bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Activated Si-Si Wafer Bonding Using Different Ion Species
Authors: Danner Matthias , Rebhan Bernhard , Kerepesi Péter , Werner Wolfgang S. M. 
Published: February 2024

Surface activated bonding (SAB) on wafer level is enabled by the EVG ComBond® system for irradiation with different ion species. In this process, the native oxide of 200 mm Si wafers is sputter-removed, and an amorphous layer is generated. After ion treatment, the wafers are bonded in ultra-high vacuum (UHV) at room temperature. The impact of Ar, Kr and Xe ion irradiation on the amorphous layer thickness (ALT) was investigated with the goal of optimizing the bonding process. This was i.a. motivated by the fact, that the presence of an amorphous layer reduces the electrical conductivity across the wafer interface [1].
The ALT of unbonded wafers was evaluated via spectroscopic ellipsometry (SE) for varying ion species, ion energies and angles of incidence. The results show that heavier ions generate a thinner amorphous layer than light ions (see Fig. 1). This is most likely due to the higher scattering cross section of heavy ions resulting in a lower penetration depth. For each ion type there is a minimum in the ALT as a function of the ion energy which can be attributed to sputter-implantation dynamics. Furthermore, the ALT is decreasing with the angle of incidence as the incoming ions are projected into the material.
Transmission electron microscopy (TEM) measurements were conducted on bonded wafer pairs and confirm the trend of heavy ions generating a thinner amorphous layer. Moreover, the TEM measurements show that post-bond annealing at 450°C for 5 h reduces the ALT due to recrystallization near the bonding interface.
To ensure mechanical stability for further wafer processing and for the final device, bonding energy measurements were conducted via the Maszara method [2]. Although maximum bonding energy can be achieved for specific parameters with each ion species, Xe irradiated samples tend to have a higher overall bonding energy.
[1] P.A. Stolk et al., “Contribution of defects to electronic, structural, and thermodynamic properties of amorphous silicon”, in Journal of Applied Physics, vol. 75, no. 11, pp. 7266-7286 (1994).
[2] W.P. Maszara et al., “Bonding of silicon wafers for silicon-on-insulator”, in Journal of Applied Physics, vol. 64, no. 10, pp. 4943-4950 (1988).

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(Invited) Deformation of 2D Semiconductors By Interfaces with Organic Materials
Authors: Kiriya Daisuke 
Published: February 2024

2D semiconducting materials gather attention for realizing atomically thin optoelectronic devices and a platform for emerging quantum phenomena. Especially monolayer 2D materials are fascinating because of their ultrathin crystalline structure with various physicochemical characteristics such as direct-band gap and asymmetric crystalline structures. In this presentation, I will show our recent results related to the deformation of transition metal chalcogenides (TMDCs) morphology by interfaces with organic materials.
The mechanical exfoliation method is a simple method to prepare TMDCs and has been widely applied in many research studies. However, the exfoliated TMDCs on substrates show a bunch of bulk flakes and very few target monolayers. In the worst case, the exfoliated monolayer is surrounded by bulk flakes and is difficult to apply for fabricating devices. We developed a method of selectively removing bulk flakes, furthermore, isolating monolayer TMDCs on substrates. The method uses ultrasonication in organic solvents with a consideration of surface chemistry. Surprisingly, bulk flakes are selectively removed, and the adjacent monolayers can be effectively isolated on substrates. [1]
Monolayer TMDCs show emission properties because of their direct-band gap nature. The emission strength, e.g., photoluminescence (PL) intensity, is often low. The limitation factor includes various parameters, for example, the over-carrier concentration is one limiting factor in sulfur-based compounds (MoS2 and WS2). So far, p-type doping to reduce the electron concentration is demonstrated to enhance their PL intensity, however, the method is not applicable to selenium-based compounds, such as MoSe2 and WSe2. In addition, a universal method to enhance PL intensity for the selenium-based compounds is still few. We found a general PL enhancement method for both sulfur- and selenium-based compounds, MoS2, WS2, MoSe2, and WSe2, by applying a hydrocarbon, paraffin. The method simply uses paraffin on the surface of TMDCs. I would show the details of the results and methods in the presentation. [2]
REF:
[1] T. Nakamoto, et al., " Selective isolation of mono to quad layered 2D materials via sonication-based solution engineering", ChemRxiv, 2022, DOI: 10.26434/chemrxiv-2022-lgp8l
[2] T. Nakahara, et al., " Spontaneous crystal fluctuation in hydrocarbon polymer–coated monolayer MoS2, MoSe2, WS2, and WSe2 with strong photoluminescence enhancement", ChemRxiv, 2023, DOI: 10.26434/chemrxiv-2023-gxzqw
Quantifying the Thermochemistry of Kinetic Transitions in a Solid-State Charged Li/Llzo/LCO Cell Using Differential Scanning Calorimetry
Authors: Bhargava Bhuvsmita , Johnson Nathan B , Zaman Samaa , Albertus Paul 
Published: February 2024

It is a general understanding that removal of combustible organic solvent with the introduction of solid-state electrolytes would make a battery safer. However, safety in solid state batteries is multifaceted and involves analysis of self-heating rates, total generated energy, thermal runaway onset temperature, maximum temperature, and thermal runaway prevention mechanisms1,2. The use of reactive lithium metal as the anode, and cathode material such as LiCoO2 that releases O2 when heated in its delithiated state, results in conditions in which the exothermic reaction 4Li+O2→2Li2O may occur if these reactants come into contact. We measure heat flow data using a differential scanning calorimeter (DSC) and hermetically sealed DSC pans to establish a reaction thermochemistry responsible for self-heating of LixCoO2|LLZO|Li metal cell, with x=0.43 (which corresponds to 4.3V vs. Li). While the main exothermic reaction is 4Li+O2→2Li2O when only Li0.43CoO2 is present in the cathode3, a practical solid-state cathode will almost certainly contain conductive carbon and a fluorinated binder. We carry out careful DSC analysis with a range of components and ratios of components to quantify the expected reaction pathway, and amount of heat released, for a cathode that contains Li0.43CoO2, carbon additive, and PVDF binder. We find that the carbon and PVDF strongly influence the reaction pathway upon heating to 500°C in our DSC experiments. Hence, the presence of even small weight fraction components in a solid-state cathode should be considered when evaluating their thermochemistry upon heating.
References:
(1) Bates, A. M.; Preger, Y.; Torres-Castro, L.; Harrison, K. L.; Harris, S. J.; Hewson, J. Are Solid-State Batteries Safer than Lithium-Ion Batteries? Joule
2022, 6 (4), 742–755. https://doi.org/10.1016/j.joule.2022.02.007.
(2) Johnson, N.; Albertus, P. Modeling Thermal Behavior and Safety of Large Format All-Solid-State Lithium Metal Batteries under Thermal Ramp and Short Circuit Conditions. J. Electrochem. Soc.
2022, 169 (6), 060546. https://doi.org/10.1149/1945-7111/ac79cf.
(3) Inoue, T.; Mukai, K. Are All-Solid-State Lithium-Ion Batteries Really Safe?–Verification by Differential Scanning Calorimetry with an All-Inclusive Microcell. ACS Appl. Mater. Interfaces
2017, 9 (2), 1507–1515. https://doi.org/10.1021/acsami.6b13224.
(Invited) Culprits or Collateral Damage? The Science behind Lithium-Ion Battery Failure Investigations
Authors: Spray Ryan , Barry Michael , Hayes Troy 
Published: February 2024

Thermal runaway failures of lithium-ion batteries have garnered a great deal of attention in recent years, including notable failures in the spaces of consumer products, electric vehicles, and energy storage systems. The growing public awareness of hazards associated with thermal runaway in lithium-ion batteries has coincided with increased scrutiny of lithium-ion batteries when they are found at fire scenes. Lithium-ion batteries can go into thermal runaway due to heating from an external fire, even if they are not the cause of the fire. As always, the fire investigator and other experts involved in the failure analysis need to remain guided by the scientific method when performing an origin and cause analysis, including when that analysis involves lithium-ion batteries.
This presentation will encompass many of the tools and reasoning that may be relied upon when analyzing the role lithium-ion batteries at fire scenes, as well as in the post-scene analysis of batteries and battery-containing devices. Techniques for understanding heat release and heat release rate during thermal runaway failures will be discussed, as well as the associated literature that may be relied upon to estimate heat release based on chemistry and capacity of the cells in question. Also to be discussed are metallurgical approaches and techniques that may inform the conditions that likely existed during the failure of the battery.
Deconvoluting the Impact of Early-Life Abuse Conditions on the Cyclic Degradation of Lithium-Ion Cells
Authors: Leonhardt Robert , Tichter Tim , Scharpmann Luca , Schmidt Anita , Krug von Nidda Jonas 
Published: February 2024

The successful repurposing of degraded lithium-ion (Li-ion) batteries in second-life applications is a vital step towards achieving a circular economy. While reusing aged Li-cells is a promising way of mitigating their overall environmental footprint, it is crucial to anticipate their future safety and performance characteristics. Unfortunately, predicting these properties is a cumbersome task, essentially caused by limited knowledge of the interference of different degradation modes in the cells’ first life.
To still enable estimating of these parameters from a current state, the present study systematically investigates the impact of abusive conditions in an early phase of the cells’ life on their subsequent degradation behavior. For this purpose, individual Li-cells are initially stressed by different measures such as overcharging, deep-discharging, plating, and deliberate combinations of the aforementioned methods. Electrochemical performance indicators are monitored during subsequent cycling of the cells which provides insights into the interdependencies of different degradation modes induced by specific stress conditions. In this manner, it is clarified whether or not the total degradation can be determined by a convolution or a superposition of individual deterioration effects and, thus, be described as a multidimensional state function.
This knowledge will finally contribute to a better understanding of the performance and safety behavior of degraded Li-ion batteries which can help to successfully implement them into second-life applications.
Synchrotron X-Ray Topography Studies for Defect Formation at the Early Stage of PVT-Grown 4H-SiC Crystals
Authors: Hu Shanshan , Liu Yafei , Cheng Qianyu , Chen Zeyu , Raghothamachar Balaji , Dudley Michael 
Published: February 2024

Silicon Carbide (SiC), typically 4H-SiC, is replacing conventional silicon materials for high power and high frequency applications due to its excellent electrical and thermal properties [1]. However, high quality SiC wafers with low defect density are still in urgent need for automotive and energy saving applications. SiC wafers are obtained from bulk growth by physical vapor transport (PVT) method and considerable efforts have been expended to optimize growth process to lower defect densities. One major approach is the study of initial stages of crystal growth as most defects are nucleated at this stage and propagate into the boule. Ailihumaer et al [2] demonstrated the behaviors of threading edge dislocations (TEDs), threading screw dislocations (TSDs)/threading mixed dislocations (TMDs), and basal plane dislocations (BPDs) across the seed/newly grown layer interface in PVT-grown 4H-SiC. Sanchez et al [3] revealed the nucleation of TEDs and TSDs at the initial growth stage in PVT-grown SiC.
However, more detailed investigations are still in demand for PVT grown 4H-SiC crystals during initial stage of growth. This study investigates 4° off-axis 4H-SiC wafers with several hundred microns of initial-stage growth PVT method. Synchrotron X-ray topography (SXRT) technique is employed and shows dramatically modified defect distribution across the seed/newly grown layer interface (Figure 1). The formation of Shockley stacking fault starting at initial stage of crystal growth is suggested as partial dislocations running along <11-20> directions on basal plane are observed to form rhombus shapes (Figure 2). Prismatic slip is observed to take place near the wafer edges and prismatic dislocations undergo cross slip to form unique dislocation configurations. A statistical analysis on defect changes across the seed/newly grown layer is being carried out and the results will be reported. These results will be complemented by observations from Nomarski optical microscopy (NOM) and Raman Spectroscopy studies to propose the formation mechanism of defects across the seed/newly grown layers.
References:

G. Dhanaraj, K. Byrappa, V. Prasad and M. Dudley, Springer handbook of crystal growth, edn. (Springer, 2010)

T. Ailihumaer, H. Peng, Y. Liu, B. Raghothamachar, M. Dudley, G. Chung, I. Manning and E. Sanchez, J. Electron. Mater., 50, (2021).

E. Sanchez, J. Liu, M. De Graef, M. Skowronski, W. Vetter and M. Dudley, J. Appl. Phys., 91, (2002).

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(Invited) Challenges and Opportunities for the Computational Analysis of Electrochemical Energy Systems
Authors: Secanell Marc 
Published: February 2024

Electrochemical systems are challenging to analyze and design due to their multi-dimensional, time-dependent, and multi-physics nature. For this reason, many computational electrochemical system models have been developed in the past three decades, some of which can now be found in commercial software packages, e.g., COMSOL or ANSYS Fluent. These models however: i) are based on simplifying assumptions, e.g., reduced dimensionality, infinite dilution, Tafel kinetics; ii) contain uncertain input parameters, e.g., effective transport properties and kinetic parameters; and, iii) are only validated with a limited number of experiments, e.g., polarization curves. These limitations, understandable at the time due to limited computational resources, characterization techniques, and material understanding and stability, are difficult to justify today that parallel programming and computer clusters enable scientists to perform large multi-dimensional simulations; electrochemical testing has expanded to include segmented cell testing, impedance spectroscopy, water flux estimation, and in-operando visualization; and, characterization tools and techniques have been developed to, for example, easily measure adsorption isotherms, effective proton conductivity and, within a given resolution, visualize the three-dimensional microstructure of the electrodes.
Scientists working on computational analysis of electrochemical systems must acknowledge that further model development is still needed and must take advantage of new resources to improve the robustness and accuracy of cell-level models. The path is long and crooked, but it is very likely that the opportunity for a truly useful computational model, one that can be used for design, is beyond simplistic implementations and polarization curves. The effort is great, but it can be minimized by concurrent software development, as well as, by careful experimental work dedicated to parameter estimation and model validation.
This presentation aims at outlining the limitations of state-of-the-art models, the challenges and opportunities of concurrent development and maintenance of a multi-scale, transient electrochemical energy system software, such as the open-source fuel cell simulation toolbox (OpenFCST) [1], and the new opportunities provided by combining advanced characterization tools with computational analysis. As an example, the development and validation of the transient, two-phase fuel cell and electrolyzer cell-level models in OpenFCST will be discussed [2]. The use of a hydrogen-pump model to study the effect of an active catalyst in CL effective proton conductivity measurements will also be discussed as an example of concurrent experimental/model design [3].

References

[1] M. Secanell et al., ECS Transactions 64.3 (2014) (10.1149/06403.0655ecst)
[2] M. Moore et al, Journal of the Electrochemical Society (2023) (10.1149/1945-7111/acc898)
[3] M. Mandal et al, ACS Applied Materials & Interfaces, 12 (44), 49549-49562 (2020) (10.1021/acsami.0c12111)
Numerical Reconstruction of Proton Exchange Membrane Fuel Cell Gas Diffusion Layers
Authors: Yang Danan , Garg Himani , Beale Steven B. , Andersson Martin 
Published: February 2024

Flooding and dehydration reduce stability and power performance in Proton Exchange Membrane Fuel Cells (PEMFCs). The Gas Diffusion Layer (GDL) plays a crucial role in facilitating reactant gas transport and removing product water from the electrode. To suit various PEMFCs, GDLs with different shapes have been commercialized. The impact of the GDL structure on the surface-tension-driven water transport behavior remains poorly understood. However, this is one important aspect that can be controlled by proper design. In this study, the GDL performance is investigated by comparing curved and straight carbon fibers within the region. Specifically, an image-processing method extracts porosity, domain size, and fiber diameter from an experimental image-based GDL reconstruction. These parameters are utilized by in-house developed computer codes to stochastically reconstruct curved and straight carbon fiber GDLs, respectively. The real and reconstructed GDLs are compared in terms of pore size distribution, tortuosity, and permeability. Liquid transport in these GDLs and corresponding gas channels is simulated using a volume of fluid method in OpenFOAM 7.0.
Figure 1(a) presents the T-shaped simulation domain and top view of three GDLs. Figure 1(b) displays the Cumulative Density Function (CDF) of the pore size distribution for the three GDLs, revealing that the main difference between the three GDLs lies in the pore diameter range of 10-30 µm. Upon completion of the research program, we aim to identify the influence of fiber shape on the GDL transport properties as well as the water behavior inside them.

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Numerical Simulation of the Two-Phase Flow Dynamics in an Alkaline Water Electrolyzer Considering Difference in Bubble Diameter
Authors: Kanemoto Ryo , Araki Takuto , Mitsushima Shigenori 
Published: February 2024

For more efficient hydrogen production, predicting the characteristics of bubble flow inside a water electrolyzer is critical since bubbles affect ion transport, and electrode coverage by bubbles influence overpotentials and the entire electrolysis performance. Transport of bubble significantly depends on its size. In this study, a CFD model of an alkaline water electrolyzer which considers difference in sizes of generated bubbles was developed. The model treats bubbles of different sizes as different gas phases, which are independent of each other. The total bubble mass source for a given current density is divided into phases of each bubble size according to experimental visualizations. Drag, virtual mass, lift, wall lubrication, and turbulent dispersion forces are considered as interaction between gas and liquid phase.
The following three sizes of bubbles were considered: diameters d = 36 μm (small), 75 μm (medium), and 208 μm (large). The entire calculation domain represents the anode side of a zero-gap monopolar alkaline water electrolyzer. Figure 1 shows the volume fraction fields of the three gas phases (i.e., bubble sizes) at a constant current density of 0.6 A/cm2. The bubbles are generated on the electrode surface at the z=0 plane. As the liquid phase forms a circulating flow inside the electrolyzer, small bubbles are transported along the circulating downstream flow due to smaller buoyancy force compared to their viscous drag. In contrast, large bubbles flow out directly to the upper outlet because buoyancy force dominates. This result points out the need to consider the difference in bubble diameter for designing flow field inside alkaline water electrolyzer.
[Acknowledgements]
This study was based on results obtained from the Development of Fundamental Technology for Advancement of Water Electrolysis Hydrogen Production in Advancement of Hydrogen Technologies and Utilization Project (P14021) commissioned by the New Energy and Industrial Technology Development Organization (NEDO).
Fig. 1. Total gas phase volume fraction field obtained from the sum of the volume fraction field for each size bubble, and its experimental visualization.

Figure 1
Gas Diffusion Electrode for Oxygen Evolution Reaction Catalyst Testing
Authors: Puthiyapura Vinod Kumar , Zalitis Christopher Mark , Stevens James 
Published: February 2024

The oxygen evolution reaction (OER) is one of the major contributors of efficiency loss in water electrolysis and consequently, development of OER catalysts to improve the electrolyser efficiency is a major reasearch theme in the field. Though the current commercial PEMWE may operate at anode potential <1.60 V, futue PEMWE may operate at potential higher than this as the drive to operate PEMWE at high current density is inceasing. Inorder to achieve this, an active and stable catalyst is required that can operate at this regime. Also, the potential experienced by the anode during the startup/shutdown of an electrolyser are different to the steady state value.
Conventional OER testing involves catalysts coated on a conductive substrate submerged in an electrolyte solution, in a three electrode cell. However, such techniques are generally limited to low current densities due to oxygen bubble formation and site blocking at high current density limiting the system to study the OER kinetics below realistic operating current density. Although Rotating Disk Electrode(RDE) is widely employed to mitigate this, the RDE system is still not effective enough to remove the bubbles1.
A floating electrode system developed by Kucernak et al2 shows that combining direct access with a lower catalyst loading improves the O2 gas mass transport and a higher current density could be achieved for the ORR. This technique also used for OER by Arenz et al.3, for easier bubble removal. Combining these two above mentioned systems, we have developed a new GDE cell system which allows screening of OER catalyst at industrially relevant current densities. This cell allows to study the OER kinetics at very realistic voltage/current regime and the information obtained helps to develop more active/stable catalyst.
The OER catalyst diagnostics test from our GDE cell was comparable to the standard three electrode cell with an additional advantage of extended potential window upto 1.80 V vs.RHE. Preliminary results obtained from our study shows a promising opportunity to study the OER at high current densities.
Reference

FathiTovini, A.Hartig-Weiß, H.A.Gasteigerand, H.A.El Sayed, Journal of The ElectrochemicalSociety, 2021, 168, 014512.

M.Zalitis,D.KramerandA.R.Kucernak,Phys.Chem.Chem.Phys.,2013,15,4329-4340

Schröder,V.A.Mints,A.Bornet,E.Berner,M.FathiTovini,J.Quinson,etal., JACS Au 2021,1(3),247-25