bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion Behavior of High Pressure Die Cast Al Alloys in Neutral and Acidic 3.5 Wt.% NaCl Solutions
Authors: Jun Jiheon , Shyam Amit , Bahl Sumit , Su Yi-Feng , Richter Nicholas , Haynes J. Allen
Published: December 2024

High Pressure Die Cast (HPDC) Al alloys are of interest as automotive structural materials. Owing to the unique processing conditions, HPDC Al alloys may exhibit distinct microstructures compared to other cast automotive Al alloys. In this work, we are evaluating corrosion behavior of several HDPC Al alloys with varied chemical compositions in comparison with non-HPDC commercial Al cast alloy(s) using electrochemical impedance and polarization techniques, and long-term exposure sample characterization in typical 3.5 wt.% NaCl with and without HCl addition to lower pH. A lower pH NaCl solution is used to increase the frequency of corrosion attack growth for collection of statistical corrosion depth data. The key results will be discussed to allow semi-quantitative comparison of HPDC Al alloy resistance against corrosion initiation and growth.
Materials and Device Engineering for Non-Halogenated Solvent-Processed Organic Solar Cells
Authors: Song Chang Eun
Published: December 2024

Organic solar cells (OSCs), known as a promising technology for harnessing solar energy, have garnered substantial attention from academia and industry owing to their semitransparency, flexibility, low cost, and large-area printability. Advancements in the design and synthesis of photoactive materials, coupled with progress in device engineering and photophysics have propelled single-junction OSCs surpassing 19% power conversion efficiency (PCE). Meanwhile, the conventional choice for processing solvents in the construction of high-efficiency OSCs includes halogenated solvents like chloroform and chlorobenzene. These solvents exhibit exceptional solubility in the highly conjugated and fused structures of photoactive materials. Despite their substantial PCEs, these solvents pose significant environmental and health risks, making them unsuitable for large-scale OSC fabrication; thus, developing photoactive material processing methods using halogen-free solvents is widely acknowledged as a strategic processing solution. In this presentation, I will discuss the materials and device engineering in non-halogenated solvent-processed OSCs for excellent device efficiency and operational stability.
Ultrastretchable Photovoltaics with High Areal Coverage Using a 3D Printer-Based Kirigami/Origami Technique
Authors: Lee Phillip
Published: December 2024

The elasticity and surface coverage of active components are pivotal aspects for making photovoltaic devices stretchable or wearable. However, in conventional two-dimensional manufacturing methods, it's challenging to optimize both properties simultaneously due to their intrinsic interdependence. Here, we introduce an ultra-stretchable structure based on 3D printing, boasting extensive surface coverage. Crafting flexible and resilient conductive frameworks via 3D printing poses challenges owing to inherent trade-offs. Employing an axiomatic approach to embed a network of two-dimensional silver nanowires onto the surfaces of flexible 3D-printed structures provides ample conductivity and malleability for integration into stretchable energy conversion systems. Achieving high stretchability and surface coverage is made possible through a three-dimensional arrangement of interconnects inspired by kirigami/origami techniques, capitalizing on the design flexibility inherent in 3D printing technologies. This proposed method facilitates the creation of perovskite solar modules with a system stretchability of 400%, interconnect stretchability of 25,000%, and approximately 97% surface coverage. This 3D printing approach, with its potential for cost-effectiveness, scalability, and rapid production, lays the groundwork for future advancements in energy conversion technologies.
Dithienopyran-Based Narrow-Bandgap Donor Polymers: Unveiling the Potential for Semitransparent Organic Solar Cells with Enhanced NIR Absorption
Authors: Ryu Seung Un , Park Taiho
Published: December 2024

Semitransparent organic solar cells (ST-OSCs) have recently received considerable attention in the field of photovoltaics owing to their great potential in applications such as building-integrated photovoltaics, self-powered greenhouses, and vehicle coatings. Because the near-infrared (NIR) region is an invisible region whose photon content is higher than that of the visible region, it is preferable to apply photoactive materials with narrow bandgaps in ST-OSCs. Tremendous efforts have been made to develop narrow-bandgap non-fullerene acceptors, however, donor polymers with NIR absorption ability for efficient ST-OSCs have rarely been reported. In this study, two novel narrow-bandgap donor polymers, PDTP-TBT and PDTTP-TBT, are designed and synthesized. Both polymers exhibit strong NIR absorption and high transmittance in the visible region, suggesting their potential for use in ST-OSCs. An opaque OSC with a PDTTP-TBT-based photoactive layer achieves a higher power conversion efficiency (PCE) of 8.87% than a PDTP-TBT-based OSC (PCE of 3.65%) due to its better charge transport characteristics. Furthermore, an ST-OSC using PDTTP-TBT-based blend film exhibits a PCE of 6.72%, average visible transmittance of 43.9%, and light utilization efficiency of 2.95%.
Patterning of Sin and SiO2 Nanostructures for 3D Electronic Devices at Low Temperatures
Authors: Lill Thorsten , Barsukov Yuri , Oh Youn-Jin , Kaganowich Igor , Singh Harmeet
Published: December 2024

Silicon oxide, SiO2, and silicon nitride, SiN, are widely used in memory and logic devices because of their dielectric properties, compatibility with silicon-based devices and etching selectivity. Advanced electronic devices are integrated increasingly in vertical direction, and critical etching challenges must be addressed to advance the technology roadmap. Among the enabling applications are vertical etching of SiO2 and SiN with high aspect ratio as well as lateral or isotropic etching of these films with high selectivity. Hydrofluoric acid gas has been used for over 30 years for isotropic etch of SiO2 (1, 2). The process has many similarities with wet etching using HF and requires the presence of water at the surface. Gas-phase etching of silicon nitride films has been demonstrated using moist HF vapor followed by heating of the wafer to remove ammonium fluorosilicate (NH4)2SiF6 or AFS as an intermediate reaction product (3). Recently, HF is used in high aspect ratio plasma etching of SiO2, SiN and multilayer stacks of these films at wafer temperatures below room temperatures (4). The elementary reactions bare resemblance with the vapor etch analogues. In this paper, we will present experimental results on plasma and vapor etching of SiO2 and SiN. The underlaying etching mechanisms will be explained using molecular dynamics and density functional theory.

References:

Miki, H. Kikuyama, I. Kawanabe, M. Miyashita, T. Ohmi, IEEE Transactions on Electron Devices 37, 107 (1990).

R. Helms, B. E. Deal, J. Vac. Sci. Technol. A 10, 806 (1992).

Vereecke, M. Schaekers, K. Verstraete, S. Arnauts, M. M. Heyns, W. Plante, J. Electrochem. Soc. 147, 1499 (2000).

Kihara, M. Tomura, W. Sakamoto, M. Honda, M. Kojima, 2023 IEEE Symposium on VLSI Technology and Circuits (VLSI Technology and Circuits)
, Kyoto, Japan, 2023, pp. 1-2
Hard Carbon Sodiation and Its Mechanical Impact on Formation
Authors: Owen Christopher , Thorsteinsson Gunnar , Steingart Daniel A.
Published: December 2024

Acoustic waves can assess the wetting extent of a porous material by sending sound waves through the material and analyzing how those waves are reflected, refracted, or absorbed. Using modeling and analytical tools developed by the seismology community and correlating with traditional impedance measurements, we have shown that the wetting extent can be understood for many cycles. In this study, we determine where and when the electrolyte moves during Na-ion formation. Further, we discuss how the SEI varies as a function of the adsorption, intercalation, and pore-filling modes of sodium storage observed by the community in hard carbon electrodes.
Enhancing Cesium Cation Exchange Efficiency Using Transition Metal-Based Core-Shell Prussian Blue Analogue-Carbon Nanofiber Composites
Authors: Kim Minsun , Kim Soonhyun , Eun Semin
Published: December 2024

Electrochemical cation exchange processes are vital for diverse applications, including energy storage, catalysis, and environmental remediation. However, enhancing the efficiency of cation exchange with novel materials remains a challenge. Prussian blue (PB) is well-known to its excellent cation exchange properties, but improving its performance is necessary. To solve these problems, the use of various supporting matrices attach to PBA colloids has been reported such as zeolite, silica or carbon-based materials. In light of this, carbon-supported materials are particularly effective due to their unique microstructure and chemical stability, enabling rapid electron transfer. Among potential solutions, core-shell structured composites present a promising approach for enhancing electrochemical properties due to their unique architecture and synergistic effects.

In this study, we propose a method for synthesizing core-shell structured Prussian blue analogue-carbon nanofiber (PBA-CNF) composites using various transition metals (Fe, Ni, Co, Cu, Mn) via electrodeposition and evaluated their effectiveness in cesium cation exchange via electrochemical adsorption/desorption processes. The prepared samples are characterized using SEM, TEM, and XRD measurements. Electrochemical characterization confirmed distinct adsorption and desorption behaviors for each transition metal-based composite. In particular, Fe, Ni, and Cu-based PBA-CNF composites exhibited enhanced efficiency in both cesium adsorption and desorption compared to other PBA-CNF composites. This suggests the potential for effectively removing cesium from contaminated water sources. This study highlights the significance of transition metal-based PBA composites in resolving challenges associated with cesium contamination through electrochemical applications
(Invited) Room Temperature Electrochemical Synthesis of Ordered Intermetallic Catalysts
Authors: Hall Shoji
Published: December 2024

The development of efficient renewable energy conversion and storage devices is one of the most important challenges of the 21st century. Fuel cell catalysis, CO2 reduction, etc. are promising reactions for transforming our energy economy. However, many of these reactions are sluggish from unfavorable reaction kinetics and poor product selectivity. Ordered intermetallic compounds (OIC) can exhibit enhanced performance and selectivity for mediating electrochemical reactions relative to solid-solution alloys. However, OIC often require high temperature and pressure to synthesize, resulting in poor control of the morphology. Furthermore, high temperature processing can cause the formation of impurity phases from reactions with the support material. This talk will discuss our efforts on the synthesis, stability, and catalytic activity of OICs prepared by electrochemical methods at room temperature and atmospheric pressure. Developing methods for preparing OIC compounds under ambient conditions is essential for designing catalysts for the next generation of renewable energy devices.
Effect of Local pH Change on Galvanostatic Deposition of n-Type Cu2o in Acidic Media: A Chronopotentiometry Study
Authors: Lakra Kabita , Balasubramaniam Kavaipatti
Published: December 2024

N-type cuprous oxides (Cu2O) were electrodeposited on Fluorine-doped Tin Oxide (FTO) coated glass substrate in acidic media. We investigated the chrono-potentiometry behavior of the deposited Cu2O films across various current densities. Lower current densities exhibited stable potentials, while higher densities resulted in sharp spikes followed by stabilization. Notably, our study in an acidic medium did not manifest potential oscillations typically observed in alkaline systems. Remarkably, we observed negative potential spikes in the chronopotentiometry curve, particularly at higher current densities exceeding -0.2 mA cm-2, which remains a highlight of our findings. The potential spike indicates the likelihood of a second reaction, the formation of Cu. We argue that the formation of Cu originates from the reduction of Cu2O rather than bulk deposition, primarily due to the change in local pH near the working electrode during the Cu2O deposition process. Continuous stirring of the electrolyte aids in delaying the Cu2O to Cu conversion reaction (Cu2O corrosion), with further influence observed by altering the rotation speed during stirring. Unlike the well-explored galvanostatic deposition of Cu2O in basic media, the behavior of such deposition in acidic media remains largely unexplored. Our study provides insights into the formation of phase-pure n-type Cu2O and obviates the occurrence of the speculated second reaction, Cu2O corrosion. Phase-pure n-type Cu2O enables investigations into defect chemistry governing n-type behavior without metallic Cu complications. It serves as an electron transport layer in photo-conversion devices and allows for homojunction devices with p-type Cu2O.

Figure 1
Reactive Force Field for Atomistic Understanding of Interfacial Processes in Sulfide Electrolytes
Authors: Shreyas Varun , Jaishi Meghnath , Narayanan Badri
Published: December 2024

All solid-state lithium-metal batteries (ASSLMBs) using sulfide electrolytes offer tremendous promise due to their increased safety and high theoretical specific capacity. Lithium argyrodites have emerged as a lucrative class of solid-state electrolytes (SSEs) for ASSMLBs, owing to their high Li-ion conductivity (~10-4–10-3 S/cm), good elastic stiffness (~30 GPa), and low flammability. The Li-ion conduction pathways in single-crystalline compounds are typically examined using ab initio molecular dynamics (AIMD) simulations. However, the real-world materials have an added complexity of accounting for grain boundaries (GBs), which makes the AIMD simulations computationally expensive. To circumvent this limitation, we developed a novel ReaxFF interatomic potential, an empirical bond-order based force field, to investigate the effect of GBs on the Li-ion conductivity in argyrodite electrolytes. To carry out the fitting procedure, we used the fundamental static properties such as lattice parameters, heats of formation, elastic constants, surface energies, and equation of states in order to find the best set of ReaxFF parameters for LiPS system. All the static properties used in the fitting process were calculated using the periodic density functional theory. ReaxFF produced lithium diffusion maps of Li7PS6-LT and Li7PS6-HT clearly reproduces the formation of lithium diffusive cages around the sulfur atoms which validates the accuracy of the ReaxFF potential.

At the atomic scale, we characterized the energetics, composition, and transport properties of three low-energy (Σ3 and Σ5) symmetric tilt GBs in lithium argyrodites. Our findings indicate that the presence of GBs impede the diffusion of Li ions. The activation energies for Li-ion conduction crossing the grain boundaries are consistently higher than that of the bulk crystal which confirms the significant grain boundary resistance in this material. We also formulate a polycrystalline model to quantify the atomistic effects of the grain boundaries. In this talk, we have explored these results to critically understand the role of grain boundaries on Li conductivity, and how altering the microstructure can be utilized to optimize new high-performance SSEs for emerging ASSLMBs.
Effects of Aromatic Surfactants on Tin Electrodeposition
Authors: Fryer Algene , Huang Qiang
Published: December 2024

As the technology of quantum computing continues to develop, the necessity of finding materials that can be used to integrate the superconducting 3D architecture becomes more essential1. The electrodeposition of metals demonstrates an attainable way to manufacture vertical superconducting interconnects. In particular, Sn is one of the promising candidates to use because of its relatively high superconducting transition temperature (Tc) at 3.7 K, as well as its excellent manufacturability and self-passivation2. To ensure a void-free filling of the via like structure, organic additives that can function as suppressors, accelerators, or levelers will be needed to tune the deposition rate in the structure. While multi-additive systems have been used to control the deposition and the fabrication of conventional Cu interconnect structures, in other cases it has been demonstrated that a single additive can also enable the filling of Cu vias by suppressing the deposition at a certain range of potentials with a breakdown of the suppression occurring at another range3-4. Because of the importance of suppressive additives used in superconformal deposition, this work looks to explore the relationship between the degree of aromaticity and the level of suppression in additive assisted electrochemical deposition of Sn. Organic surfactant molecules including Igepal CO 520 and ethoxylated α-napthalenesulfonic acid (ENSA-6) are used for the comparative study in acidic stannous sulfate electrolytes.

The effects of the additives on the deposition are studied using cyclic voltammetry and chronoamperometric measurements. Both Igepal and ENSA-6 were able to suppress the deposition of tin while additives with similar molecular weight but no aromatic rings appear to have little impact. Furthermore, the suppression increases with concentrations of the additives, with varying degrees of aromaticity showing a slight difference in suppression strength. Finally, the adsorption and desorption of the additives as well as the deposition transients are studied by varying voltage sweep rate and electrode agitation, the results will be discussed in details.

References

Yanay, Y., Braumüller, J., Gustavsson, S., Oliver, W. D., & Tahan, C. (2020). Two-dimensional hard core Bose–Hubbard model with superconducting qubits. Npj Quantum Information, 6(1).

Huang, Q. (2023). Superconductivity of electrodeposited Sn films. Journal of The Electrochemical Society, 170(3), 032506.

Radisic, A., Lühn, O., Philipsen, H. G. G., El-Mekki, Z., Honore, M., Rodet, S., Armini, S., Drijbooms, C., Bender, H., & Ruythooren, W. (2011). Copper plating for 3D interconnects. Microelectronic Engineering, 88(5), 701–704.

Moffat, T. P., & Josell, D. (2012a). Extreme bottom-up superfilling of through-silicon-vias by damascene processing: Suppressor disruption, positive feedback and Turing patterns. Journal of The Electrochemical Society, 159(4).
Additives for the Formation of Cu Twin Structure by Electrodeposition
Authors: Lee Jeong Ho , Hwang Yoojin , Kim Myung Jun
Published: December 2024

Transistor scaling has faced limitations due to the inherent physical properties of semiconductors and challenges in fabrication processes. In light of this, the emergence of 3D packaging for semiconductors offers a promising avenue for achieving continual enhancement in the performance of electronic devices. The packaging technology facilitates the efficient arrangement of chips in both 2D and 3D configurations, enabling effective connections among multiple chips via metal interconnections. To achieve further performance improvements, there has been continuous emphasis on interconnection scaling in semiconductor packaging, driving extensive research into technologies capable of achieving smaller interconnection pitches. Hybrid bonding stands out as one of the next-generation technologies for stacking chips with much smaller pitches, relying on direct bonding between Cu pads and dielectrics. However, a significant challenge in direct Cu bonding is the high bonding temperature, which must be addressed through the development of better interconnection materials and bonding technologies. Recent studies have shown that the temperature for Cu-Cu direct bonding can be reduced by adopting highly (111)-oriented Cu or nano-twinned Cu. Nano-twinned Cu, in particular, ensures the formation of a (111)-oriented surface, leading to relatively rapid surface diffusion of Cu. Moreover, it has been reported that the strain energy released during the annealing of nano-twinned Cu can promote Cu-Cu direct bonding. Given the confirmed advantages of nano-twinned Cu in hybrid bonding, this study investigates the types of additives that induce nanotwin formation during Cu electrodeposition. We examine the effects of electrodeposition conditions, types, and concentrations of additives on Cu microstructures. By combining analytical results, we aim to suggest the optimal molecular structure and electrodeposition conditions to achieve twin structures effectively.
(Invited) Dynamically Vulcanized Polymer Electrolytes: New Materials for Solid-State Battery Systems
Authors: Caradant Lea , Foran Gabrielle , Lepage David , Nicolle Paul , Prébé Arnaud , Aymé-Perrot David , Dolle Mickael
Published: December 2024

A new type of polymer blend electrolyte was developed based on the principle of thermoplastic vulcanizates (TPV). TPV materials have been extensively used in the automotive and manufacturing sectors since the 1970’s. These vulcanized polymer have several desirable properties including strength, flexibility, amenability to reprocessing and customizability. However, these polymeric systems have yet to be introduced as electrolytes for use in battery systems. These electrolytes, which were obtained via melt-processing, combine the high ionic conductivity and processibility of a thermoplastic phase with the improved mechanical strength of a crosslinked elastomeric phase. TPV electrolytes prepared with poly(caprolactone) (PCL) (thermoplastic phase) and hydrogenated nitrile butadiene rubber (HNBR) (elastomeric phase) are presented in this work. These materials have properties that surpass those of non-crosslinked blends of PCL and HNBR. They deliver promising results in terms of ionic conductivity, electrochemical stability and mechanical strength. The presence of a cross-linked phase increases the elastic domain of the solid polymer electrolyte resulting in better resistance to volume changes of the active materials during cycling. Doping with a flame-retardant solvent, triethyl phosphate, allows ionic conductivity approaching that of PCL-LiTFSI to be obtained in the crosslinked electrolyte. However, unlike PCL-LiTFSI or even a non-crosslinked PCL-HNBR blend, the TPV still demonstrates creep resistance under a compressive force. Crosslinking also confers improved electrochemical stability which allows the material to be cycled with NMC-based electrodes.
Electrifying Sulfate Waste: A Sustainable Approach to Chemical Production and Gigaton-Scale Carbon Dioxide Removal
Authors: Jimenez-Villegas Santiago , Kim ChulOong , Delima Roxanna , Lammers Laura
Published: December 2024

Billions of tons of rock is processed every year by the mining industry to supply critical elements such as lithium, copper, and nickel for energy storage and phosphorus to the fertilizer industry. To date, the conventional extractive processes used by mining companies have been adequate in meeting global demands, albeit at the expense of the environment. The exorbitant quantities of waste (e.g., tailings and waste rock) produced by the extraction process have detrimental effects on ecosystems and surrounding communities, including the release of toxic metals and the onset of acid drainage.

Travertine Tech. has developed an innovative process for gigaton-scale carbon capture and sequestration that leverages sulfate waste from the mining and fertilizer industries. The process is driven by a salt-splitting electrolyzer that simultaneously generates sulfuric acid at the anode and sodium hydroxide at the cathode, using renewable energy. Sulfuric acid aids in extracting critical elements, while the generated base reacts with sulfate waste and atmospheric carbon dioxide to permanently sequester CO2 as carbonate minerals (via carbon mineralization). An increased demand for critical elements over the next several decades (particularly for energy storage and fertilizer applications) will supply sufficient waste to capture CO2 at the gigaton per year scale. Notably, for every ton of sulfuric acid produced, 0.45 tons of CO2 are permanently sequestered as carbonate minerals. This poster will present Travertine’s process—a transformative and economically viable solution to both climate change and resource sustainability.
Effect of Applied Voltage Value on Lithium 6 Isotope Enrichment By Intermittent Voltage Application Electrodialysis Method
Authors: Shin-mura Kiyoto , Fukusaka Takeru , Tokuyoshi Ryoya , Kitada Ayumi , Segami Yukari , Kato Kaito , Tazoe Hirofumi , Sasaki Kazuya
Published: December 2024

Thermonuclear fusion power generation assumes a nuclear fusion reaction between deuterium and tritium. Deuterium is abundant in seawater, and it is assumed that it can be recovered from there. Tritium rarely exists in nature. Therefore, tritium must be produced through a nuclear fission reaction between lithium and neutrons. Lithium exists stably in nature in the states of lithium 6 (6Li) and lithium 7 (7Li), and the isotope ratio is 6Li/7Li = 7.6/92.4. From the perspective of lithium production rate and energy balance, it is necessary to supply lithium with an isotope ratio of 6Li/7Li ≥ 90/10. The mercury amalgam method is the only practical method, but it has a large environmental impact [1]. Therefore, new 6Li isotope enrichment methods are being explored. One promising method is electrodialysis. Hoshino et al. reported that 6Li isotope enrichment could be achieved by electrodialysis using a porous polymer membrane impregnated with a liquid electrolyte [2, 3]. We have previously reported that 6Li isotope enrichment efficiency can be improved by applying a voltage with an appropriate intermittent profile to the front and back surfaces of the diaphragm of a lithium-ion conductive solid electrolyte membrane [3]. Here we investigated the effect of applied voltage during intermittent profile electrodialysis on isotope enrichment rate and lithium transfer rate. The isotope enrichment rate was determined by inductively coupled plasma mass spectrometry. In continuous voltage application, the 6Li isotope enrichment rate decreased as the applied voltage increased, but in intermittent voltage application, the 6Li isotope enrichment rate did not decrease as the applied voltage increased. Increasing the applied voltage increased the lithium transfer rate.

[1] S. C. Brooks, G. R. Southworth, Environmental Pollution, 159, (2011) 219−228.

[2] T. Hoshino, T. Terai, Fusion Eng. Des., 86(9-11), (2011) 2168-2171.

[3] T. Hoshino, T. Terai, J. Nuclear Materials, 417, (2011) 696-699.

[4] S. Honda, K. Shin-mura, K. Sasaki, J. Ceram. Soc. JPN, (2018) 331-335.
Electrochemical Ammonia Synthesis at Intermediate Temperatures Using Solid-State Phosphate Electrolyte
Authors: Nakashima Yamato , Tada Shohei , Kikuchi Ryuuji
Published: December 2024

As we aim to realize a carbon-neutral sustainable society and a CO2-free society, methods of converting renewable energy into hydrogen and then further into a hydrogen carrier with high energy density are attracting much attention. Among various energy carrier materials, ammonia is regarded as a promising candidate, which has a high hydrogen content and is easy to transport and store. Currently, ammonia is industrially produced by the Haber-Bosch process under high-temperature and high-pressure conditions, which is energy intensive and has a large environmental impact. Therefore, in this study, we focused on electrolytic synthesis under mild conditions.

Due to the operating temperature constraints of the electrolyte, ammonia electrosynthesis is mainly classified into three temperature ranges: low temperature range below 100℃, high temperature range above 500℃, and medium temperature range from 100℃ to 500℃. Since ammonia synthesis from hydrogen and nitrogen is exothermic, synthesis at a low temperature is thermodynamically advantageous, but the disadvantage is that the reaction rate is limited because N2 molecules are difficult to active at low temperatures. On the other hand, although NH3 synthesis proceeds at a high reaction rate in the high temperature range, decomposition of ammonia in the reverse reaction is also likely to occur, leading to low equilibrium conversion of N2. Based on these considerations, we target NH3 synthesis in the intermediate temperature range, which is expected to have both the advantages of the low-temperature and high-temperature types, namely thermodynamic and kinetic advantages. In addition, ammonia synthesis was performed using a solid-state phosphate electrolyte that exhibits high proton conductivity and stability in the intermediate temperature range, and research focus was posed on cathode catalysts to raise the ammonia production rate and faradaic efficiency simultaneously. In this study, we have investigated Fe, which has a high dissociation activity for nitrogen molecules, and the first candidate for the cathode catalyst was a composite catalyst of Fe and yttrium-doped barium zirconate (BZY), that had shown the yield rate and faradaic efficiency at 220℃ and ambient pressure. [1]

First, ammonia electrosynthesis was performed using Fe/BZY-Ru as cathode catalyst, in which RuO2 was added to Fe/BZY to maintain the reduced state of Fe. The highest NH3 yield rate of 2.7x10-10 mol (s cm2)-1 was achieved at -1.5 V (vs. open-circuit voltage (OCV)) and the highest faradaic efficiency of 0.3% was achieved at -0.5 V (vs. OCV). This low faradaic efficiency was thought to be derived from H2 generation as a side reaction of NH3 generation, so we started electrosynthesis using Fe/BZY without RuO2 as a cathode catalyst. As a result, the faradaic efficiency of 4.8％ was achieved at -1.5 V (vs. OCV) with the NH3 yield rate of 2.1x10-10 mol (s cm2)-1.

[1] Y. Yuan, S. Tada, R. Kikuchi, Mater. Adv., 2, 793 (2021).
(Keynote) Atomic Layer Processing in Semiconductor Research and Development
Authors: Metz Matthew V.
Published: December 2024

As semiconductor process technology has evolved from node to more advanced node, continued atomic layer processing innovations in materials and hardware have improved film quality, device performance and overall cost. In this talk, Intel will cover atomic layer processes and where they have been critical to the high-volume manufacturing of transformational new semiconductor products.

As the semiconductor industry moves into the gate all around RibbonFET era, atomic layer control is required across more layers with ever increasing geometric complexity. New device architectures institute hard limits on film thickness which make atomic layer processes ideal. In fact, for some applications, the low growth per cycle or etch per cycle of atomic layer processes are required to achieve the fine control needed for optimal device performance. Other traditionally used deposition techniques will not be able to scale to these new devices; atomic layer processes will need to step in by delivering high quality dielectrics, metals and semiconductor materials into smaller, more complex device shapes. These materials are often multi-component and require precise compositional control, including that of dopants. Next generation devices are increasing multi-colored meaning that an increasing variety of materials are found in close proximity to each other. The ability to selectively place materials only where needed, through intrinsically selective processes, inhibitor chemistries and/or subsequent selective etch techniques can enable new structures and reduce patterning costs. Molecular layer deposition of EUV photoresists is also being explored to introduce high absorptivity elements for next generation lithographic patterning. These challenges, and the resultant opportunities, will be magnified as coplanar CMOS nanoribbon devices are replaced with stacked nanoribbon architectures.

Finally, we will cover the largest opportunities for future devices, covering needs for atomic layer processes for the integration of two-dimensional materials, e.g., graphene or transition metal dichalcogenides, and the emerging field of epitaxial complex oxides for ultra-low energy devices which necessitate the development of chemical vapor phase etches of non-traditional materials for the semiconductor industry.
(Digital Presentation) Investigation of Nanoconfined Wet Etching Mechanism Using MD Simulation
Authors: Yoshida Yuki , Nakano Takeo , Kumari Sangita , Hu Shan , D’elia Peter
Published: December 2024

With the advancement in semiconductor technology, sophisticated multidimensional geometries are being formed resulting in nonconfined spaces. Wet etching these nanoconfined spaces uniformly across different CD sizes is challenging. Typically, etch (ER) decreases with decrease in CD size. One of the reported mechanisms to explain this behavior is the overlapping of electrical double layer (EDL) which prevents the etchants from entering to the nanochannels. In our previous experimental work, we reported a reverse ER trend (ER increase with decrease in CD size) of SiO2 using HF in organic as medium compared to water as medium. These results suggested that EDL model alone cannot explain the full mechanism and other factors need to be considered. Hence, molecular dynamics (MD) simulations are used to explain the mechanism of nanoconfined etching of SiO2 in water and organic solvent.

Fig.1 shows the MD simulation result of the number density distribution of diluted HF at the solid-liquid interface in a nanoconfined spaces. When water is the solvent, HF molecules are strongly adsorbed in the solid interface. However, with the organic solvent, the HF molecules are more uniformly distributed in the volume near the surface. As the CD becomes smaller, the HF molecular density in the intermediate region in the space tends to decrease in the aqueous solution and increase in the organic solution. Next, we calculated the diffusion time of HF molecules in the nano-confined trench using the MD simulations, where we found that HF molecules have a faster diffusion time in water than in the organic solvent. This is due to the difference in the interaction between the solid interface, the HF molecules, and the solvent in addition to the viscosity of the solvent.

Using EDL model and etching reaction, here we report the wet etching mechanism of nanoconfined spaces from the MD simulation result.

Figure 1
(Invited) Epitaxy Strategies for Monolithic 3D Integration of Single-Crystalline Semiconductors
Authors: Kim Jeehwan
Published: December 2024

Continuing miniaturization of devices has reached its limits as a means to boost the performance of cutting-edge electronic products. Instead, 3D heterogeneous integration, which involves vertically stacking wafers with embedded electronic devices, is emerging as the leading approach for augmenting performance. This method, however, demands complex procedures including: creating through-silicon vias (TSVs), filling these vias with copper, and bonding the wafers via micro-bumps or Cu hybrid bonding. Eliminating the use of wafers in this complex 3D assembly could streamline the process and reduce the length of data paths. Yet, current technologies scarcely allow for the removal and reassembly of active single-crystalline devices from wafers. Moreover, directly depositing device layers onto existing circuits presents additional hurdles. Over the last decade, we have pioneered techniques for transferring single-crystalline semiconductor device membranes, significantly advancing 3D heterogeneous integration [1-8]. More recently, we have achieved a breakthrough in monolithically growing pristine single-crystalline 2D semiconductors on non-crystalline insulators at a BEOL compatible temperature, pushing the boundaries of monolithic 3D heterointegration even further [9]. In my presentation, I will explore our unprecedented 3D integration methods and their implications for state-of-the-art electronics [9, 10], optoelectronics [11], and bioelectronics [12-13].

References: [1] Nature 544, 340 (2017), [2] Nature Materials 17, 999 (2018), [3] Nature Materials 18, 550 (2019), [4] Nature Nanotechnology 15, 272-276 (2020), [5] Nature Electronics, 2, 439 (2019), [6] Nature, 578, 75 (2020), [7] Nature Nanotechnology 15, 574 (2020), [8] Nature Nanotechnology, 17, 1054 (2022), [9] Nature, 614, 88 (2023), [10] Nature Electronics, 5, 386 (2022), [11] Nature, 614, 81 (2023), [12] Science Advances, 7, 27 (2021) [13] Science 377, 859 (2022)
(Invited) 3D Integration of 2D Devices for Advanced Memory, Logic, and Bio-Inspired Computing
Authors: Das Saptarshi
Published: December 2024

In this presentation, I will delve into the exciting realm of monolithic 3D integration, where emerging 2D FETs take center stage, empowering advanced memory, and logic devices. Furthermore, I will also discuss our work on bio-inspired neuromorphic computing. Notably, our recent breakthroughs have culminated in the successful demonstration of wafer-scale 2-tier and 3-tier 3D integration, utilizing MoS2 and WSe2 FETs as the building blocks. These achievements have paved the way for multifunctional circuits that hold immense promise for the future of electronics. Delving deeper into our research, we have harnessed the potential of 2D materials to design solid-state devices with low power consumption mimicking auditory processing in barn owl, collision avoidance in locust, and probabilistic computing in dragonfly. By combining the power of 2D materials with bio-inspired principles, our work lays a solid foundation for the creation of highly compact and functionally diverse integrated circuits in the revolutionary third dimension. The implications of this technology are far-reaching and hold the potential to shape the future of electronics and computing.
Multiscale Electrochemical Interface and Interphase Simulation: Insights from Operando Conditions and Machine Learning
Authors: Cheng Tao
Published: December 2024

Elucidating the atomic structures of electrochemical interfaces and interphases is pivotal in advancing our understanding of various electrochemical processes. Our research introduces advanced multiscale simulation methods and a hybrid algorithm for accurately simulating the electrolyte/electrode interface and electrochemical reactions under operando conditions.[1] These approaches have enabled us to elucidate the reaction mechanism of CO2 reduction on copper surfaces and to detail the atomic structure of the solid electrolyte interphase (SEI) in Lithium/Sodium metal batteries at the nanoscale.[2,3] Incorporating machine learning (ML) with physic models, we have significantly enhanced the efficiency and accuracy of surface spectroscopy calculations,[4] offering new insights that accelerate material design and the development of next-generation electrochemical systems.
Solution-Processable Metal-Oxide Thin-Film Transistors with Radiation Resistance
Authors: Ho Dongil , Kim Choongik , Kim Myung-Gil
Published: December 2024

The impact of 5 MeV high-energy proton irradiation on solution-processed metal-oxide thin-film transistors (TFTs) has been studied. TFTs based on zinc oxide (ZnO) and indium gallium zinc oxide (a-IGZO) showed a substantial negative shift in threshold voltage values (ΔVth ≤ −30 V) or transitioned to a conductor state as the proton radiation dose increased. This effect is attributed to the formation of proton irradiation-induced oxygen vacancies in the metal-oxide semiconductor layer. Conversely, zinc tin oxide (ZTO) devices with an optimized composition demonstrated good stability due to the strong oxygen binding characteristics of tin atoms. Additionally, back-channel passivation of oxide semiconductor TFTs with an n-type organic semiconductor layer significantly improved device stability. Our research indicates that solution-processed metal oxide semiconductors hold significant promise as radiation-resistant large-area electronic devices for nuclear and aerospace applications.
Formation of Source/Drain Structures Using Nanosecond Laser Annealing for Multichannel GAA Mosfet Devices
Authors: Jung Hosun , Ko Dae-Hong
Published: December 2024

As metal-oxide-semiconductor field-effect transistors (MOSFETs) devices approach their dimensional scaling limits, 3D structures such as gate-all-around FETs (GAAFETs) have been introduced to improve the electrical characteristics of transistors by increasing the effective channel width. In modern logic devices with a GAA structure, in-situ doped epitaxial silicon is grown on recessed source/drain (S/D) regions using selective epitaxial growth (SEG) process. However, the SEG process poses a competitive disadvantage in terms of complexity and cost. To simplify the integration process, we propose a method for forming S/D without relying on SEG. In this study, we investigate the formation of S/D using nanosecond laser annealing process in devices with multilayer channels. Three pairs of Si/Si0.7Ge0.3 multilayer films were deposited on Si (100) substrates using ultra-high vacuum chemical vapor deposition (UHVCVD). After deposition, boron and phosphorus dopants were implanted into the structure. Samples were then subjected to nanosecond laser annealing under various conditions using a krypton fluoride (KrF) pulse laser. Finally, we obtained recrystallized and doped films that function as S/D. Transmission electron microscopy (TEM) confirmed the microstructure of recrystallized films as function of increasing laser power density. Additionally, the dopant distribution was analyzed using secondary ion mass spectrometry (SIMS). High resolution X-ray diffraction (HR-XRD) was employed to examine the strain behavior in the films. Results indicate that the nanosecond laser annealing process is a viable method for forming S/D in devices with Si/SiGe multilayer channels.

Acknowledgements

This work was supported by the Joint Program for Samsung Electronics at Yonsei University and the Technology Innovation Program (20010598) funded by the Ministry of Trade, Industry & Energy (MOTIE).
Investigation on Characteristics of in Situ Boron-Doped Sige Epitaxy below 600℃
Authors: Yoon Dongmin , Jung Seonwoong , Shin Hyerin , Oh Seokmin , Kim Jungwoo , Ko Dae-Hong
Published: December 2024

Boron-doped SiGe is widely used as a source/drain (S/D) material in p-type metal-oxide–semiconductor field-effect transistors (FETs). With the advent of strain engineering in 90-nm node technology, selective epitaxial growth (SEG) with in situ doping has become a standard process for S/D material formation and continues to be employed in advanced architectures such as FinFETs and gate-all-around FETs. Traditionally, SiGe SEG processes have been conducted at temperatures above 600℃ [1]. However, the growing demand for low-temperature processes has led to increased interest in boron-doped SiGe epitaxy below 600℃. For example, to reduce S/D contact resistivity, highly doped SiGe epitaxy has been proposed in post-gate processes where low temperatures are crucial to prevent deformation of high-k oxide/metal gates [2]. Additionally, in monolithic complementary FETs—considered for sub 1-nm node logic device—low-temperature processing is required to minimize the thermal influence on the bottom FET during S/D formation for the top FET [3].

This study investigates in situ boron-doped SiGe epitaxial layers grown in an ultra-high vacuum chemical vapor deposition system at temperatures below 600℃. The focus of this study is to understand the growth characteristics of films by analyzing how different growth conditions affect film properties. Secondary ion mass spectrometry was employed to measure the chemical concentrations of boron and germanium in the films. High-resolution X-ray diffractometry was used to calculate the lattice parameters of the boron-doped SiGe films, allowing determination of substitutional boron concentrations, which were then compared to chemical boron concentrations. In addition, atomic force microscopy was used to analyze the surface morphology of the films. These analyses provide a comprehensive investigation of the overall film properties and growth characteristics of boron-doped SiGe films grown at temperatures below 600℃.

Acknowledgments

This work was supported by the Technology Innovation Programs (RS-2023-00235609) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).

References

[1] Hartmann, J. M., et al. "Selective epitaxial growth of boron-and phosphorus-doped Si and SiGe for raised sources and drains." Journal of crystal growth1-3 (2004): 36-47.

[2] Breil, N., et al. "Contact cavity shaping and selective SiGe: B low-temperature epitaxy process solution for sub 10-9 Ω. cm 2 contact resistivity in nonplanar FETs." 2023 IEEE Symposium on VLSI Technology and Circuits (VLSI Technology and Circuits). IEEE, 2023.

[3] Subramanian, S., et al. "First monolithic integration of 3d complementary fet (cfet) on 300mm wafers." 2020 Ieee Symposium on Vlsi Technology. IEEE, 2020.
Revisiting Band Tails and Localized States in Amorphous Semiconductors
Authors: Luo Yuezhou , Flewitt Andrew J. John
Published: December 2024

Amorphous semiconductors, such as hydrogenated amorphous silicon (a-Si:H) and amorphous indium gallium zinc oxide (a-IGZO) have been central to the development of thin film transistors (TFTs) for large-area electronic applications such as displays. This is a result of the exceptional material uniformity that can be achieved when depositing over very large areas (~10 m2). This means that all TFTs are essentially identical over an entire large display panel. However, there is a technological price to pay – the carrier mobility is generally less in amorphous semiconductors compared to their crystalline equivalent.

The origin of this reduced carrier mobility is a result of a key difference in the density of states between crystalline semiconductors and their amorphous counterparts. The long-range order of a crystalline lattice means that all carrier states in the conduction and valence bands exist over long distances. These ‘extended states’ are associated with generally high mobility carriers. However, there is no long-range order in amorphous semiconductors, but only short-range order over one to two bond lengths associated with local atomic coordination requirements (and to some degree a medium-range order over a few bond lengths). The result is that the bottom of the conduction band and top of the valence band gain ‘tail’ states which are localized in nature.

Not only do these localized states frequently dominate (or at least significantly affect) conduction in amorphous semiconductors and hence the switching characteristics of TFTs, but they also have a role to play in other important processes such as hysteresis and bias stress instability. But what are these localized band tail states, how should we think about them in the context of conduction and how do they relate to extended states?

These questions are revisited from the starting point that there is a perturbation in the delocalized charge concentration with position in an amorphous semiconductor compared to its crystalline counterpart, and this can be quantified as a spatially varying excess charge concentration (where a deficit is just a negative excess). The rate of spatial variation is long relative to the rate of change in the electron wavefunction, and reflects the short- and medium-range order distances. Charge conservation means that that this excess charge concentration will have a mean of zero and a Gaussian probability distribution is assumed. A model using this as a starting point has been created which reproduces band tails and which provides new insights into their physics which are discussed.