电沉积Mo和Mo-Co合金纳米线用于互联电阻的电阻率改性

Achieving historically anticipated improvement in the performance of integrated circuits is challenging,due to the increasing cost and complexity of the required technologies with each new generation.To overcome this limitation,the exploration and development of novel interconnect materials and processes are highly desirable in the microelectronics field.Molybdenum(Mo)is attracting attention as an advanced interconnect material due to its small resistivity size effect and high cohesive energy;however,effective processing methods for such materials have not been widely investigated.Here,we investigate the electrochemical behavior of ions in the confined nanopores that affect the electrical properties and microstructures of nanoscale Mo and Mo-Co alloys prepared via template-assisted electrodeposition.Additives in an electrolyte allow the deposition of extremely pure metal materials,due to their interac-tion with metal ions and nanopores.In this study,boric acid and tetrabutylammonium bisulfate(TBA)were added to an acetate bath to inhibit the hydrogen evolution reaction.TBA accelerated the reduction of Mo at the surface by inducing surface conduction on the nanopores.Metallic Mo nanowires with a 130 nm diameter synthesized through high-aspect-ratio nanopore engineering exhibited a resistivity of(63.0±17.9)μΩcm.We also evaluated the resistivities of Mo-Co alloy nanowires at various compo-sitions toward replacing irreducible conventional barrier/liner layers.An intermetallic compound formed at a Mo composition of 28.6 at%,the resistivity of the Mo-Co nanowire was(58.0±10.6)μΩcm,indicat-ing its superior electrical and adhesive properties in comparison with those of conventional barriers such as TaN and TiN.Furthermore,density functional theory and non-equilibrium Green's function calcula-tions confirmed that the vertical resistance of the via structure constructed from Mo-based materials was 21%lower than that of a conventional Cu/Ta/TaN structure.

Isothermal hydrogen absorption process of Pd-capped Mg films traced by ion beam techniques and optical methods

Pd-capped nanocrystalline Mg films were prepared by electron beam evaporation and hydrogenated under isothermal conditions to inves-tigate the hydrogen absorption process via ion beam techniques and in situ optical methods.Films were characterized by different techniques such as X-ray diffraction(XRD)and scanning electron microscopy(SEM).Rutherford backscattering spectrometry(RBS)and elastic recoil detection analysis(ERDA)provided a detailed compositional depth profile of the films during hydrogenation.Gas-solid reaction kinetics theory applied to ERDA data revealed a H absorption mechanism controlled by H diffusion.This rate-limiting step was also confirmed by XRD measurements.The diffusion coefficient(D)was also determined via RBS and ERDA,with a value of(1.1±0.1)·10^(−13)cm^(2)/s at 140℃.Results confirm the validity of IBA to monitor the hydrogenation process and to extract the control mechanism of the process.The H kinetic information given by optical methods is strongly influenced by the optical absorption of the magnesium layer,revealing that thinner films are needed to extract further and reliable information from that technique.

Long cycle-life aqueous Zn battery enabled by facile carbon nanotube coating on Cu current collector

As an alternative to Li-ion batteries,aqueous Zn batteries have gained attention due to the abundance of Zn metal,low reduction potential(-0.76 V vs.standard hydrogen electrode),and high theoretical capacity(820 mAh g^(-1))of multivalent Zn2+ion.However,the growth of Zn dendrites and the formation of irreversible surface reaction byproducts pose challenges for ensuring a long battery lifespan and commercialization.Herein,the Cu foil coated with a single-walled carbon nanotube(SWCNT)layer using a facile doctor blade casting method is utilized.The SWCNT-coated Cu foil demonstrates a significantly longer battery lifespan compared to the bare Cu in the half-cell tests.Through operando optical microscopy imaging,we are able to provide intuitive evidence that Zn deposition occurs between the carbon nanotube(CNT)coating and Cu substrate,in agreement with the computational results.Also,with various imaging techniques,the flat morphology and homogeneous distribution of Zn beneath the SWCNT layer are demonstrated.In addition,the full-cell using CNT-coated Cu exhibits a long cycle life compared to the control group,thereby demonstrating improved electrochemical performance with limited Zn for the cycling process.

Toward a comprehensive hypothesis of oxygen-evolution reaction in the presence of iron and gold

This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the second with Au sites at high overpotential(~870 mV).Various factors such as surface Fe concentration,electrochemical method,scan rate,potential range,concentration,method of adding K_(2)Fe O_(4),nature of Fe,and temperature were varied to observe diverse behaviors during OER for Fe O_(x)H_(y)/Au.Trace amounts of Fe ions had a significant impact on OER,reaching a saturation point where the activity did not increase further.Strong electronic interaction between Fe and Au ions was indicated by X-ray photoelectron spectroscopy(XPS)and electron paramagnetic resonance(EPR)analyses.In situ visible spectroscopy confirmed the formation of Fe O_(4)^(2-)during OER.In situ Mossbauer and surfaceenhanced Raman spectroscopy(SERS)analyses suggest the involvement of Fe-based species as intermediates during the rate-determining step of OER.A lattice OER mechanism based on Fe O_(x)H_(y)was proposed for operation at low overpotentials.Density functional theory(DFT)calculations revealed that Fe oxide,Fe-oxide clusters,and Fe doping on the Au foil exhibited different activities and stabilities during OER.The study provides insights into the interplay between Fe and Au in OER,advancing the understanding of OER mechanisms and offering implications for the design of efficient electrocatalytic systems.

High-performance photoelectrochemical cells with MoS2 nanoflakes/TiO2 photoanode on 3D porous carbon spun fabric

A solar-driven photoelectrochemical(PEC)cell is emerging as one of the promising clean hydrogen generation systems.Engineering of semiconductor heterojunctions and surface morphologies of photoelectrodes in a PEC cell has been a primitive approach to boost its performance.This study presents that a molybdenum disulfide(MoS_(2))nanoflakes photoanode on 3-dimensional(3D)porous carbon spun fabric(CSF)as a substrate effectively enhances hydrogen generations due to sufficiently enlarged surface area.MoS_(2)is grown on CSFs utilizing a hydrothermal method.Among three different MoS_(2)coating morphologies depending on the amount of MoS_(2)precursor and hydrothermal growth time,film shape MoS_(2)on CSFs had the largest surface area,exhibiting the highest photocurrent density of 26.48 mA/cm^(2)and the highest applied bias photon-to-current efficiency(ABPE)efficiency of 5.32%at 0.43 VRHE.Furthermore,with a two-step growth method of sputtering and a subsequent hydrothermal coating,continuous TiO_(2)/MoS_(20 heterojunctions on a porous CSF further promoted the photoelectrochemical performances due to their optimized bandgap alignments.Enlarged surface area,enhanced charge transfer,and utilization of visible light enable a highly efficient MoS_(2)/TiO_(2)/CSF photoanode with a photocurrent density of 33.81 mA/cm^(2)and an ABPE of 6.97%at 0.87 VRHE.The hydrogen generation amount of the PEC cell with MoS_(2)/TiO_(2)/CSF photoanode is 225.4μmol/L after light irradiation of 60 s.

Effects of Cr doping on structural and electrochemical properties of Li_(4)Ti_(5)O_(12) nanostructure for sodium-ion battery anode

Sodium-ion batteries are considered as promising alternatives to lithium-ion batteries,owing to their low cost and abundant raw materials.Among the several candidate materials for the anode,spinel-type Li_(4)Ti_(5)O_(12)has potential owing to its superior safety originating from an appropriate operating voltage and the reversible Na^(+)intercalation properties.However,a low diffusion coefficient for Na^(+)and the insulating nature of LTO remains challenging for practical sodium-ion battery systems.Herein,we present a strategy for integrating physical and chemical approaches to achieve superior electrochemical properties in LTO.We demonstrate that carefully controlling the amount of Cr doping is crucial to enhance the electrochemical properties of nanostructured LTO.Optimized Cr doped LTO shows a superior reversible capacity of 110 m Ah g^(-1) after 400 cycles at 1 C,with a three-fold higher capacity(75 m Ah g^(-1))at 10 C compared with undoped LTO material.This suggests that appropriately Cr doped nanostructured LTO is a promising anode material for sodium-ion batteries.

Paleo-shoreline changes in moraine dammed lake Khagiin Khar, Khentey Mountains, Central Mongolia

The formation and evolution of glacier moraine-dammed lakes are closely related to past glacier expansion and retreat. Geomorphic markers such as lacustrine terraces and beach ridges observed in these lakes provide important evidence for regional paleoenvironment reconstruction. We document the magnitude of paleo-shoreline fluctuations and timings of highstands of lake water by using cosmogenic 10Be surface exposure dating and optically stimulated luminescence(OSL) dating on samples collected from lacustrine sediment and bedrock strath in Lake Khagiin Khar. The lake was initially impounded by glacier moraine at the Global Last Glacial maximum(gLGM;21–19 ka), and the lake reached its maximum paleo-shoreline level of 1840 m at sea level(a.s.l.). At that time, the stored lake water amount was up to seven times greater and the surface area was three times larger than the present values. The paleolake experienced higher shoreline levels at 1832, 1822, and 1817 m a.s.l. and reached the present lake level after 0.4 ka. We interpret that decrease in the paleolake level was caused by spillover. The increase in melt water after the gLGM and the Late Glacial exceeded the storage threshold of the lake, and the paleolake water overflowed across the lowest drainage divides. The lake spilled over across the lowest bedrock ridge at 15.9 ± 0.6 ka, and the outlet was incised since that time at a rate of 3.72 ± 0.15 mm/yr. The initial stream of the Khiidiin Pass River was disturbed by LGM moraine damming and was rerouted into the present course running through moraine after the spillover at 15.9 ± 0.6 ka.

Focused-Ion-Beam Induced Paramagnetic Defects in FAMn:PbI3 Perovskite Films

FAMn:PbI3 perovskite films were synthesized and probed mainly through electron spin resonance (ESR) spectroscopy. FAMn:PbI3 with low (~1%) Mn concentration showed a hyperfine sextet line originated from Mn++ ions. FAMn:PbI3 with high (10%) Mn concentration showed broad resonance (~500 G peak-to-peak linewidth). However, after bombardment of FAMn:PbI3 with high Mn concentration by focused ion beams (FIB), a sharp ESR peak appeared. The peak-to-peak linewidth (ΔHpp) was ~8 G regardless of the temperature. The FIB-induced defect showed Curie behavior at low temperatures (5 K - 50 K), which indicates the presence of localized electrons at the defect sites at low temperatures. The g-value increased from g = 2.0002 to 2.0016 as the temperature increased from 5 K to 50 K. Together with the ongoing search for electron spin echo (ESE), this could potentially provide a platform for realizing magnetic bits, information storage, and increased manipulation speed.

Quantitative detection of citrate for early stage diagnosing of prostate cancer:Discriminating normal to cancer in prostate tissues

Prostate cancer(PC)biomarker-citrate detection is clinically important to diagnose PC in early stages.Methylquinolinium iodide(Q)conjugated indole-phenylboronic acid(IB)was designed as a red-emissive QIB probe for the detection of citrate through Lewis acid-base reaction and intramolecular charge transfer(ICT)sensing mechanisms.Boronic acid acts as Lewis acid as well as citrate(Lewis base)recognition unit.The probe reacted with citrate,showing enhanced red emissions.Since the probe has excellent water solubility and great biocompatibility,practical application in biological systems is possible.Citrate was monitored precisely in the mitochondria organelle(in vitro)of living cells with a positive charge on QIB.Also,endogenous(in situ)citrate was detected quantitatively to discriminate non-cancerous and PC mice,observed strong and lower(negligible)emission intensity on non-cancerous and cancerous prostate tissues,respectively.Because,the concentration of citrate is higher in healthy prostate compared with PC prostate.Furthermore,the analysis of sliced prostate tissues can give PC-related information for clinical diagnosis to prevent and treat PC in the initial stages.Therefore,we believe that the present probe is a promising biochemical reagent in diagnosing PC.

High‑Performance Thick Cathode Based on Polyhydroxyalkanoate Binder for Li Metal Batteries

Thick cathodes can overcome the low capacity issues,which mostly hamper the performance of the conventional active cathode materials,used in rechargeable Li batteries.However,the typical slurry-based method induces cracking and flaking during the fabrication of thick electrodes.In addition,a significant increase in the charge-transfer resistance and local cur-rent overload results in poor rate capabilities and cycling stabilities,thereby limiting electrode thickening.In this study,a synergistic dual-network combination strategy based on a conductive nanofibrillar network(CNN)and a nano-bridging amor-phous polyhydroxyalkanoate(aPHA)binder is used to demonstrate the feasibility of constructing a high-performance thick cathode.The CNN and aPHA dual network facilitates the fabrication of a thick cathode(≥250μm thickness and≥90 wt%active cathode material)by a mass-producible slurry method.The thick cathode exhibited a high rate capability and excel-lent cycling stability.In addition,the thick cathode and thin Li metal anode pair(Li//t-NCM)exhibited an optimal energy performance,affording high-performance Li metal batteries with a high areal energy of~25.3 mW h cm^(-2),a high volumetric power density of~1720 W L^(-1),and an outstanding specific energy of~470 W h kg^(-1)at only 6 mA h cm^(-2).

Effect of tellurium on the microstructure and mechanical properties of Fe-14Cr oxide-dispersion-strengthened steels produced by additive manufacturing

Conventionally,Te has primarily been used to improve the machinability of steel and its alloys.In this work,Te was used to refine the grains of an oxide-dispersion-strengthened(ODS)steel produced by additive manufacturing(AM)with fixed processing parameters.Addition of Te to the raw powder produced an ODS steel with a fine-grained microstructure,in contrast to the ODS steel manufactured without Te.Moreover,the addition of Te resulted in superior yield strength and ultimate tensile strength,which was attributed to the combined effects of grain refinement and the finer nanoparticles(NPs)composed of Terich composite NPs and Cr-rich NPs.For the first time,the AM technique was used to obtain grain and nanoparticle sizes of~3.4μm and 6 nm,respectively,from the Te-added ODS steel.

Effect of Sub-T_g Annealing on the Corrosion Resistance of the Cu–Zr Amorphous Alloys

Despite the economy of material cost and excellent toughness of Cu-based amorphous alloys,especially CusoZrso,their poor corrosion resistance to a chloride medium limits their widespread applications.In this study,corrosion tests were performed on the CusoZrso amorphous alloy with different degrees of short-range order,which were prepared by annealing below the glass transition temperature（Tg）.It was found that the corrosion resistance of amorphous alloys is improved to a significant level when the alloys were heated below Tg.Calorimetric studies showed that thermally activated relaxation process of created disorder,which occurs during sub-Tg annealing,is responsible for the improvement in the corrosion resistance.Molecular dynamics simulations performed on the Cu-Zr amorphous alloys demonstrated that the relaxation process of the alloys is associated with the formation of energetically stable icosahedra and icosahedron-like structures.Our study highlights the effects of sub-Tg annealing on the improvement in the corrosion resistance of the amorphous alloys from the viewpoint the relaxation process of the short-range orders.

Electrical resistivity evolution in electrodeposited Ru and Ru-Co nanowires

Nanoscale ruthenium(Ru)-based materials are promising replacements for existing multilayered Cu interconnects in integrated circuits.However,it is not easy to apply the results of previously reported studies directly to the electrochemical damascene process because the previous studies have mainly focused on thin flms by dry deposition.Here,we report the electrical resistivity and microstructure of electrodeposited Ru nanowires.We estimate that the resistivity value of a 10 nm diameter Ru nanowire to be71.6μΩcm after analyzing the resistivity values of individual nanowires with various diameters.Furthermore,we investigate the electrical properties of Ru_(x)Co_(1-x)nanowires where x is 0.04–0.99 at.%as possible replacements of the current Ta N barrier structures.Over the entire composition range,the resistivity values of alloys are much lower than that of the conventional Ta N.Additionally,Ru and Ru-alloy nanowires surrounded by dielectric silica are thermally stable after 450°C heat treatment.Therefore,the nanoscale Ru and Ru-Co alloys possessing low resistivity values can be candidates for the interconnect and barrier materials,respectively.

High-throughput computational-experimental screening protocol for the discovery of bimetallic catalysts

To accelerate the discovery of materials through computations and experiments,a well-established protocol closely bridging these methods is required.We introduce a high-throughput screening protocol for the discovery of bimetallic catalysts that replace palladium(Pd),where the similarities in the electronic density of states patterns were employed as a screening descriptor.Using first-principles calculations,we screened 4350 bimetallic alloy structures and proposed eight candidates expected to have catalytic performance comparable to that of Pd.Our experiments demonstrate that four bimetallic catalysts indeed exhibit catalytic properties comparable to those of Pd.Moreover,we discover a bimetallic(Ni-Pt)catalyst that has not yet been reported for H_(2)O_(2) direct synthesis.In particular,Ni_(61)Pt_(39) outperforms the prototypical Pd catalyst for the chemical reaction and exhibits a 9.5-fold enhancement in cost-normalized productivity.This protocol provides an opportunity for the catalyst discovery for the replacement or reduction in the use of the platinum-group metals.

Cu2O nanocrystals with various morphology:Synthesis,characterization and catalytic properties

Cu2O nanocubes,octahedra,spheres and truncated rhombic dodecahedral were prepared and their structural,morphological,and electronic properties were investigated by X-ray diffraction analysis.X-ray absorption near edge structure,scanning electron microscope and transmission electron microscope and X-ray absorption near edge structure.Cu2O nanocrystals were successfully employed to catalyze the 1,3-dipolar cycloaddition reaction for the synthesis of 1,4-disubstituted triazoles.Cu2O nanocubes and octahedral showed the superior catalytic performance in the cycloaddition reaction.These results reveal that crystal-plane engineering of oxide catalysts is a useful strategy for developing efficient catalysts for organic reaction.

Materialization of strained CVD-graphene using thermal mismatch

Theoretical physics foretells that ＂strain engineering＂ of graphene could hold the key to finding treasures still hidden in two-dimensional （2D） condensed matter physics and commercializing graphene-based devices. However, to produce strained graphene in large quantities is not an easy task by any means. Here, we demonstrate that thermal annealing of graphene placed on various substrates could be a surprisingly simple method for preparing strained graphene with a large area. We found that enhanced graphene-substrate interfacial adhesion plays a critical role in developing strained graphene. Creative device architectures that consider the thermal mismatch between graphene and the target substrate could enable the resulting strain to be intentionally tailored. We believe that our proposed method could suggest a shortcut to realization of graphene straintronics.

Effect of precursor thermal history on the formation of amorphous and crystalline calcium carbonate

The role of the thermal history of the precursor was studied for amorphous and crystalline calcium carbon- ate phases synthesized from calcium nitrate. The X-ray diffraction patterns of these phases are influenced by their annealing temperature of 0, 300, 400, and 500 ℃. However, the effect of the precursor thermal history on the X-ray diffraction pattern of the resulting calcium carbonate phase is negligible. Transmis- sion electron microscopy indicates that materials annealed at 400 ℃ consist of amorphous aggregates, irrespective of the precursor thermal history. The crystallite size of crystalline calcium carbonate is influ- enced by the precursor thermal history, and ranges from 23 to 26 rim. Near-edge X-ray absorption fine structure measurements indicate that the annealing temperature plays an important role in determining the local electronic structure. The role of the thermal history of the precursor is also important for the resultinu electronic structure.