bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protective Coating Layers via Phosphazene Compounds for Stabilizing Silicon Anode Materials
Authors: Ghaur Adjmal , Peschel Christopher , Dienwiebel Iris , Haneke Lukas , Du Leilei , Profanter Laurin , Placke Tobias , Winter Martin 
Published: July 2022

In recent years, lithium-ion batteries (LIBs) are widely used in electric vehicles (EVs) and mobile energy storage devices (ESDs), which has led to higher requirements for energy density. To fulfill these requirements, tremendous attention has been paid to design advanced LIBs with various silicon active materials as alternative negative electrodes to replace graphite (372 mAh g-1) due to their high theoretical gravimetric capacity (4200 mA h g-1).[1,2] However, silicon as potential anode material suffers from huge volume changes during charging and discharging and has a poor electronic conductivity which negatively impacts the long-term performance and prevents high silicon contents from practical application.[3] Additionally, an unstable crystalline silicon structure tends to pulverization during the (de)lithiation process.[4] To compensate the volume changes, alleviate pulverization and maintain high electronic conductivity, silicon-doped graphite composites with protecting coating layers are a promising approach. In this context, phosphazene compounds are investigated concerning their silicon protecting properties in silicon-doped graphite composites. In detail electrochemical performance measurements in pouch full-cells (NCM523||SiOx/C), supressing gas formation properties and post-mortem analyzes were carried out to characterize phosphazene compounds as additive materials. The introduction of the dual-additive approach in state-of-the-art electrolytes leads to synergistic effects between FEC and phosphazene compounds which accelerate the durability of silicon particles and results in enhanced electrochemical performance.

Reference:

[1]Zuo X, Zhu J, Muller‐Buschbaum P, Cheng Y, Silicon based lithium‐ion battery anodes: a chronicle perspective review, Nano Energy, 2017, 31, 113‐143.
[2]Jimenez A. R., Klöpsch R., Wagner R., Rodehorst U. C., Kolek M., Nölle R., Winter M., Placke T., A step toward high-energy silicon-based thin film lithium ion batteries, ACS Nano, 2017, 11, 5, 4731-4744.
[3] Berla A. L., Lee S. W., Ryu I., Cui Y., Nix W. D., Robustness of amorphous silicon during the initial lithiation/delithiation cycle, Journal of power sources, 2014, 258, 253-259.
[4] Casimir A., Zhang H., Ogoke O., Amine J. C., Lu J., Wu G., Silicon-based anodes for lithium-ion batteries: Effectiveness of materials synthesis and electrode preparation, Nano Energy, 2016, 27, 359-376.
Advanced Data-Driven Modeling Framework for Predicting Thermal Failures in Li-Ion Pouch Batteries
Authors: Mastrogiorgio Massimiliano , Das Goswami Basab Ranjan , Ragone Marco , Mashayek Farzad , Yurkiv Vitaliy 
Published: July 2022

With the rapid development and widespread applications of lithium-ion batteries (LIBs), there is an ongoing need to extend and apply theoretical models that assist LIB’s safety aspects. It is particularly important for electric vehicles (EVs) due to numerous recent fire accidents. Thermal runaway (TRA) is one of the principal causes of LIB’s failures in EVs occurring due to thermal or mechanical breakdown, internal/external short-circuiting, or electrochemical abuse. During EV’s operation, it is impossible to directly monitor the TRA; however, the change in thermo-electrical characteristics (pattern) during TRA-like events could signal the presence of a failure, allowing for the prediction of LIB malfunction. Thus, in this work, we employ machine learning-based techniques informed by multi-physics models to predict and prevent the TRA in large pouch LIBs as presently used in various EVs.
The multi-physics model is implemented in commercial software Comsol, with the P2D electrochemical model1 and a 3D thermal model. The degradation sub-model2 includes oxygen release in the positive electrode to simulate the overcharge phenomenon during EV’s charging. In addition, the oxygen released in the positive electrode may exothermically react with the electrolyte as well as create significant stress in the electrode, which may lead to the mechanical deformation of the electrode and a subsequent TRA. An LG Chem lithium-ion pouch cell consisting of Li(Ni0.6Mn0.2Co0.2)O2 – NMC622 – cathode and graphite anode are studied to address this severe TRA problem.
As a result of the time-varying nature of the variables that affect TRA, we propose three potential machine learning algorithms. These are Support Vector Machine, Deep Neural Network, and Recurrent Neural Network, tailored and implemented for estimating the TRA likelihood, using thermal images acquired from the multi-physics modeling of LIB pouch cells. Hyperparameters optimization has been performed to identify a set of variables for the best performing ML method. The proposed combined multi-physics and machine learning modeling methodology provide interesting insight and predictive capabilities for TRA prediction.
References

J. Newman and W. Tiedemann, J. Electrochem.
Soc., 140, 1–5 (1993).

X. Feng, X. He, M. Ouyang, L. Wang, L. Lu, D. Ren and S. Santhanagopalan, J. Electrochem. Soc., 165, A3748–A3765 (2018).
(Digital Presentation) Electrochemical Dewatering of Cellulosic Nanomaterials
Authors: Vijapur Santosh Hanamant , Le Huong , Hall Timothy , Taylor E. Jennings , Inman Maria , Snyder Stephen , Nelson Kim 
Published: July 2022

Cellulose is an abundantly available natural resource utilized for cost effective manufacturing of cellulosic nanomaterials that exhibit great potential in a variety of industrial applications. Although cellulosic nanomaterial is cost effective to produce, it is not economical to ship long distance while containing significant water content (>95 wt.%). Therefore, a need has been identified by manufacturers to develop energy-efficient, dewatering or drying of cellulosic nanomaterials.
Accordingly, Faraday Technology in collaboration with GranBio USA, manufacturers of cellulosic nanomaterials, is addressing this need by developing an economical method and system, for electrochemical dewatering of cellulosic nanomaterials including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). Innovative reactor designs are utilized to demonstrate the feasibility of an industrially viable and energy efficient ElectroDewatering approach capable of generating >50 wt.% final solid content for both CNC and CNF. The material properties were maintained through dewatering, and materials with ~25-30 wt.% final solids were successfully rehydrated and redispersed via vortexing. The pulse process approach reduced the energy use by at least 50% compared to thermal drying at similar dewatering performance. We have continued to improve our TRL by scaling the electrochemical dewatering system from sub-scale batch to alpha-scale continuous process. Specifically, this talk will discuss the results of these advancements.

Acknowledgements: The financial support of DOE Contract No. DE-SC0018787 is acknowledged.
(Digital Presentation) Electrochemical Finishing of Mo Feedhorn Arrays
Authors: Hall Timothy , Le Huong , Moran Andrew 
Published: July 2022

Powder bed methods of additive manufacturing (AM) use an electron beam (EBM) to sequentially melt powder, layer by layer, to build up a 3-dimensional object directly from a powder bed according to a computer aided design file. With EBM. there are four steps to build each layer in a build. First, the beam is scanned to preheat the powder bed without melting, second, the contours (outer edge) of the area to be melted is traced and powder melted, third, the hatch (area within the contours) is melted and finally any supports that need to be built to support higher layers of the part being built are added.
The major concerns for incorporation of AM into structural parts are (1) microstructural anisotropy/inhomogeneity, (2) porosity and (3) surface finish that is strongly dependent on the orientation of the surface relative to the build direction. Improving the surface finish is critical for certain applications. While finish machining can be used where surfaces are accessible, one benefit of the complexity of part shape is the possibility of building parts with internal passages, inaccessible to machining.
Therefore, this paper will discuss recent developments toward the demonstration of a process to electrochemically finish the feedhorn arrays produced with Mo by EBM additive manufacturing. Specifically, we will discuss developments toward achieving optimal electrochemical processing conditions, surface finish, nominal tooling, and performance. Unlike conventional surface finishing processes that either use media or machine tools to physically modify the surface, electrochemistry can be used as a non-contact flexible approach, to finish hard to reach surfaces such as the internal channels of refractory materials that maybe inaccessible to conventional processes. This paper will focus on pulse/pulse reverse electrofinishing processes developed by Faraday Technology and the technique to scale this approach to functional parts of interest.

Acknowledgements: The financial support of DOE Contract No. DE-SC0020783 is acknowledged.
Reclaim Mode Post Etch Residue Remover Solutions for Advanced Technology Nodes
Authors: Gupta Rohini , Klipp Andreas 
Published: July 2022

Back-end-of-line (BEOL) processing for creation of vias in advanced technology node semiconductor manufacturing warrants a wet chemistry capable of removing post-etch residue (PERR), titanium nitride hardmask (TiN HM) and etch stop layer (ESL), while being compatible with metals, such as copper, tungsten and cobalt. In accordance with BASF’s core competency of innovating sustainable solutions with minimal environmental impact, our reclaim mode BEOL PERR chemistries allow semiconductor manufacturers to minimize not only their cost of ownership (COO) but also their waste footprint.
BASF’s reclaim mode PERR chemistries, when mixed with appropriate amount of hydrogen peroxide, facilitate oxidative wet etching of TiN HM. In this paper, we demonstrate that optimization of formulation and spiking protocol extends the bath lifetime of these chemistries beyond 24hr, which is significant improvement vis-à-vis current industry standard of single use (drain mode) chemistries. Beaker-level bath lifetime investigation of BASF’s leading formulation confirms that TiN etch rate (ER) and bath pH are stable for 48hr (Fig. 1a) when bath is loaded with commensurate amount of Ti ions. Beaker-level performance was also corroborated by 300mm wafer level assessment. BASF’s reclaim mode PERR chemistries with bath lifetime greater than 8hr offer progressively favorable cost of ownership (COO) vis-à-vis drain mode chemistry (Fig. 1b).

Figure 1
(Invited, Digital Presenter) Semiconductor Technology Challenges, Past, Present and Future
Authors: Sekiguchi Akihisa 
Published: July 2022

Even though a large fraction of the global economy has yet to recover, the semiconductor related industry is doing well in spite the pandemic. The sales of electronic goods worldwide is projected to be $500 Billion (US) annually in 2021. And, according to some estimates, the electronics market may top $1 Trillion (US) in sales by 2030, essentially doubling the market in ten years.
There are a few questions that one may want to ask, like: why is this happening and how did we get here? is this projected growth realistic and sustainable for the next decade? speaking of sustainable, how is the industry addressing the need to be consistent with United Nations SDGs? what are the technical challenges that we are facing going forward? ...the list goes on.
Of course, the author does not have a crystal ball, but will attempt to give a balanced view on factors that may explain how we got here, where we might be headed, and what we need to do collectively. Input and views from a wide range of industry and academic experts and institutions will be presented in this invited presentation.
(Digital Presentation) SiGe Epitaxial Growth on Si Substrate Using Al-Ge Paste
Authors: Suzuki Shota , Matsubara Moeko , Minamiyama Hideaki , Dhamrin Marwan , Uraoka Yukiharu 
Published: July 2022

Silicon-germanium (SiGe) has been considered as an important alternative material to silicon due to its high carrier mobility, low power consumption and excellent performance [1]. However, due to both material unique phase diagram with melting points separated by 376 °C, it is too difficult to realize a good bulk quality of polycrystalline-free SiGe single crystals with controlled Ge contents.
In this work, crystalline thick epitaxial layers of SiGe with Ge contents exceeding 30% are fabricated by screen-printing technology on Si wafers. As illustrated in Figure 1, Aluminum-germanium (AlGe) paste with a mole ratio of 7:3 was prepared and screen-printed on p-type Cz-Si <111> substrate, dried at 100 °C for 10 minutes and then annealed in Ar ambient using IR image furnace at 900 °C for 5 minutes. The Al begins to melt at 660 °C, dissolving the silicon wafer surface and the Ge in the paste. The melted Al, Si and Ge form the liquid phase of the Al-Si-Ge, which when cooling process start, regrown epitaxially at the melt/Si interface to form the Al-doped SiGe crystalline layer.
The formed SiGe was observed by scanning electron microscope (SEM), and energy dispersive X-ray spectrometry (EDX). As can be seen in the cross-sectional SEM image in Figure 2, SiGe layer of about 20mm was formed on the Si substrate surface. It is worth mentioning that the SiGe/Si interface is formed straight as the reaction stopped perfectly on façade <111> forming SiGe layer. EDX mapping of elements suggests that the Al in the Al-Si-Ge liquid phase formed at high temperature is segregated from the liquid to the Al-Ge paste layer during the cooling process and remains only as dopant in the SiGe layer due to its low solid solubility in Si and Ge. The Al-Ge paste residue layer will be etched chemically and further step of chemical mechanical polishing will be performed to improve the surface flatness of SiGe layer to be an epi-ready SiGe/Si substrate for different semiconductor devices applications.
Reference
[1] M. L. Lee and E. A. Fitzgerald, Strained Si/strained Ge dual-channel heterostructures on relaxed Si0.5Ge0.5 for symmetric mobility p-type and n-type metal-oxide-semiconductor field-effect transistors, Appl. Phys. Lett. 83, 4202 (2003).

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(Invited, Digital Presentation) Exploring Interfaces and Polarity to Realize Vertical III-Nitride Superjunction Devices
Authors: Pavlidis Spyridon , Khachariya Dolar , Szymanski Dennis , Reddy Pramod , Kohn Erhard , Sitar Zlatko , Collazo Ramon 
Published: July 2022

In recent years, there has been a surge of research and commercial interest in gallium nitride (GaN)-based devices for power conversion applications. This is largely motivated by the wide bandgap of GaN, which offers a unipolar limit of performance that is larger than that of silicon and silicon carbide. This performance ceiling, however, can be surpassed with the use of superjunction (SJ) structures, a strategy that has now been experimentally proven in both vertical Si- and SiC-based technologies. The ability to selectively dope lateral regions of a semiconductor is a requirement for SJ fabrication, with typical schemes relying on ion implantation, epitaxial regrowth or a combination of both. However, due to the challenges associated with applying conventional selective area doping techniques to GaN, vertical GaN SJ structures have remained elusive.
Recently, our team proposed the use of lateral polar junctions (LPJs) to form vertical GaN SJ devices. This approach exploits the natural doping asymmetry between the N-polar and Ga-polar crystal orientations to simultaneously grow N-polar GaN for the n-type pillars and Ga-polar GaN for the p-type pillars. The first part of this talk will present a design framework for GaN SJ devices. This will reveal several critical design requirements: 1) doping in N-polar GaN must be reduced below 5 × 1017 cm-3 to achieve kV-class devices, 2) charge must be tightly balanced between neighboring pillars in the SJ structure to obtain efficient performance and 3) the barrier height to the N-polar GaN region must be tuned to suppress leakage currents and avoid bipolar operation.
The next part of the talk will focus on the characterization of rectifying contacts to N-polar GaN. While the analysis of Schottky barrier diodes proved the ability to reduce doping to relevant levels, the low barrier height and enhanced chemical sensitivity of N-polar GaN make it challenging to process adequate devices. Thus, low-pressure chemical vapor deposited (LPCVD) silicon nitride (SiN) interlayers were introduced to increase the barrier height. This approach is enabled by surface-termination dependent barrier height and an amphoteric miniband for enhanced conduction via the interlayer. Moreover, the use of the LPCVD SiN interlayer enables operation of the diodes up to 400 °C compared to less than 200 °C for the reference case. In addition, N-polar GaN camel diodes were also designed, fabricated and tested to better tune the barrier height. The latter structure was incorporated into the first charge-balanced GaN superjunction device. A detailed electrical analysis of the GaN LPJ device will represent the final portion of this talk.
The successful demonstration of these experimental building blocks paves the way for the GaN LPJ to be used in future high-voltage GaN SJ devices.
(Invited, Digital Presentation) Fatigue-Resistant of Ag Sinter Joining on Ni-P/Pd/Au Finished DBA Substrate with Thick Ni-P Layer During Thermal Shock Test
Authors: Chen Chuantong , Suganuma Katsuaki 
Published: July 2022

The wide band-gap (WBG) semiconductor, such as silicon carbide (SiC) and gallium nitride (GaN), are widely expected to replace conventional Si-based chips, which provide the power modules with higher working temperature larger than 250 degrees. Ag paste sinter joining emerges as a promising alternative for the die attach material in WBG power devices owing to its superior electrical/thermal conductivity as well as a high melting point of 960℃. For Ag paste sinter joining on WBG chip or substrate, most studies are focusing on Ag metallization layers by which the Ag-Ag interface delivers high bonding strength because of the chemical/structural similarity. However, with the superior anti-oxidation/corrosion property, Au metallization layers ensure the Ag-Au joint much wider usage environment than Ag-Ag joint.
The study was carried out to develop a highly reliable Ag-Au sintering joint in SiC chip and Direct bonded aluminum (DBA) power modules. The DBA substrate was strengthened by an electroless nickel/electroless palladium/immersion gold (ENEPIG) metallization layer. ENEPIG plated DBA substrate was modified to possess superior mechanical strength by thickening the Ni layer with the thickness of 7µm and 20µm. The reliability of SiC/DBA die-attached module by Ag-Au joining was evaluated during a long-term thermal shock test (TST) from -50℃ to 250℃ up to 1000 cycles. In the case DBA with a Ni metallization layer of 7µm, severe plastic deformation occurred at the Ag-Au interface. By thickened ENEPIG layer with Ni-P layer to 20µm, the Ag-Au interfacial deformation derived from Al plastic deformation was successfully suppressed even after 1000 cycles. The shear strength of as-sintered Ag-Au joint was evaluated to be larger than 35 MPa, but degradation was still found to be the interfacial delamination between Ag paste and ENEPIG substrate during thermal shock test for the two ENEPIG metallization cases. The bonding interface and fracture characteristics were systematically investigated, which provide basic understanding between microstructural evolution and reliability of Ag-Au joint during TST.
Mechanism of Reverse Leakage Current in Schottky Diode Fabricated on Large Bandgap Semiconductors like Ga2O3 or Diamond Part II
Authors: Lau Wai Shing 
Published: July 2022

The bandgap of Ga2O3 (4.5-4.9 eV) is larger than the bandgap of GaN (3.4 eV). In addition, single crystal bulk Ga2O3 wafers can be more easily manufactured than GaN wafers. Therefore, Ga2O3 has strong potential for applications in high power semiconductor devices [1]. Schottky diodes fabricated on n-type Ga2O3 have strong potential as fast high-power switching devices. Similarly, the bandgap of diamond (5.5 eV) is very large and diamond Schottky diodes have good potential.
One possible mechanism of reverse leakage current in Schottky diodes is image force barrier lowering at the metal-semiconductor interface. Historically, there were 2 theories regarding the image force barrier lowering effect. In 1953, Krömer published his theory that the image force dielectric constant in the equation for Schottky emission should be equal to 1 [2]. Subsequently in 1964, Sze et al. published their theory that the image force dielectric constant in the equation for Schottky emission should be equal to n2 [3], where n is the refractive index of the semiconductor in the infrared or visible light range. In 1969, Sze published a book which has influenced many scientists [4]. Sze’s theory [3]-[4] quickly became the dominating theory whereas Krömer’s theory essentially became a forgotten theory. In 2020, the author pointed out that Krömer’s theory is quite frequently more compatible with experimental results for Ga2O3 or diamond Schottky diodes [5]. In 2021, the author attempted to propose a new theory involving the concept of electron velocity overshoot to unify Krömer’s theory and Sze’s theory, as shown in Fig. 1 [6]; Krömer’s theory is better than Sze’s theory for high reverse bias voltage.
In conclusion, the author pointed out that it is necessary to resurrect an old and forgotten theory from Krömer in order to explain the experimental data on the reverse leakage current of Schottky diodes fabricated on large bandgap semiconductors like Ga2O3 and diamond, etc. A theoretical basis based on quasi-ballistic transport will be provided.
References
[1] M. Higashiwaki, H. Murakami, Y. Kumagai and A. Kuramata, Jpn. J. Appl. Phys., 55, 1202A1 (2016).
[2] H. Krömer, Zeitschrift fur Physik, 134, 435 (1953). (In German.)
[3] S.M. Sze, C.R. Crowell and D. Kahng, J. Appl. Phys., 35, 2534 (1964).
[4] S.M. Sze, Physics of Semiconductor Devices, p. 367, Wiley Interscience, New York (1969).
[5] W.S. Lau, ECS Trans. 97 (4), 99 (2020).
[6] W.S. Lau, CSTIC 2021 (China Semiconductor Technology International Conference, Shanghai, 2021, IEEE), 1 (2021). (Available from IEEE database.)

Figure 1