bluuebunny/crossref_metadata_2025 huggingface dataset:
Nature of Instability in Electrokinetics-Based Anodic Oxide Pore Formation
Authors: Wankhede Sajal , Pillai Dipin S.
Published: December 2024

The anodization process of aluminium in acidic electrolytes facilitates the formation of nano-porous aluminium oxide. A simplified model for anodization is formulated, incorporating essential physics such as high field conduction, Butler-Volmer electrokinetics for oxide formation and dissolution at the oxide-electrolyte interface, effect of Laplace pressure on the activation energy of oxide-electrolyte interfacial reactions. A linear stability analysis suggests that the oxide film is rendered unstable to perturbations of well-defined wavelength for specific range of parameters such as anodizing efficiency, applied voltage and electrolyte pH. The analysis is then extended to the weakly nonlinear regime to determine the nature of instability, i.e., whether it is subcritical or supercritical instability beyond the stability threshold. Our findings indicate that the solutions arising from neutral stability exhibit a subcritical nature (cf. Figure 1), in agreement with experimental observations of pore formation.

Figure 1
Environmental, Processing, and Fabrication Factors Affecting Pitting Corrosion of SS316L
Authors: Fatima Tasnia , Carvalho Ricardo , Gupta Rajeev Kumar , Rincon Troconis Brendy Carolina
Published: December 2024

The maintenance and repair of the storage canister for spent nuclear fuel are of importance to safely maintaining the national strategic fuel supply chain. End-of-life storage is an integral component of the infrastructure supporting the long-term viability of the existing U.S. reactor fleet. Stainless steels (SSs) are widely used as a structural material for nuclear power plants. Specifically, in the dry storage of spent nuclear fuels within the concrete cask, SS canisters are used as an important barrier to separate spent fuel (radioactive material) and the environment. Due to the formation of a protective passive film, austenitic SSs have a wide spectrum of resistance to atmospheric corrosion. However, such passive film is susceptible to breakdown in the presence of chloride ions, resulting in pitting corrosion. It is known that RH and temperature fluctuations tend to influence corrosion under natural exposure conditions. Nevertheless, most work performed up to date primarily includes immersion testing. In addition, the fabrication method of the canisters includes welding and if it is not heat treated correctly, it can introduce a sensitized microstructure.

In this research the initial stage of atmospheric corrosion under seawater and MgCl2 solutions droplets on austenitic SS 316L was evaluated. The current research aims to understand the effect of environmental, fabrication (specifically additive anufacturing), and processing parameters such as droplet size, relative humidity (RH), sensitization, temperature, and chloride droplet solution on the atmospheric pitting corrosion of SS 316L. For this purpose, atmospheric pitting resistance testing, electrochemical techniques (under atmospheric and immersion conditions), microstructure characterization, and thermodynamic modeling were performed using potentiodynamic polarization, double loop electrochemical potentiokinetic reactivation, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), ThermoCalc and JmatPro.

The results indicate that increasing temperature, droplet size and decreasing in RH tends to decrease pitting resistance (individual effects). Moreover, exposure to MgCl2 droplets led to higher pitting corrosion susceptibility than seawater droplets. The environmental effect was also observed on pit morphology (faceted, shallow, equiaxial, columnar pitting). Alloy fabrication methods have a large effect on pitting. The pitting resistance of a emergent material, in this case carbon nanotube reinforced SS 316L and 3D printed using selective laser melting (SLM) technique, showed enhanced pitting resistance (2 % carbon nanotube composition). Sensitization has a deleterious effect on pitting corrosion.

The results from this work will provide knowledge, not currently existent in the literature for SS 316L (conventional and SLM) to inform the safe conditions to operate nuclear waste storages and predict their life-cycle.
(Invited) Metal-Assisted Chemical Etch of Semiconductors: Fundamentals and Applications
Authors: Li Xiuling
Published: December 2024

Metal-Assisted Chemical Etch (MacEtch), an unorthodox semiconductor etching method, enables damage-free fabrication of semiconductor nanostructures with unprecedentedly high aspect ratios. By harnessing the intricate interplay of local catalysis and electron transfer effects at the metal-semiconductor-solution interface, MacEtch transcends the definition of conventional chemical etching. In this talk, I will introduce the MacEtch characteristics and present a systematic study of the ensemble electrochemical mechanisms that govern the photo-enhanced MacEtch process of wide and ultrawide bandgap semiconductors including GaN, SiC, and Ga2O3, as well as related heterojunctions. The effects of local cathode and anode design, energy-band alignments, and solution chemistry on MacEtch are correlated with the underlying electronic mechanisms of carrier generation, annihilation, transport, and extraction. I will also provide a few examples of device applications of MacEtch. First, nearly size-independent external quantum efficiency (EQE) for III-N µLED fabricated using the MacEtch approach is achieved, overcoming one of the biggest hurdles in µLED technology -- the efficiency degradation with shrinking pixel size, due to plasma-etching damage. Secondly, fabricated by MacEtch, smooth and high aspect ratio sidewall finFETs of β-Ga2O3, an emerging ultrawide bandgap semiconductor with a bandgap of ~ 4.8 eV, are demonstrated to have a record-low specific on-resistance and DC transfer characteristics with near zero hysteresis. We believe that the simplicity, versatility, and scalability of MacEtch will continue to catalyze a myriad of applications in electronics, photonics, energy, quantum technologies, and bio-sensing.
(Invited) Titania Nanotube Layers as Anodes for Li-Ion Microbatteries
Authors: Djenizian Thierry
Published: December 2024

With many advantages such as high surface area and improved charge transport, self-supported 3-D nanostructured metal oxides such as titania nanotubes (TNT) layers are promising electrode materials for Li-ion microbatteries.

This presentation will review the fabrication of Li-ion microbatteries using as-formed and chemically modified TNTs as negative electrodes [1-9]. Effects of material selection and processing on the performance and reliability are presented as a means to develop conceptual guidelines to understand and improve microbattery designs. Different chemical modifications of nanotubes by ALD technique [10-13] and by the conformal electrodeposition of polymer electrolytes [14] for enhanced electrochemical performance will be presented. Fabrication of full 3D microcells showing high electrochemical performance will be shown and the development of the next generation of 3D flexible microbatteries will be also introduced.

REFERENCES

[1] V. Galstyan, J. Macak, T. Djenizian, App. Mater. Today,
29, 101613 (2022).

[2] N. Plylahan, M. Letiche, M. Barr, and T. Djenizian, Electrochem. Commun., 43, 121 (2014).

[3] N. Plylahan, A. Demoulin, C. Lebouin, P. Knauth, T. Djenizian, RSC Adv., 5, 28474 (2015).

[4] N. Plylahan, M. Letiche, M. Barr, B. Ellis, S. Maria, T. N. T. Phan, E. Bloch, P. Knauth, and T. Djenizian, J. Power Sources, 273,

1182 (2015).

[5] G. Salian, C. Lebouin, A. Demoulin, S. Maria, P. Knauth, M. Lepihin, A. Galeyeva, A. Kurbatov, and T. Djenizian,

Power Sources, 340, 242 (2017).

[6] I. V. Ferrari, M. Braglia, T. Djenizian, and P. Knauth, J. Power Sources, 353, 95 (2017).

[7] G. Salian, B. M. Koo, C. Lefevre, T. Cottineau, C. Lebouin, A. T. Tesfaye, P. Knauth, V. Keller, T. Djenizian, Adv. Mater. Technol.,

3, 1700274 (2018).

[8] Fraoucene, V. A. Sugiawati, D. Hatem, M. S. Belkaid, F. Vacandio, M. Eyraud, M. Pasquinelli, T. Djenizian, Front. Chem.,

7, 66 (2019).

[9] G. D. Salian, C. Lebouin, M. Galeyeva, A. P. Kurbatov, T. Djenizian, Front. Chem., 7, 675 (2019).

[10] H. Sopha, et al, Materials Chemistry and Physics, 276, 125307 (2022).

[11] H. Sopha, et al, Flat. Chem., 17, 100130 (2019).

[12] A. T. Tesfaye, et al, Nanomaterials, 10, 953 (2020).

[13] H. Sopha, et al, ACS Omega, 2, 2749 (2017).

[14] V. A. Sugiawati, F. Vacandio, T. Djenizian, Molecules,
25, 2121 (2020).
(Invited) Finite Element Modeling of Atmospheric Corrosion: Boundary Conditions, Model Fidelities, and Computational Advances with Machine Learning
Authors: Katona Ryan Michael , Venkatraman Aditya , Roop Matthew , Noell Philip James , Montes de Oca Zapiain David , Schaller Rebecca Filardo
Published: December 2024

Corrosion is a detrimental materials degradation mechanism to many in-service systems, especially in marine environments. Due to the large array of influential variables, atmospheric corrosion can be expensive (time, materials, replications, etc.) to evaluate experimentally. To reduce these costs, Finite Element Method (FEM) simulations can be used to assess the rate and extent of corrosion. While a useful tool, complexities in FEM can substantially influence computational time and accuracy of model outputs. These complexities include experimental variation in boundary conditions to various levels of physics fidelities. Herein, the importance of boundary conditions is explored: identifying critical parameters for accurate simulations in atmospheric scenarios and weighing the computational cost and accuracy of high and low fidelity models.

Further, accelerations of FEM predictions have recently been achieved to decrease computational time to make predictions, identify additional experiments where error reduction is possible, and make high fidelity predictions for a wide parameter space at a fraction of the cost. The efficacy of this protocol will be showcased for galvanic corrosion minimizing the number of simulations necessary to obtain accurate predictions of the current and damage outputs. The protocols developed and demonstrated in this work provide a powerful tool for screening various forms of corrosion under in-service conditions.

Acknowledgements

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. This document is SAND 2024-03970C.
Accelerating Computational Calculations of Galvanic Corrosion Using Active Learning
Authors: Montes de Oca Zapiain David , Venkatraman Aditya , Maestas Demitri , Melia Michael Anthony , Noell Philip James , Katona Ryan
Published: December 2024

Corrosion affects metallic surfaces when exposed to different atmospheric conditions. The magnitude of corrosion (and its damage) is affected by various different factors such as environmental, chemical, as well as the geometry of the part. Accurate computational predictions and estimates of corrosion can be obtained by numerically solving the complex differential equations that describe corrosion using the finite element method (FEM). However, despite its accuracy, FEM-based protocols are ill-equiped for an efficient exploration of the design space to identify factors that foment (or deter corrosion) given that they are iterative in nature and require significant computational power. Moreover, FEM protocols require experimental results to calibrate and define the boundary conditions of the simualtions, which unfortunately adds to the overall expense and time. Therefore, an accelerated protocol for obtaining accurate predictions of corrosion quantities of interest is desperately needed. In this work we introduce a robust model building protocol for calibrating and establishing accurate machine learning based corrosion surrogate models using state-of-the-art machine learning models and active learning. The active learning aspect of the work enables for an automated and data-driven framework for identifying and incorporating experimental measurements and their corresponding FEM results that will yield the maximum information gain and enhance performance of the developed surrogate model. Therefore, providing a powerful tool for screening corrosion performance.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. SAND No. SAND2024-03628A
(Invited) Atmospheric Corrosion Studies for Corrosivity Categorization in Alaska
Authors: Srinivasan Raghu , Hunter Jozef
Published: December 2024

In colder climates, factors like substantial snowfall, frequent freeze-thaw cycles, the use of de-icing salts, and increasing global temperatures add complexities to the established paradigms governing atmospheric corrosion. To elucidate the mechanisms of atmospheric corrosion under colder temperatures, four distinct test sites were established in the state of Alaska, USA. Each site was equipped with a modern, multi-angle exposure test rack coupled with an auxiliary weather station. Within these setups, five commonly used metal alloys were exposed at 0-, 30-, and 45 degrees from the horizontal over 6- and 12-month periods. Weather correlation analysis, mass loss analysis, SEM/EDXA, and optical profilometry studies were conducted following the exposure of the metal specimens to determine corrosion rates (CR) and damage. The measured CR, exposure angle, and accompanying meteorological data—specifically, temperature, relative humidity, time of wetness, precipitation, chlorides, and sulfates—were benchmarked against ISO standards to classify and categorize the corrosivity of the four test sites in Alaska. The PSCA test site (Kodiak, AK) was the most aggressive environment regarding all weather parameters. UAF (Fairbanks, AK) was the least aggressive, and test sites PAA (Port of Anchorage, AK) and UAA (University of Anchorage, AK) showed mild to moderate aggressiveness. Samples exposed at 0° consistently showed higher corrosion rates than those exposed at 30° and 45° across all instances. At the more aggressive PSCA site, a distinct correlation was observed between the exposure angle and CR with samples exposed at 0° showing the highest CR, followed by 30°, then 45°. Optical profilometry studies revealed that the comparison of surface roughness between the exposed samples followed an extremely similar pattern to that of CR. Corrosivity categorization based on CR from experimental mass loss data varied from the estimation of CR through existing dose-response functions and weather parameters. Newer standardized models involving more weather parameters are required to better estimate and predict corrosivity in colder climates. Alaska's growing role as a critical military, cargo, shipping, and refueling hub enhances its importance as an ideal natural laboratory for studying atmospheric corrosion in cold regions, as demonstrated by the developed test sites discussed in this paper.
Electrolyte pH-Driven Formation of Zinc Hydroxide Bromide Precipitates: Characterization and Mitigation in Static Zinc-Bromine Batteries
Authors: Ju Dongrun , Steingart Daniel A. , Mohr Robert , Irvin Lynne Elizabeth , Sirkoch Curtis Hammond
Published: December 2024

The transition towards renewable energy sources necessitates the development of efficient and cost-effective energy storage solutions to mitigate the intermittent nature of these resources. Static zinc-bromine batteries (ZBBs) have emerged as a promising, safe, and low-cost grid electrochemical energy storage device. However, their long-term cycling performance suffers from undesirable side reactions, specifically, a precipitation reaction at the cathode during cycling. This precipitate, identified as layered polycrystalline zinc hydroxide bromide (ZHB) for the first time, increases charge transfer resistance and reduces efficiency and capacity. While its formation mechanism remains unclear, our study investigates the effects of electrolyte composition, pH variation, and charging conditions on the precipitation using electroanalytical techniques. We propose that electrolyte pH changes caused by concentration polarization at the cathode surface during charging and hydrogen ion loss are major drivers of ZHB formation. Controlling these parameters can potentially suppress this detrimental precipitate, improving the long-term performance of ZBB.
(Keynote) Controlling Ion Migration in Metal Halide Perovskites for Better Solar Cell Stability
Authors: Kamat Prashant V , Szabo Gabor
Published: December 2024

The ability to tune the bandgap of metal halide perovskites through compositional alloying of the halide ion is of interest in designing tandem solar cells and light emitting displays. However, photoinduced migration of halide ions can significantly affect the device performance. One such property is photoinduced phase segregation in mixed halide perovskites (MHP), which forms bromide rich and iodide-rich domains. These domains act as charge carrier traps and lower the efficiency of perovskite-based devices.[1,2] The thermodynamic and redox properties of halide perovskites provide a strong driving force for hole trapping and oxidation of iodide species. Thus, the mobility of halides and their susceptibility to hole-induced oxidation play a crucial role in determining the long-term stability of metal halide perovskite solar cells.

When Ruddlesden-Popper 2D mixed-halide perovskite films with spacer cations such as butylammonium are introduced into three-dimensional (3D) perovskite films, they can stabilize them against moisture-induced degradation at room temperature. While such passivation of 3D perovskites using 2D perovskites has been reported widely, the instability of the 2D/3D interface during long term solar cell operation can be problematic.[3,4] The cation migration under light and heat can significantly alter the 2D/3D interface, thus affecting the solar cell performance. Thus, suppression of halide ion migration as well as cation migration remains a key factor in achieving long term stability and improving efficiency of perovskite solar cells and light emitting devices.
Manufacturing [001]-Oriented FAPbI3 Photodetectors Exhibiting Outstanding Air Stability through Eco-Friendly Anti-Solvent Additive Engineering
Authors: Yun Kwang-Ro , Seong Tae-Yeon
Published: December 2024

Organic-inorganic halide perovskite (OIHP) have gained widespread attention for various optoelectronic applications, including photovoltaics, thin-film transistors, and light-emitting diodes. Among them, OIHPs stand out as promising materials for photodetector applications due to their exceptional optoelectronic properties such as long exciton diffusion length, low exciton binding energy, high absorption coefficient, and tunable bandgap. Anti-solvent engineering is crucial method for enhancing performance of OIHP films by facilitating nucleation and crystal growth. However, traditional anti-solvent engineering often requires toxic solvents, hindering commercialization and scalability. Research focusing on non-toxic green antisolvents is gaining traction, but commonly used green anti-solvent such as isopropanol (IPA) and ethyl acetate leave residues that can impede crystal growth during thermal annealing, posing a challenge to achieving high-quality OIHP films.

Among OIHP materials, methylammonium lead triiodide (MAPbI3) is widely used in photodetector applications but suffers from thermal instability. Formamidinium lead triiodide (FAPbI3) shows superior thermal stability but undergoes a phase transition from black α-FAPbI3 to yellow δ-FAPbI3, adversely affecting device performance. Stabilizing highly crystalline phase pure α-FAPbI3 films is crucial for achieving high-performance FAPbI3-based photodetectors. The crystal facets of FAPbI3 significantly impact stability and performance, with the (001) facet being more stable and suitable for high-performance photodetectors. Various methods, including additive engineering, have been explored to grow perovskite films with [001] preferential orientation.

In this study, we demonstrated the growth of highly crystalline and phase pure α-FAPbI3 films using anti-solvent additive engineering (AAE) with green anti-solvent IPA and organic spacer phenethylammonium iodide (PEAI). The PEAI-AAE treatment induced [001]-preferred orientation growth, enhancing crystallinity and reducing defect density. Photodetectors fabricated using PEAI-AAE treated FAPbI3 exhibited high responsivity of 24.89 A‧W-1, excellent specific detectivity of 1.56×1013
Jones, and rapid response times of 450 μs (rise time) and 530 μs (fall time). Additionally, PEAI-AAE treatment improved surface hydrophobicity, enhancing device stability. Our findings offer insight into advancing FAPbI3-base photodetectors for practical optoelectronic applications.
(Invited) Development of Lead and Lead-Free Solution-Processed Solar Cells Using Automated Experiments
Authors: Saeki Akinori
Published: December 2024

A wave of digital transformation not only propels social service and commercial production, but also reenergizes a method of material science research that has traditionally relied on personal experience/idea, serendipitous findings, and trial-and-error experiments. Machine learning (ML), which makes use of ever-expanding artificial intelligence (AI) technology, provides an alternative path to a target material and broadens the region of chemical spaces explored. To develop an ML model that necessitates a large volume of data, theoretical calculations and manual translations from published works are commonly used. However, these data augmentations involve critical issues such as experimental compatibility, data bias, and inconsistency among the collected data. Automation of experiments that enables high-throughput and high-accuracy measurements is a viable solution to these problems. Owing to the recent advancement in robotics and AI, a high-performing and relatively affordable robot is available for automated experiments.

Solution-processed inorganic solar cells with less toxic and earth-abundant elements are emerging as viable alternatives to high-performance lead-halide perovskite solar cells.2,3 However, the wide range of elements and process parameters impedes the rapid exploration of vast chemical spaces. Here, we developed an automated robot-embedded measurement system that performs photoabsorption spectroscopy, optical microscopy, and white-light-flash time-resolved microwave conductivity (TRMC). We tested 576 films of quaternary element-blended wide-bandgap Cs–Bi–Sb–I semiconductors with various compositions, organic salt additives (MACl, FACl, MAI, and FAI, where MA and FA represent methylammonium and formamidinium, respectively), and thermal annealing temperatures. Among them, we found that the maximum power conversion efficiency (PCE) was 2.36%, which is significantly higher than the PCE of 0.68% of a reference film without an additive. Machine learning (ML) and statistical analyses revealed significant features and their relationships with TRMC transients, thereby demonstrating the advantages of combining ML and automated experiments for high-throughput exploration of photovoltaic materials.

Reference

[1] C. Nishikawa, R. Nishikubo, F. Ishiwari, A. Saeki, JACS Au 3, 3194 (2023)

[2] A. Saeki, Polym. J. 52, 1307 (2020)
(Invited) Design Strategies of Organic Semiconducting Materials for Organic Photovoltaics
Authors: YunHi Kim
Published: December 2024

Organic solar cells have attracted great attention as next-generation wearable power generators due to their merits of light-weight, low cost, and potential stretchability. One of the most successful advances in improving the power conversion efficiency (PCE) of OSCs has been recently achieved with the advent of non-fullerene small molecule acceptors (NFSMAs). A highly fused backbone structure of the NFSMAs incorporated with strong dye molecules allow to a high absorption coefficient compared to conventional fullerene-based acceptors, leading to the drastic improvement of the light absorption and the PCE of OSCs to 19%. In this presentation, I will discuss the design strategies of Non-fullene acceptors for good stability as well as high efficiency.
High Throughput Solution Combustion Generated Nickel Oxide Films As a Hole Transport Layer for Perovskite Photovoltaics
Authors: Colburn Thomas William , Carbone Abigail , Just Justus , Wainer Ryan , Collinson David William , Dauskardt Reinhold Horst
Published: December 2024

Nickel oxide remains a prominent hole transport layer (HTL) for use in inverted perovskite photovoltaic devices owing to its high optical transmission as a thin film, hole mobility, and chemical tunability. Numerous approaches have been posited for forming high quality nickel oxide thin films with solution combustion synthesis (SCS) as one of the most promising to yield high quality oxide thin films at high throughputs. However, the resulting characterization of the nickel oxide generated can be challenging owing to nickel oxide’s surface reactivity under ambient conditions and its instability against common laboratory techniques such as X-ray photoelectron spectroscopy (XPS) with argon depth sputtering.

Here, we present a multi-modal synchrotron radiation characterizations of nickel oxide thin films generated via solution combustion synthesis with a curing duration of 1 min at 300 ºC for perovskite solar cells. We explore the role of varying the ligand structure and fuel/oxidant ratio of the nickel oxide precursor and assess the resulting properties of the nickel atoms using extended X-ray absorption fine structure, ex situ X-ray absorption near edge spectroscopy, and grazing-incidence X-ray diffraction along with lab-scale XPS. We have also performed some of the first in situ analysis of the combustion process using synchrotron radiation with 5 second time resolution. As a result, we can provide unprecedented sensitivity to correlate between the chemical state of Ni in the film bulk and surface to device performance and stability.
Logic-in-Memory Application of IGZO Channel FET Based 2T0C DRAM
Authors: Kim Ji-Hun , Choi Woo-Tak , Shim Tae-Hun , Park Jin-Sub , Hong Jin-Pyo , Park Jea-Gun
Published: December 2024

IGZO (InGaZnO) channel FET based 2T0C DRAM has attracted extensive research due to back-end-of-line (BEOL) compatibility, low power consumption, and potential for monolithic 3D (M3D) integration. Recent study demonstrated long retention times (> 1000 s), excellent device stability (> 1011) cycles and high density 4F2. However, logic-in-memory applications for 2T0C DRAM has not been reported yet. In this study, we studied the design and implementation of device operations that enable basic logical functions such as AND, OR, NOR, and NAND in 2T0C DRAM.

Fig.1 shows brief fabrication process of IGZO channel FET based 2T0C DRAM. Oxide wafer with 200 nm of SiO2 layer was used for substrate. Then, 20 nm IGZO channel layer was deposited by RF sputtering and W electrodes was formed by DC sputtering for source/drain. Subsequently, 50 nm Al2O3 was deposited by plasma-enhanced atomic layer deposition (PEALD) for gate dielectric, and contact hole was opened by wet etch using diluted BOE (buffered oxide etchant). After that, W electrode was deposited for top gate and storage node. Memory characteristics were measured under operating voltages of 3 V and 2 V for the write-word-line (WWL) and write-bit-line (WBL), respectively.

For the logic operation of the 2T0C DRAM, we designed input voltage pulses that facilitate the AND, OR, NAND, and NOR operation. As shown in Fig.4, storage node voltage (VSN) is initialized by preset operation (cycle 1) and two input signals (cycle 2 and cycle 3) are applied to the WWL sequentially. When high voltage is applied to WWL, write transistor (WTR) is switched on, inducing WBL voltage into the storage node. When low voltage is applied to WWL, storage node maintains previous state regardless of WBL voltage. Following the input sequences, we read output state by measuring drain voltage of RTR, thereby demonstrating the feasibility of AND, OR, NAND, and NOR operations. We will present our approach for logic-in-memory application implementing 16 boolean logic and arithmetic functions such as adder in detail.

Figure 1
Dependency of Skyrmion Size in PMA Structure on Material of Interface Reducing Layer to Generate Skyrmion
Authors: Choi Yohan , Shin Yeon-Soo , Kim Min-cheol , Shim Tae-Hun , Park Jinsub , Park Jea-Gun
Published: December 2024

Abstract

Recently, magnetic skyrmions have been emerged as one of the promising candidates to use information carriers in high density and low power spintronic devices, which potentially be use in memory, logic, and neuromorphic computing due to their nanometer scale small size, non-volatile, and complete linearity [1-2]. Previous studies reported the observation of skyrmion sizes below 100 nm at room temperature [3-4]. However, so far, researches on the size of generated skyrmions depending on the different materials of interface reducing layer have not been discussed.

In this study, therefore, we investigated the dependency of generated skyrmion size in perpendicular magnetic anisotropy (PMA) structures on the material of interface reducing layer (tungsten (W), platinum (Pt), and titanium (Ti)) to generate skyrmion. In addition, We designed a novel PMA structure having an interface reducing layer inserted in between CoFeB free layer and MgO tunnel barrier to generate skyrmions. In particular, the dependencies of the PMA characteristics, including coercivity (Hc), perpendicular anisotropy (Hk), and saturation magnetization (Ms) on the materials (W, Pt, and Ti) and thickness of interface reducing layer were investigated by using a vibrating sample magnetometer (VSM), and magneto-optical Kerr effect (MOKE). Our proposed PMA structures exhibited that Hc was reduced to ~ 5 Oe at the specific thickness of interface reducing layer (W: 0.0804 nm, Pt: 0.1670 nm, Ti: 0.3602 nm), indicating that the skyrmions generated. In addition, it was confirmed that the material of the interface reducing layer strongly influences the size of skyrmions generated in a PMA structure, i.e., 0.0804-nm-thick tungsten generated the skyrmion diameter of 1.23 μm, 0.1670-nm-thick platinum generated the skyrmion diameter of 0.78 μm, and 0.3602-nm-thick titanium generated the skyrmion diameter of 0.84 μm, respectively. We present in detail how Hc, Hk, Ms, and generated skyrmion size were affected by the material of interface reducing layer.

Acknowledgements

This work was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program-Public-private joint investment semiconductor R&D program(K-CHIPS) to foster high-quality human resources) ("RS-2023-00235634", Development of high speed/low power/high reliability 2-terminal field-free SOT-MRAM) funded By the Ministry of Trade, Industry & Energy (MOTIE, Korea)( 1415187787)

References

[1] Nagaosa N. and Tokura Y., Nat. Nanotechnol. 8, 899-911 (2013).

[2] C Back, V Cros et al., J. phys. D. Appl. phys. 53, 363001 (2020).

[3] Aranda A.R. et al. Journal of Magnetism and Magnetic Materials, 465, 471-479 (2018).

[4] Mouad F. et al. Physics Letters A, 384(13), 126260 (2020).

Figure 1
First-Principles Study of Electron-Defect Interaction and Carrier Mobility in Transition Metal Dichalcogenides Semiconductors
Authors: Xiao Zhongcan , Guo Rongjing , Zhang Chenmu , Liu Yuanyue
Published: December 2024

Electron-defect interaction is an important effect limiting the electronic properties of 2D transition metal dichalcogenides (TMD), especially to the low charge carrier mobility. We employ first-principles methods and develop scientific computation software "EDI" (Electron-Defect Interaction), which is used to accurately calculate the scatterings by some common defect types and study the mobility of various TMD systems. Our results indicate that traditional metric of effective mass is not enough to characterize the mobility. But the electron-defect coupling is the most important factor in the systems we research. In addition, we also identify good candidates with high mobility, and provide a potential annealing method to improve the electron transport in TMDs with common vacancy defects.
(Invited) Achieving Erosion Less Designing Cu- and Isolation-Film Polishing-Rate Selectivity in Cu-Film Chemical Mechanical Planarization
Authors: Park Jea-Gun , Kim Pil-su , Jeon Min-Uk , Jin Hyeong-Ju , Ahn Ho-Jun , Kim Ju-Yeon , Park Jin-Hyung
Published: December 2024

Design of logic devices has been scaled down up to several nm (i.e., 5, 4, 3, 2, and 1.8 nm). This scale-down has accompanied a rapid scale-down of the Cu-line width, increasing Cu-line pattern density. The Cu-line formation essentially requires Cu-film CMP, producing the detrimental defects such as dishing, erosion, and edge over erosion (E.O.E) after Cu-film CMP. Particularly, erosion and E.O.E intensively depend on the Cu-line width, and Cu-line pattern density, degrading device operating speed and yield. However, erosion and E.O.E have not been reported clearly.

In this study, unlike conventional Cu-film CMP slurries, for achieving erosion- and E.O.E-less in nanoscale Cu-line pattern CMP, 1-step Cu-line CMP process was designed using a Cu bulk CMP slurry performing remarkably high polishing-rate via surface chemical oxidation layer formation using halide oxidant (i.e., H5IO6) and a Cu barrier-metal (BM) slurry conducting hindrance layer formation using inhibitor (i.e., BTA). Using designed Cu bulk and BM slurries with 100-nm-diameter colloidal silica abrasives could achieve erosion-less for the Cu-line pattern density of 5 ~ 55%, but a high amount of E.O.E remained for all Cu-line pattern density after CMP, as shown in Fig. 1. Thus, the dependencies of erosion and EOE on polishing-rate selectivity between Cu- and Isolation-films were investigated for achieving both erosion- and EOE-less. In our presentation, we will prove the mechanism of the selectivity on Cu- and Isolation-film. In addition, we will present the dependencies of the chemical dominant polishing properties (i.e., OH radical, chemical oxidation degree of the Cu- and Isolation-film surface, chemical composition of chemical oxidation, slurry absorption degree, and corrosion potential and current) as well as the mechanical dominant polishing properties (i.e., electrostatic force between abrasives and Cu- and Isolation-film surface) on the inhibitor concentration.

Acknowledgment

This research was supported by the MOTIE(Ministry of Trade, Industry & Energy (1415180388) and KSRC(Korea Semiconductor Research Consortium) (20019474) support program for the development of the future semiconductor device, and by the Brain Korea 21 PLUS Program and the Samsung Electronics’ University R&D program.

Figure 1
Good Thermal Stability in Dielectric Properties of (1-x)(K0.8Na0.2)NbO3-xSrTiO3 Ceramics for the Application to X9R MLCC
Authors: Kwak San , Kim In-Su , Lee Geun-Soo , Min Byeong-Jae , Nahm Sahn
Published: December 2024

(1 − x)(K0.8Na0.2)NbO3–xSrTiO3 [(1 − x)(K0.8N0.2)N–xST] ceramics are well sintered at 1120 – 1200 ˚C for 2 h. The Curie temperature (T
C) and the orthorhombic–tetragonal phase transition temperature (T
O–T) of the ceramics considerably shifts toward low temperature region and the T
C peak is flattened with increasing amount of x. Moreover, the ceramics (x ≥ 0.09) show relatively large relaxor ferroelectric properties. The 0.9(K0.8N0.2)N–0.1ST ceramics exhibit a remarkable thermal stability in dielectric properties, and it complies with the requirement of the EIA standard X9R multilayer ceramic capacitor (MLCC) specification. However, the (1 − x)(KyN1 − y)N−xST ceramics (x = 0.10, 0.0 ≤ y ≤ 0.6), which contain relatively large amount of Na+ ions, cannot satisfy the requirement of the X9R MLCC specification, because they have relatively small relaxor ferroelectric properties and the reduced decreasing rate of the T
C. An 11 layered MLCC is fabricated by using the 0.9(K0.8N0.2)N–0.1ST ceramic. The fabricated MLCC also complies with the requirement of the X9R MLCC specification with an excellent stability to the applied electric field. Therefore, the 0.9(K0.8N0.2)N–0.1ST ceramic can be one of the excellent dielectric ceramic materials for the application to X9R MLCC devices.
Utilizing the Effect of Chalcogen Atoms in Carbazole Based SAM for Achieving High Efficiency in Inverted Perovskite Solar CELLS
Authors: Lee Dongmin , Kim Dong Suk
Published: December 2024

In the realm of inverted perovskite solar cells (PSCs), self-assembled monolayers (SAMs) have emerged as a prominent choice for the hole-selective layer (HSL). Apart from their role in tailoring electrical characteristics, the molecular engineering of SAMs offers a pathway to mitigate buried defects in perovskite materials. Here, we proposed a targeted strategy for passivating buried defects through the chalcogen effect, achieved by introducing the sulfur heteroatom. The sulfur atoms within in (4-(3,6-bis(methylthio)-9H-carbazol-9-yl)butyl)phosphonic acid (MeS-CzC4PA) possess the ability to form coordination bonds with Pb2+ ions, effectively mitigating defects at the buried interface. As a result, the PSCs based on MeS-CzC4PA show a PCE of 24.2%, primarily attributed to a significant increase in the fill factor (FF). Insights gained from this molecular design approach will propel the development of advanced functional SAM HSLs, thereby augmenting the efficiency of PSCs.
Nano- and Mesoporous Structure Formation Probed with in Situ/in Operando Small and Wide-Angle X-Ray Scattering Analysis during Electrodeposition and Dealloying Processes
Authors: Amenitsch Heinz , Wieser Philipp Aldo
Published: December 2024

Electrochemical formation of nanoporous materials by electrodeposition or dealloying is essential in various fields such as catalysis, energy storage, and sensing due to their high surface areas and controlled pore sizes. Understanding the underlying principles leading to specific morphologies during the electrochemical protocol is of importance for a directed design of desired morphologies. In situ/in operando analysis at the nanoscale, such as grazing incidence small and wide angle X-ray scattering (GISWAXS), is an important tool to understand the pathway of the structure evolution at both the mesostructural and the crystalline levels. Here the development of a versatile electrochemical cell for GISWAXS [1] was essential to be able to investigate such processes.

In this presentation an overview of various projects utilizing GISWAXS is given: (i) dealloying of the binary systems AgAu and CoPd [2]; electrodeposition of (ii) vertical aligned hexagonal Pt films using liquid crystal templating with Brij®56 [3]; and (iii) mesoporous platinum nickel films using Pluronic P123 as structure directing agent, as proposed by [4]. Additionally, some current highlights in the field of electrodeposition of ordered materials will be presented.

M. Bogar, I. Khalakhan, A. Gambitta, Y. Yakovlev, H. Amenitsch, In situ electrochemical grazing incidence small angle X-ray scattering: From the design of an electrochemical cell to an exemplary study of fuel cell catalyst degradation. J. Power Sources. 477, 229030 (2020).

Gößler, E. Hengge, M. Bogar, M. Albu, D. Knez, H. Amenitsch, R. Würschum, In Situ Study of Nanoporosity Evolution during Dealloying AgAu and CoPd by Grazing-Incidence Small-Angle X-ray Scattering. J. Phys. Chem. C. 126, 4037–4047 (2022).

P.A. Wieser, D. Moser, B. Gollas., H. Amenitsch, Monitoring of Pore Orientation by in Operando Grazing Incidence Small-Angle X-ray Scattering during Templated Electrodeposition of Mesoporous Pt Films, Acs Appl. Materials and Interfieces 15, 47604-47614 (2023).

K. Eiler, S. Surinach, J. Sort, E. Pellicer, Mesoporous Ni-rich Ni–Pt thin films: Electrodeposition, characterization and performance toward hydrogen evolution reaction in acidic media, Applied Catalysis B, Environmental 265, 118597 (2020).

Fig. 1 (a) Scheme of the experimental setup for monitoring electrodeposition of mesoporous PtNi via in operando GISWAXS. The incoming X-ray beam impinges on the sample at a glancing angle αi
(shown in the zoomed inset into the electrochemical cell). The scattering intensity is recorded simultaneously by two detectors: one in the direct beam, to study the GISAXS pattern during electrodeposition, and the other in the GIWAXS regime to resolve the diffraction pattern. (b) Chronoamperometric data during electrodeposition, performed under constant potentials at - 0.7 V vs AgCl. (c) Exemplary SEM micrograph of resulting mesoporous PtNi film.

Figure 1
Gallium Nitride Electrodeposition at Indium Tin Oxide and Fluorene Tin Oxide Electrodes in Ammonium Nitrate and Gallium Nitrate Aqueous Solution: New Findings
Authors: Leyva Aranzabal Mauricio A. , Cabrera Carlos R.
Published: December 2024

In several power electronics applications, gallium nitride (GaN) has established itself as a competitive alternative to silicon. However, the pricey growing epitaxial processes used in present GaN deposition procedures highlight the need for more accessible and alternative deposition methods. This study compared the use of indium tin oxide (ITO) and fluorine tin oxide (FTO) electrodes from a solution containing 0.1 M gallium nitrate (Ga(NO3)3) and 2.5 M ammonium nitrate (NH4NO3). Gallium nitride thin films were synthesized by potentiostatic electrochemical deposition (PECD). Chronoamperometry (CA) was used to start the ITO and FTO thin film investigation at various time scales, from one hour to four hours, and with a constant applied potential of -1.7 V vs. Ag/AgCl (Saturated KCl). Characterization methods showed that the electrode and PECD durations were related to the characteristics of the GaN thin film. The films crystallized in the wurtzite hexagonal structure in accordance with the 33o, 36o, and 46o X-Ray Diffraction (XRD) peaks. The impacts of deposition duration on the morphology and structure have a dependence on growing time, as shown by scanning electron microscopy (SEM) analysis. Grain boundaries of varying sizes on ITO and uniform particles formed on FTO, respectively, beginning at two hours PECD. The coexistence percentages of gallium (Ga) and nitrogen (N) in these plate-like films were determined by means of energy dispersive spectroscopy. After four hours, the largest Ga weight percentage was found on FTO at 65%, and after two hours, on ITO at 10%. The mixed phonon modes of hexagonal and cubic GaN were detected in the Raman spectra.
Gold and Gold Alloys Electropolishing Using HCl-Glycerol-Ethanol Electrolytes
Authors: Rodriguez Julymar , Doche Marie-Laure , Hihn Jean-Yves
Published: December 2024

Electropolishing (EP) is an electrochemical process used in the final stage of metal processing to reduce surface roughness and enhance functional, technical, and aesthetical properties. Some of its advantages are the preservation of surface metallurgical properties and the ability of treating complex geometries.

EP is based on a homogeneous dissolution of the surface, driven by a competition between oxidation reactions and dissolution. Compounds such as cyanides and thiourea, which was now classified as a classed 3 carcinogen, can form very stable soluble complex with precious metals like gold and its alloys. Consequently, they have been widely used in the formulation of EP electrolytes for these materials, but their toxicity has led to the research of alternative solutions.

This work presents a study based on a cyanide and thiourea free electrolyte previously reported in the literature for pure gold electropolishing and composed by hydrochloric acid, glycerol, and ethanol1,2. The aim was to give new insights in the involved mechanisms to evaluate the electrochemical behavior and the influence of different parameters on pure gold, and to extend this process to 18k jewelry gold alloys (yellow, rose, red and gray). In the first part of the study, only two of the electrolyte components (HCl-glycerol) were used to study the influence of chloride concentration on pure gold EP. Electrochemical techniques and surface properties analysis were evaluated.

In the second part, the effects of adding ethanol to electrolyte composition and of variating rotation speed were also evaluated on pure gold. The best results were obtained for a HCl 50%vol. - Glycerol 25%vol. - Ethanol 25%vol. electrolyte at a rotation speed of 1000 rpm. This solution was then used to electropolish 18K gold alloys. Mitigated results were obtained for silver-containing alloys (yellow, rose and red), which were not uniformly polished due to the formation of an AgCl film on the surface that partially masks the substrates, whereas better results were obtained with 18K grey gold3.

(1) Peck, W. F.; Nakahara, S. Preparation and Electropolishing of Thin Gold Disc Specimens for Transmission-Electron-Microscope Examinations. Metallography 1978, 11 (3), 347–354. https://doi.org/10.1016/0026-0800(78)90047-2.

(2) Verlinden, J.; Celis, J. P.; Roos, J. R. Passivation-depassivation behaviour of gold in a hcl-glycerol solution and its application to electropolishing. Thin Films Sci. Technol. 1983, 341–346.

(3) Rodriguez J. ; Doche M-L ; Hihn J-Y ; Electropolishing of gold and gold alloys in HCl-glycerol-ethanol electrolytes App. Surf. Sci. Adv. 21(2024) 100604 https://doi.org/10.1016/j.apsadv.2024.100604
(Invited) Mn-Based High-Energy Cathodes for Lithium-Ion Batteries
Authors: Chen Guoying
Published: December 2024

Cation-disordered Li-excess rocksalts (DRX) are promising cathode materials for next-generation lithium-ion batteries utilizing sustainable resources. [1] These compounds are typically Co- and Ni-free, and they offer exceptionally large charge storage capacities by activating the redox reactions of both cationic transition-metals and anionic oxygen in the lattice. [2-4] Recent studies showed that significant performance improvement can be achieved by introducing fluorine substitution. Fluorine was found to improve local structural stability and chemomechanical properties, as well as reduce oxygen gas release, impedance rise and capacity fade. [5-7] However, achieving adequate cycle life remains a formidable barrier in DRX cathodes.

In this presentation, we will show our recent effort in developing stable DRX oxyfluorides based on Mn-redox chemistry. Mn-rich DRX oxyfluoride cathodes consisting of earth-abundant elements will be presented. These materials experience unique local structural transformations upon charge and discharge, leading to dynamic evolution in voltage profile and significant capacity rise during early cycles. Stable cycling can be achieved after the initial activation process. Our understanding in how chemistry can impact local and long-range structures and their evolution during electrochemical cycling will also be presented, as well as the perspectives on future directions in cathode development.

References

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Yabuuchi, N.; Takeuchi, M.; Nakayama, M.; Shiiba, H.; Ogawa, M.; Nakayama, K.; Ohta, T.; Endo, D.; Ozaki, T.; Inamasu, T.; Sato, K.; Komaba, S., High-Capacity Electrode Materials for Rechargeable Lithium Batteries: Li3NbO4-based System with Cation-Disordered Rocksalt Structure. Natl. Acad. Sci.
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Chen, D.; Kan, W. H.; Chen, G. Understanding Performance Degradation in Cation-Disordered Rock-Salt Oxide Cathodes. Energy Mater.
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Lee, J.; Papp, J. K.; Clément, R. J.; Sallis, S.; Kwon, D.-H.; Shi, T.; Yang, W.; McCloskey, B. D.; Ceder, G. Mitigating oxygen loss to improve the cycling performance of high capacity cation-disordered cathode materials. Commun.
2017, 8, 981.

Lun, Z.; Ouyang, B.; Kitchaev, D. A.; Clément, R. J.; Papp, J. K.; Balasubramanian, M.; Tian, Y.; Lei, T.; Shi, T.; McCloskey, B. D.; Lee, J.; Ceder, G. Improved Cycling Performance of Li-Excess Cation-Disordered Cathode Materials upon Fluorine Substitution. Energy Mater.
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Ahn, J.; Chen, D.; Chen, G.. A Fluorination Method for Improving Cation-Disordered Rocksalt Cathode Performance. Energy Mater.
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