplar plantations with different sensitivity to O3. Exposure to O3 and/or N deposition for four years was conducted within a free-air O3 concentration-enrichment facility. Elevated O3 reduced soil microbial respiration and biomass C but enhanced the enzymatic acquisition of C (i.e., potential soil hydrolase and oxidase activity) and shifted to a fungi-dominated community composition. These responses suggest that microbial C availability decreased and microbes allocated more energy to obtain C and nutrients from biochemically resistant substrates under eO3. Elevated O3 decreased bacterial necromass C and total necromass C, which could explain the observed decreases in mineral-associated organic C and SOC. The effects of eO3 on soil microbial C availability and community composition were strengthened by N addition, whereas there were no differences in the below-ground effects of eO3 between the two poplar clones. Taken together, the increased soil extracellular enzyme activities and slightly increased particulate organic C content suggest that the microbial C pump pathway via microbial ex vivo modification was strengthened by eO3, whereas the pathway via microbial in vivo turnover was weakened, as suggested by the decreases in soil microbial respiration, biomass, necromass, and mineral-associated organic C. Our study provides evidence that aboveground eO3 effects on trees may affect belowground microbial processing of organic matter and ultimately the persistence of SOC.

Photothermal driven BMSCs osteogenesis and M2 macrophage polarization on polydopamine-coated Ti3C2 nanosheets/poly(vinylidene fluoride trifluoroethylene) nanocomposite coatings

Mild thermal stimulation plays an active role in bone tissue repair and regeneration. In this work, a bioactive polydopamine/Ti3C2/poly(vinylidene fluoride trifluoroethylene) (PDA/Ti3C2/P(VDF-TrFE)) nanocomposite coating with excellent near-infrared light (NIR)-triggered photothermal effect was designed to improve the osteogenic ability of implants. By incorporating dopamine (DA)-modified Ti3C2 nanosheets into the P(VDF-TrFE) matrix and combining them with alkali initiated in situ polymerization, the resulting PDA/Ti3C2/P(VDF-TrFE) nanocomposite coating gained high adhesion strength on Ti substrate, excellent tribological and corrosion resistance properties, which was quite important for clinical application of implant coatings. Cell biology experiments showed that NIR-triggered mild thermal stimulation on the coating surface promoted cell spreading and growth of BMSCs, and also greatly upregulated the osteogenic markers, including Runt-Related Transcription Factor 2 (RUNX2), alkaline phosphatase (ALP), osteopontin (OPN), osteocalcin (OCN). Simultaneously, the synthesis of heat shock protein 47 (HSP47) was significantly promoted by the mild thermal stimulation, which strengthened the specific interaction between HSP47 and collagen Ⅰ (COL-Ⅰ), thereby activating the integrin-mediated MEK/ERK osteogenic differentiation signaling pathway. In addition, the results also showed that the mild thermal stimulation induced the polarization of macrophages towards M2 phenotype, which can attenuate the inflammatory response of injured bone tissue. Antibacterial results indicated that the coating exhibited an outstanding antibacterial ability against S. aureus and E. coli. Conceivably, the versatile implant bioactive coatings developed in this work will show great application potential for implant osseointegration.

Saturation Mutagenesis and Molecular Modeling: The Impact of Methionine 182 Substitutions on the Stability of β-Lactamase TEM-1.

Serine β-lactamase TEM-1 is the first β-lactamase discovered and is still common in Gram-negative pathogens resistant to β-lactam antibiotics. It hydrolyzes penicillins and cephalosporins of early generations. Some of the emerging TEM-1 variants with one or several amino acid substitutions have even broader substrate specificity and resistance to known covalent inhibitors. Key amino acid substitutions affect catalytic properties of the enzyme, and secondary mutations accompany them. The occurrence of the secondary mutation M182T, called a "global suppressor", has almost doubled over the last decade. Therefore, we performed saturating mutagenesis at position 182 of TEM-1 to determine the influence of this single amino acid substitution on the catalytic properties, thermal stability, and ability for thermoreactivation. Steady-state parameters for penicillin, cephalothin, and ceftazidime are similar for all TEM-1 M182X variants, whereas melting temperature and ability to reactivate after incubation at a higher temperature vary significantly. The effects are multidirectional and depend on the particular amino acid at position 182. The M182E variant of β-lactamase TEM-1 demonstrates the highest residual enzymatic activity, which is 1.5 times higher than for the wild-type enzyme. The 3D structure of the side chain of residue 182 is of particular importance as observed from the comparison of the M182I and M182L variants of TEM-1. Both of these amino acid residues have hydrophobic side chains of similar size, but their residual activity differs by three-fold. Molecular dynamic simulations add a mechanistic explanation for this phenomenon. The important structural element is the V159-R65-E177 triad that exists due to both electrostatic and hydrophobic interactions. Amino acid substitutions that disturb this triad lead to a decrease in the ability of the β-lactamase to be reactivated.

Improvement of linearity in trap-rich substrates for radio frequency applications: Which of donor and acceptor trap is the best?

This paper investigates the effect of volume traps intentionally introduced into a silicon-on-insulator (SOI) substrate by inserting a layer of polysilicon beneath buried oxide. In radio frequency applications, this type of substrate, referred to as trap-rich, is known to considerably reduce the generation of harmonics resulting from the parasitic non-linear charge dynamics introduced by the substrate handler under the buried oxide. This analysis focuses on a test vehicle in the form of an integrated coplanar waveguide on two types of substrates, namely, high-resistivity SOI substrates with and without a trap-rich layer. From a modeling point of view, a simulation methodology is implemented in order to convert the 3D simulation of the coplanar waveguide into a 2D treatment that takes into account the wave propagation effect associated with the distributed nature of the transmission line. As a first step, this modeling strategy is implemented to reproduce the effect of increasing substrate resistivity on 2nd and 3rd harmonic reductions, leading to an excellent agreement with experimental data. Building on this validation of the simulation method, we have opted to simulate the non-linear response of the transmission line on the SOI trap-rich substrate by simplifying the trap distribution model. To avoid the adoption of unverified and strongly process-dependent trap distributions across the bandgap, a midgap monovalent trap density has been introduced, either acceptor or donor density. A monovalent density of acceptor traps with a concentration of 1016 cm−3 and a carrier lifetime of 0.1 ns has been shown to reproduce the experimental data very accurately with a substantial reduction in 2nd and 3rd harmonics. A detailed analysis of the displacement current waveforms explains the beneficial role of acceptor traps compared with donor traps.

Effect of Si substrate conductivity on surface acoustic wave resonator

A surface acoustic wave (SAW) filter’s bandwidth and quality are determined by its resonators’ electromechanical coupling coefficient (k2) and impedance ratio (IR). Research commonly focuses on the effects of piezoelectric material and cutting direction on these parameters. This paper investigates the effect of the conductivity of the Si substrate on k2 and IR through finite element method (FEM) simulations. A new model based on the modified Butterworth-van-Dyke (MBVD) model is presented. This new model takes into account the substrate parasitic capacitance and resistance to predict resonator performance on low resistivity (LR) Si piezoelectric on insulator (POI) substrates. Both high resistivity (HR) Si and LR-Si are utilized to fabricate POI SAW resonators, which are subsequently tested. The high conductivity of the Si support layer leads to a decrease in both k2 and IR. By employing Si substrates with different resistances during fabrication, it becomes possible to manufacture resonators with varying k2 values, thus meeting diverse bandwidth requirements for filters.

Simulation investigation of effects of substrate and thermal boundary resistance on performances of AlGaN/GaN HEMTs

The temperature distributions and thermal resistances of the GaN HEMTs fabricated on different substrates (sapphire, Si, SiC and diamond) with Mo/Au interlayers were calculated and analyzed by numerical simulation. The results show that the GaN HEMT on the diamond substrate exhibits the lowest channel temperature and thermal resistance, and the thermal resistance rises with the increase of the thermal boundary resistance (TBR) for all the GaN HEMTs with the different substrate materials. Meanwhile, the high TBR (2 × 10−7 m2·K/W) severely hinders the heat exchange between the GaN layer and the substrate, which makes it difficult for the heat flux to pass through the barrier. Even diamond with high thermal conductivity can hardly reduce the channel temperature of the device. Therefore, TBR must be reduced so that the heat flux can be dissipated through a high thermal conductivity substrate. In addition, the Mo/Au interlayer generates a lower thermal boundary resistance, which has little effect on the channel temperature, thermal resistance and interfacial temperature discontinuity of GaN HEMTs.

A high-performance slotted bow-tie nano graphene antenna for optical frequency application with silicon lens and stacked aligning layers

A new Graphene nano-antenna has been designed and proposed in this paper for optical frequency applications with optimized gain performance. The proposed design uses a Silicon Lens and subsequent layers to match the dielectric constant between the antenna and air. The different patch materials are taken and studied for better results. The proposed antenna has been simulated upon a Highly resistive silicon substrate having a high dielectric constant of 11.9. The base of the proposed antenna is designed on a square substrate of 6000μm length and 300μm height. The slotted “bow-tie” antenna is placed on it with an aperture area of 156.8μm×42μm. A silicon layer is placed over it for improved performance. Further, it has been optimized by placing 16 stacked aligning layers to match the dielectric constants. The gain and efficiency improvement are achieved after each layer or coating over the lens. The resonant frequencies obtained are 0.4THz, 1THz, and 2.2THz having triple bands. The maximum gain obtained is 36.89 dB and the maximum radiation efficiency is 97%. HFSS 21.0 software is the used environment for the simulation and optimization.

Decoding the role of oxidative stress resistance and alternative carbon substrate assimilation in the mature biofilm growth mode of Candida glabrata

BackgroundBiofilm formation is viewed as a vital mechanism in C. glabrata pathogenesis. Although, it plays a significant role in virulence but transcriptomic architecture and metabolic pathways governing the biofilm growth mode of C. glabrata remain elusive. The present study intended to investigate the genes implicated in biofilm growth phase of C. glabrata through global transcriptomic approach.ResultsFunctional analysis of Differentially expressed genes (DEGs) using gene ontology and pathways analysis revealed that upregulated genes are involved in the glyoxylate cycle, carbon-carbon lyase activity, pre-autophagosomal structure membrane and vacuolar parts whereas, down- regulated genes appear to be associated with glycolysis, ribonucleoside biosynthetic process, ribosomal and translation process in the biofilm growth condition. The RNA-Seq expression of eight selected DEGs (CgICL1, CgMLS1, CgPEP1, and CgNTH1, CgERG9, CgERG11, CgTEF3, and CgCOF1) was performed with quantitative real-time PCR (RT-qPCR). The gene expression profile of selected DEGs with RT-qPCR displayed a similar pattern of expression as observed in RNA-Seq. Phenotype screening of mutant strains generated for genes CgPCK1 and CgPEP1, showed that Cgpck1∆ failed to grow on alternative carbon substrate (Glycerol, Ethanol, Oleic acid) and similarly, Cgpep1∆ unable to grow on YPD medium supplemented with hydrogen peroxide. Our results suggest that in the absence of glucose, C. glabrata assimilate glycerol, oleic acid and generate acetyl coenzyme-A (acetyl-CoA) which is a central and connecting metabolite between catabolic and anabolic pathways (glyoxylate and gluconeogenesis) to produce glucose and fulfil energy requirements.ConclusionsThe study was executed using various approaches (transcriptomics, functional genomics and gene deletion) and it revealed that metabolic plasticity of C. glabrata (NCCPF-100,037) in biofilm stage modulates its virulence and survival ability to counter the stress and may promote its transition from commensal to opportunistic pathogen. The observations deduced from the present study along with future work on characterization of the proteins involved in this intricate process may prove to be beneficial for designing novel antifungal strategies.

Pressure‐Induced Effects on BaPbO3: A Prospectively Valuable Material for Piezoelectric Applications via DFT

AbstractEmploying density functional theory within the Wien2k code, first‐principle calculations are conducted to explore the impact of applied pressure up to 80 GPa on the structural, mechanical, thermal, and electronic characteristics of BaPbO3. Demonstrating metallic behavior with ductile attributes, BaPbO3 exhibits a decreasing anisotropic nature under escalating pressure. Evaluation of cubic elastic constants, optimization curves, and enthalpy of formation indicates the compound's mechanical and thermodynamic stability under high pressure conditions. Calculated values of C11 and C44 reflect heightened resistance to unidirectional compression and increased stiffness under pressure. These mechanical properties position BaPbO3 as a promising candidate for diverse industrial applications across varying pressure ranges, including utilization in piezoelectric materials (0–20 GPa) and high‐pressure sensors. Additionally, charge density contours suggest a combination of ionic (Ba─Pb) and covalent bonding (Pb─O) within the compound's constituent atoms. The material can exhibit potential applications as a piezoelectric sensor at 0–20 GPa, high‐pressure actuators ≈20 GPa, and as a high melting temperature resistive substrate for laser welding and cutting materials.

Molybdenum-14Rhenium alloy—The most promising candidate for high-temperature semiconductor substrate materials

The development of emerging high-temperature-resistant semiconductor materials is of great significance for the stability of signals and the reliability of sensors during extreme probing processes such as deep earth and space. However, current reports only focused on the properties of the semiconductor materials, neglecting the high-temperature-resistant properties of subsidiary components, such as substrate. In this study, for the first time, the feasibility of the Molybdenum-14Rhenium (Mo-14Re) alloy as a high-temperature semiconductor substrate material was verified at five temperature points (25 ℃ (room temperature, Rt.), 100 ℃, 200 ℃, 300 ℃, and 400 ℃, respectively). The results showed that the hardness (2.8 GPa to 2.4 GPa) of the Mo-14Re alloy changed slightly during the temperature up to 400 ℃; the Mo-14Re alloy generated protective Mo6+ and Re3+ oxides at different temperatures, which enhanced its oxidation resistance; the thermal expansion coefficient of the Mo-14Re alloy was 5.04 × 10−6/℃ at 400 ℃, which can be perfectly adapted to semiconductor components, such as silicon, silicon nitride, and gallium nitride. Simultaneously, the Mo-14Re alloy combined appropriate thermal conductivity, making it the most promising candidate for a new generation of high-temperature semiconductor substrate materials. This study can promote the application of semiconductor materials in extreme environments, such as high temperatures. Concurrently, this study can promote the development of deep earth exploration and aerospace fields and guide the selection of emerging high-temperature resistant substrate materials.

Two HVCMOS active pixel ASIC designs for the Measurement of GCR and SEP with a combined dynamic range of >80 dB

The design of HVCMOS detectors for measuring Galactic Cosmic Rays (GCR) and Solar Energetic Particles (SEP) is presented, with the goal of covering a very wide dynamic range (from ∼0.5 fC to pC). Two different pixel designs are shown, one with low gain tailored to high energy depositions and one with high gain for low energy depositions. Both designs utilize a sensing diode consisting of a fully-depleted, high resistivity substrate and a segmented deep n-well on top. LFoundry 0.15 μm technology is used. The design choices are backed by simulation results and preliminary measurements.

Improved enantioselective permeation in cellulose membrane-supported metal–organic framework via polyvinylpyrrolidone as the pore-forming agent

Chiral membranes have limited permeability and selective trade-off, which has been a major problem in chiral membrane separations. To address this issue, the carboxylated cellulose (CC) membranes were prepared with small pore size and low resistance substrate by regulating the amount of polyvinylpyrrolidone (PVP) and casting solution, and the CC@CuLBH composite membrane with chiral separation capability was fabricated by in situ formation of well-dispersed [Cu(L-mal)(Bipy)]·H2O (CuLBH) with the carboxyl group on the surface of CC membrane as the metal anchor points. Under the optimal conditions, the CC@CuLBH membrane showed good chiral separation ability with an ee value of 60% for R-1-(1-naphthyl)ethanol (R-NE). Compared with the CC/CuLBH membrane formed by physical blend, the CC@CuLBH membrane exhibited improved enantioselective permeation for R-NE enantiomer. Both the unique chiral microenvironment of CuLBH and the regular pore structure of CC membrane, in addition to their synergistic effects resulted in the highly permeable and enantioselectivity for the CC@CuLBH composite membrane, which broadened the preparation method of chiral membrane.

Room-temperature NH3 gas sensing of S-hyperdoped silicon: Optimization through substrate resistivity

Sulfur-hyperdoped black silicon (S-BSi) prepared by femtosecond laser-assisted etching in SF6 atmosphere has dual characteristics of large specific surface area and super-doped impurities, and its physics and applications have attracted extensive attention. The room-temperature NH3 gas sensing capability of the samples is studied in the conductance mode. The S-BSi-based sensors exhibit a response to NH3 gas. Interestingly, their responsivity varies with the substrate resistance, and the sensor based on an appropriate substrate resistance shows the optimal responsivity. Additionally, the device demonstrates fast response and recovery speed, as well as good selectivity. The evolution of the responsivity and response/recovery time is recorded with natural aging for two months, showing acceptable long-term durability. The mechanism by which the responsivity of S-BSi-based sensors varies with resistivity is discussed. Based on this mechanism, there is an optimal substrate resistivity that maximizes the responsivity. The results show that S-BSi is a potential material for the fabrication of conductivity gas sensor with good NH3 detection performance.

Aluminizing as a method of improvement of Mar-M247 alloy lifetime

Environmentally friendly high temperature high-activity (HTHA) and high temperature low- activity (HTLA) CVD aluminizing processes were realized on the Mar-M247 heat resistant superalloy substrate that is widely used in the hot section of aircraft engines. Additionally, commercial aluminide coatings deposited in the above-the-pack aluminiznig process were analyzed. The aluminizing of the Mar-M247 superalloy by the HTHA, HTLA and above-the-pack processes led to formation of two layers of the coatings. The outer layer of the coatings formed by the above-the-pack process consisted of the ?-NiAl phase with precipitates, while the outer layer of coatings formed by the HTHA and HTLA processes consisted of the pure ?-NiAl phase. Aluminizing successfully improved the lifetime of Mar-M247 superalloy. Despite the fact that the coatings formed by the above-the-pack process are thicker and have a higher aluminium concentration than the coatings formed by the HTLA aluminizing and process, the lifetime of the coated superalloy was lower. Moreover the oxidation resistance of the coated superalloy in the HTLA aluminizing process was better than that of the coating in the HTHA aluminizing process. The removal of impurities in the HTLA aluminizing process ensured a ?pure? outer layer of the coatings. Clean aluminide coatings may create a purer alumina oxide and may prolong its lifetime.

(Electrodeposition Division Research Award) Electrodeposition as an Enabling Technology in Future Semiconductors, Energy Storage, and Sustainable Metal Production

Electrodeposition is a truly fascinating process. On the one hand, it is highly complex as it entails a myriad of intricately intertwined physiochemical events (transport, kinetics, nucleation, growth, to name a few). Despite this, to a practitioner, electrodeposition can be remarkably simple, easy to control, and safe to operate. Electrodeposition is also extremely versatile, enabling fabrication of various materials (metals, alloys, semiconductors), fabrication onto conductive or resistive substrates, facilitating intricate pattern formation, and providing selectivity in growth. These advantages make electrodeposition a process of choice in a broad range of technologically-important applications: batteries, semiconductor devices, electrometallurgy, and others.1-3 Morphology control is crucial in the industrial practice of electrodeposition. During metallization of nano-scale interconnects in advanced semiconductor devices, metal deposition with near atomic precision is required.1 Similarly, during operation of lithium metal rechargeable batteries, electrodeposition must be controlled to avoid dendritic growth during battery charging.2 Electrodeposition processes in high temperature molten salts, such as those used for electrowinning rare-earth metals, favor spongy deposits which can manifest in entrapment of impurities – here too, controlling morphology is central to overall electrowinning efficacy.3 In this talk, I will discuss and demonstrate how unprecedented morphology control can be achieved in electrodeposition. Such control leverages fundamental understanding of the electrochemical processes at the electrode-electrolyte interface. Specifically, by regulating the electrolyte properties, applied current or potential waveforms, and by employing ‘additives’, the diffusion-reaction processes can be controlled yielding desirable electrodeposit morphologies. Such design of electrodeposition processes is considerably aided by mathematical modeling. I will provide a few examples of how quantitative modeling enables improved process designs in aforementioned applications.During my odyssey in electrodeposition since 2001, I have been fortunate to have exceptional colleagues, collaborators, sponsors, mentors, students and friends, who have made this journey enjoyable and enriching. I am also very thankful for my affiliation to the Electrochemical Society and its electrodeposition division. In my talk, I will provide a few perspectives and anecdotes on how the ECS community has positively impacted me personally and professionally.

(Invited) Electrochemical Deposition for Applications in the Semiconductor Industry

This year (2023) marks the 25th anniversary of the “Damascene copper electroplating for chip interconnections” publication by P.C. Andricacos et al [1] detailing the dual-damascene process and Cu superfilling of complex structures. And even though this was neither the only electrochemistry contribution to the semiconductor industry nor the first time to report successful plating of Cu structures, it signaled that electrochemical deposition would play prominent role in downscaling race [2]. The authors described Cu superfilling of a feature having characteristic dimensions of about 1 micron. Since then, electrochemists have focused intensely on electrolyte development, optimization of deposition parameters, and improvements in plating tools and process chambers, which went hand in hand with downscaling of features to be filled. Cu was plated on resistive substrates and alternative seeds, various surface pretreatments were applied, and nucleation and growth phenomena studied [3-6], until the focus shifted to alternative metals, such as Co [7]. While Chemical vapor deposition (CVD) and Atomic layer deposition (ALD) offer viable alternatives to electrochemical deposition (ECD) in fabrication of interconnects having width of several nanometers, new challenges and opportunities in 3D packaging and stacking appeared on the horizon. This field resembles more a ‘landscape’ than a ‘one-way street’ that damascene nano-interconnects were. While on one hand downscaling is gaining momentum here, too, there is also upscaling. For example, electrochemically deposited mega-pillars have diameters and heights exceeding hundreds of microns. More than a decade ago, a competitive race started between chemistry suppliers, tool manufacturers and scientists in the field to achieve bottom-up Cu fill of through-Si-vias (TSV) [8], structures meant to provide interconnections between vertically stacked integrated circuits. These structures had characteristic sizes an order of magnitude larger than the ones described in [1]. After demonstrating that superfilling of TSV was indeed possible, it became imperative to satisfy a plethora of production-line requirements, such as optimization of plating time or control of the so-called Cu pumping, a plastic deformation of Cu upon annealing. Plastic deformation leads to an uneven top surface and challenges in stacking layers on top of each other and is, therefore, undesirable. Today, researchers are contemplating possible benefits of the plastic deformation in Cu structures to establish a more robust and reliable Cu-to-Cu bonding process. Achieving defect-free fill of features was never the only requirement to be satisfied, but the ability to control plastic deformation in Cu features, or fabricate structures with specific texture, grain size, crystal structure [9, 10] on sub-micron scale, might require more thorough modifications of the current Cu plating processes. We will review this and other current trends in electrochemical deposition for applications in ‘classical’ semiconductor industry. We will also consider possibilities in technologies for Quantum computing, where a new spectrum of non-traditional candidate elements for plating could emerge [11, 12]. There, lessons learned from the downscaling of traditional interconnects could prove very useful.

High powered output flexible aerogel triboelectric nanogenerator under ultrahigh temperature condition

Triboelectric nanogenerators (TENGs) have emerged as promising devices for harvesting low-frequency energy, but its application in high-temperature environments is limited. In this article, a flexible high-temperature resistant fiber substrate material was developed using needled felt and silicon aerogel. This material demonstrated exceptional resistance, withstanding exposure to a butane flame at approximately 1300 ℃ for a minimum of 10 min without experiencing burn-through. Following the application of electrodes and protective encapsulating, a high-temperature resistant silicon aerogel and fiber felts based triboelectric nanogenerator (HTFs-TENG) was successfully created. In addition, we achieved remarkable enhancements in the electrical output performance of the HTFs-TENG by precisely regulating its dielectric properties, resulting in an impressive increase in peak voltage from 17 V to 135 V. The current output increased from 1.4 μA to 6 μA. The HTFs-TENG demonstrated remarkable adaptability, operating effectively at temperatures as high as 275 ℃ and as low as approximately − 75 ℃. Moreover, it showcased an instantaneous power density output of 31.9 mW/m2 under a 100 MΩ resistance load. The HTFs-TENG displayed impressive electrical signal response capabilities at ultralow frequencies (≤1 Hz) across various temperatures and frequencies, positioning it as an ideal self-powered vibration sensor and temperature sensor for diverse generator applications.