bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) High-Performance Ge/Si Electro-Absorption Optical Modulator and Its Highly-Efficient Photodetector Operation
Authors: Fujikata Junichi , Ishikawa Yasuhiko 
Published: December 2024

We studied a high-speed Ge/Si EAM evanescently coupled with a Si waveguide of a p–n junction for a high-bandwidth optical interconnect over a wide range of temperatures from 25 °C to 85 °C.
Figure 1 (a) -(c) show schematic diagrams of a Ge/Si EAM on a Si rib waveguide with a lateral pn junction and cross-sectional TEM image of a Ge/Si EAM. The Ge/Si EAM consists of an evanescently coupled structure with a Si rib waveguide. The stack Ge/Si layer width was changed from 0.3 mm to 1.0 mm, and the Ge height was about 300 nm.
Figure 2 (a) and (b) show output waveforms of 112 Gbps PAM-4 with 2^7-1 PRBS and 100 Gbps NRZ with 2^7-1 PRBS at 1550 nm wavelength, measured at room temperature.
We demonstrated 56 Gbps high-speed operation at high temperatures up to 85 °C. From the photoluminescence spectra, we confirmed that the bandgap energy dependence on temperature is relatively small, which is consistent with that of the operation wavelengths with increasing temperature for a Ge/Si EAM. We also demonstrate a high-speed and high-efficiency Ge photodetector. The photoresponsivity was enhanced by the F-K effect and avalanche-multiplication effect in the C+L band wavelengths. These results demonstrate that the Ge/Si stacked structure is promising for both high-performance optical modulators and photodetectors integrated on Si platforms.

Reference:

J. Fujikata et al., Opt. Express 31(6), 10732 (2023).

J. Fujikata et al., Opt. Express 28(22), 33123 (2020).

Figure 1
Development of Data-Driven Feature Value Map Toward High-Performance Material Exploration
Authors: Yamada Tetsuya , Kitada Riku , Hayashi Fumitaka , Teshima Katsuya 
Published: December 2024

Currently, over 100,000 data on inorganic compounds was reported in the Inorganic Crystal Structure Database (ICSD). Until now, exploration of functional materials has been experimentally carried out using intuition and experience from such huge amount of materials. This approach needs several trials and errors, resulting in consuming times. To overcome this issue, we introduce data-driven exploration system that is guided by crystal structure, composition, and their properties. Since functional performances are strongly dependent of material's properties, this approach should potentially lead to novel discoveries beyond the subjective perception of the researcher. Our research goal is development of a data-driven feature value map that is strongly correlated with a functional performance. To achieve this, we aimed to find contribution factor of material performance in X-ray diffraction (XRD) profiles and structural properties. We also aimed to understand the material exploration efficiency using the feature value map that was composed of these descriptors.
Approximately 100 kinds of crystalline materials were grown and their functional performance was measured. The feature value map was depicted using XRD profiles of over 60,000 reference data and this experimental data. The feature values extracted from XRD profiles (XRD feature values) and structural properties (structural feature values) were used as the explanatory variable to depict the map using t-SNE. The contribution factors for material performance were analyzed by multivariate regression analysis.
The generated feature value map only using XRD feature values exhibits that similar materials in crystal structure make clusters in the map, indicating good explanatory power for crystal structures. However, its regressive prediction accuracy for material performance show low coefficient of determination (COD) at 0.18. By adding some structural feature values, the COD improved up to 0.7. This result clearly indicates the XRD feature values are not major contributing factor and other factors are necessary for high predictive map construction. Under the updated map, we succeeded to find novel material with high functional performance. The detail will be reported in the presentation.
Acknowledgement
This work was partly supported by Priority Project in Aichi Knowledge Hub Aichi, JST Green Technologies of Excellence, the Strategic Innovation Program (SIP) of the Cabinet Office, and joint research with a company.
Optimization of 3D Battery Geometries Using a Combination of Accurate Energy Prediction Models and Automatic Geometry Generator
Authors: Miyamoto Kaito 
Published: December 2024

In order to enlarge the IoT ecosystem, there is a growing need for microbatteries with high areal energy density. A promising approach to improve areal energy density includes using three-dimensional (3D) electrodes, which allow for the holding of more active materials without increasing the internal resistance. Nonetheless, pinpointing the optimal 3D geometry is a challenging task, reliant on the printable materials, the resolution of the production machinery, and the usage of the battery. This constitutes a multiobjective optimization problem, introducing substantial difficulties even when computer simulations are employed because of their high computational cost.
To overcome this challenge, we propose a novel approach for the automated identification of optimal 3D battery geometries, which combines quick and accurate energy prediction models with an automatic geometry generator (AGG). [1-4] The energy prediction models employ simple principal component regression, which results in a significantly reduced computational cost. [2] AGG constructs a 3D geometry by filling the empty cell space with cuboid-shaped electrodes (electrode elements). The placement of each electrode element is determined automatically through the Monte Carlo tree search (MCTS) algorithm, leading to the designation of this method as AGG-MCTS. Given that the dimensions of the electrode elements are determined following the resolution of using fabrication equipment, such as 3D printers, our method ensures the generation of only manufacturable geometries. The combination of the energy prediction models and AGG-MCTS enables the rapid identification of optimal 3D battery geometries, without using human intuition and experience.
In this study, we demonstrate the efficacy of our approach through its application to two standard electrode pairs: LiFePO4/Li4Ti5O12 (LFP/LTO) and LiNi0.5Mn0.3Co0.2O2/graphite (NMC/Graphite). Despite the distinct discharging behaviors of these systems, our regression models accurately predict the discharge-current-dependent energies of both systems.[4] By integrating these models with the AGG-MCTS, we successfully identify frontier solutions and obtain optimal geometries that display 30% - 40% greater energy than the current state of the art. Notably, optimal geometries vary in response to the discharge current and the specific electrode combination. Our approach uniquely facilitates the discovery of material- and discharge-current-dependent optimal geometries for the first time. This advancement underscores the significance of custom-designed batteries for a variety of IoT applications and highlights our method’s potential to enable such designs.
[1] Miyamoto, et al., iScience, 23, 101317 (2020).
[2] Miyamoto, et al., Cell. Rep. Phys. Sci., 2, 100504 (2021).
[3] Miyamoto, et al., J. Power. Sources, 536, 231473 (2022).
[4] Miyamoto, in preparation (2024).
(Invited) Sparking Autonomous Full Cycle Battery Research
Authors: Stein Helge Sören , Zhang Bojing , Rahmanian Fuzhan , Nuss Leah , Yuan Jun , Heaney Dannika , Ke Qiamin , Vogler Monika , Bhowmik Arghya 
Published: December 2024

Materials optimization typically focuses on fine-tuning selected properties of a material for targeted applications. However, optimizing a single material property or component does not necessarily lead to optimized system performance. This talk demonstrates how to design, run, and debug a Materials Acceleration Platform (MAP) that integrates computational and experimental capabilities from dozenz of institutions across Europe to autonomously optimize both material-level properties, like ionic conductivity of electrolytes, and system-level performance, like the end-of-life (EOL) of lithium-ion coin cells, by varying electrolyte formulations.
The MAP leverages automation, robotics, and machine learning to enable high-throughput experimentation, inverse design, and intelligent orchestration of research across the entire battery value chain – from lab benches to manufacturing and back. This holistic, intention-agnostic approach aims to elucidate how materials influence interfaces, components, and full battery packs, and vice versa. By integrating robotic experimentation, intelligent manufacturing, and machine learning models like the Attention-based Recurrent Algorithm for Neural Analysis (ARCANA) of battery lifetime, the MAP seeks to achieve 10-100x acceleration in battery research and development, reducing the current 20-30 year proliferation time to just a few months.
The results demonstrate the MAP's capability to rediscover known trends, like ionic conductivity variation with salt concentration, while also enabling complex multi-scale optimizations spanning materials, components, and full systems. This paradigm shift in research orchestration highlights the power of autonomously linking models, theory, and experiments across domains to spark revolutionary advances in battery technology development.
The talk will conclude with a demo of the Kilofactory, the worlds first fully automated pouch cell factory that starts from active materials precursors and is capable of providing a fully parameterized cell every 15 minutes.
(Invited) Advances in Oxide Thin-Film Transistor Based Inverter Technology
Authors: Nomura Kenji 
Published: December 2024

Several advantages in oxide device processing, including low-temperature processability and exceptional uniformity on a large scale, render oxide device technology essential for a wide range of next-generation electronics. Advancing oxide thin-film transistor-based circuits marks a crucial milestone in developing the next generation of cost-effective ubiquitous electronics. This moves forward oxide-TFT to the forefront of transistor technology, marking the commencement of a new era characterized by low-cost mass-production and high-performance. Extensive efforts have been devoted to developing oxide inverters, including NMOS, and CMOS inverters, and excellent characteristics, such as high-speed separation, low-power dissipation, and sufficient noise marge, have been already demonstrated. Nevertheless, persistent open issues, such as the absence of high-performance p-channel oxide-TFT and the lack of doping control, in oxide semiconductors impede the progress of oxide inverter technology development to the next levels.
This presentation reviews recent advances in oxide-TFT inverter technology and delves into open issues that should be addressed for oxide-TFT-based circuit applications. First, I will present the advancements in oxide-TFT inverter technology, encompassing NMOS, PMOS, and CMOS, primarily drawing from our research activities. Subsequently, we will elucidate and discuss strategies for addressing open issues for the development of high-performance oxide-TFT-based circuit applications.
(Invited) High Performance Metal Oxide Thin Film Transistor Using ALD Technology
Authors: Takahashi Takanori , Uraoka Yukiharu 
Published: December 2024

Field-effect transistors (FETs) based on oxide semiconductors, mainly In2O3 and ZnO, have been commercialized as channel materials for thin-film transistors due to their features such as electron mobility exceeding 10-50 cm2/Vs, extremely low leakage current, and low process temperature. Recently, FETs that can be applied to ferroelectric memory and back end of line have been demonstrated for implementation in ultra-integrated circuits and semiconductor memory. In order to realize various integrated devices using oxide semiconductors, it is necessary to uniformly deposit ultra-thin films of about 5 nm on a three-dimensional structure from the viewpoint of device integration and suppression of short-channel effects. This research group has shown that amorphous In-Ga-O (IGO) is a promising oxide semiconductor material that can be applied to three-dimensional integrated devices. However, it was shown that IGO-FETs have reliability issues because their threshold voltage (Vth) easily fluctuates in response to voltage stress . The purpose of this study was to examine the factors that contribute to Vth instability and to suppress it by evaluating the relationship between FET reliability and IGO composition ratio and annealing temperature, as well as the effect of crystallization.
Top-contact/bottom-gate FETs with AlOx protective films were fabricated by depositing 10-11 nm-thick IGO channels on SiO2 (85 nm)/n++-Si substrates using ALD method Triethylindium and Trimethylgallium The composition ratio of In:Ga in the IGO film was controlled by adjusting the ratio of growth cycles of the InOx and GaOx layers. positive bias stress (PBS), in which a positive voltage is applied to the gate electrode.
The reliability of amorphous IGO against PBS was found to depend on the composition ratio of In:Ga and annealing temperature. It is known that the formation energy of O-O bonds corresponding to excess oxygen is lower in amorphous oxide semiconductors than in single-crystal and polycrystal structures due to their higher structural degrees of freedom. It was experimentally clarified that electron capture occurs more easily in IGO systems than in other oxide semiconductors (Ex. In-Zn-O), which is consistent with theoretical calculations in previous studies. In addition, we focused on crystalline Ga-doped In2O3 to improve the reliability of the IGO system and developed a deposition process using ALD method. We demonstrated that FETs with polycrystalline IGOs as channels have superior mobility and reliability compared to amorphous IGOs. The present study clarified that excess oxygen must be reduced during deposition of oxide semiconductors using the ALD method, and that polycrystalline oxide semiconductors are effective in improving reliability.
(Invited) Mesoscale Ordered Two-Dimensional Semiconductor Polymers with Tunable Dirac Cones and Flat Bands
Authors: Contini Giorghio 
Published: December 2024

Dirac cones, present in the band structure of graphene, are responsible of its remarkable charge-transport properties. However, they are not exclusive to graphene but require that the material presents specific symmetry and delocalized electrons. Efforts have been devoted to identifying 2D materials beyond graphene that offer a greater degree of tunability and a non-zero band gap while retaining high carrier mobility [1].
On-surface synthesis represents an opportunity to manipulate the electronic band structure of the material by varying the molecular building blocks (e.g. by the change of constituent atoms and symmetry). By using a class of heteroatom substituted triangulene monomers we synthesized mesoscale ordered 2D π-conjugated polymers on Au(111) with semiconducting properties arranged in a kagome lattice showing Dirac cone structures and flat bands, theoretically predicted [2-3]. We demonstrate that it is possible to tune the Dirac cone structures and flat bands energy positions by changing the bridging atoms in the triangulene monomers [4]. These results overcome the major barriers to the application of 2D π-conjugated polymers due small domain size and high defect density attained so far.
Although the 2D polymers have been obtained on a metal surface, they can be detached and transferred to other substrates to be used in devices.
References
[1] K. Asano and C. Hotta, Phys. Rev. B 83, 245125 (2011); J.Wang, S. Deng, Z. Liu and Z. Liu, Natl Sci. Rev. 2, 22 (2015).
[2] Y. Jing and T. Heine, J. Am. Chem. Soc. 141, 743 (2019).
[3] G. Galeotti, F. De Marchi, E. Hamzehpoor, O. MacLean, R. M. Rao, Y. Chen, L. V. Besteiro,

Dettmann, L. Ferrari, F. Frezza, P. M. Sheverdyaeva, R. Lui, A. K. Kundu, P. Moras, M. Ebrahimi, M.C. Gallagher, F. Rosei, D.F. Perepichka, G. Contini, Nature Materials, 19, 874 (2020).

[4] D. Dettmann, P. M. Sheverdyaeva, S. Franchi, G. Galeotti, P. Moras, C. Ceccarelli, D.F. Perepichka, F. Rosei, G. Contini, ACS Nano, 18, 849 (2024).
A Comprehensive Study of Ferroelectric Properties of Fluorite-Structured Hf1-XZrxO2 Thin Films Grown on Mo Electrode with Various Thicknesses and Compositions
Authors: Park Ju Yong , Kim Se Hyun , Lee Dong Hyun , Yang Kun , Park Geun Hyeong , Park Min Hyuk 
Published: December 2024

Since ferroelectricity in Si-doped HfO2 was first reported in 2011,[1] HfO2-based thin films have attracted significant attention as an emerging material for ferroelectric devices due to their advantages such as scalability and compatibility with Complementary Metal-Oxide-Semiconductor (CMOS) processes. Generally, TiN has been used as electrode material in semiconductor processes. However, other electrode materials such as W and Mo have attracted increasing interest for HfO2-based ferroelectric thin films due to their higher remanent polarization (Pr) than the TiN electrode.[2
,3
] Recently, it has been reported that Mo electrodes can be easily oxidized even at low temperatures such as atomic layer deposition (ALD) processes, and the formed MoOx layer can sufficiently act as the oxygen supplier, resulting in the larger orthorhombic phase fraction and higher remanent polarization compared with TiN electrodes.[3] Nevertheless, the effect of the film thickness and composition on the ferroelectric properties of HZO thin films grown on Mo electrodes is yet to be elucidated. Therefore, in this study, the electrical, physical, and chemical properties of HZO films with various thicknesses (6 – 11 nm) and Zr/(Hf+Zr) ratios (0.5 – 0.7) are examined.
In the case of the HZO films grown on the TiN electrode, when the film thickness decreases or the Zr/(Hf+Zr) ratio increases, the switchable polarization (2Pr) decreases with a distortion of polarization-electric field (P-E) curves owing to the increased fraction of the antiferroelectric tetragonal phase. However, 2Pr as high as 57.5 µC/cm2 on the Mo electrode could be achieved even in the 7.6 nm-thick Hf0.4Zr0.
6O2 thin film with a little distortion of the P-E curve. The highest 2Pr of 68.3 µC/cm2 was observed in the 10.9 nm thick Hf0.4Zr0.
6O2 film, which is 31.3 % higher than the highest 2Pr (52.0 µC/cm2) of the HZO thin film on TiN reported so far.[
4] Additionally, in the (Grazing Incidence X-ray Diffraction) results of all samples, it can be observed that the m-phase which deteriorates the Pr values is sufficiently suppressed. These results are consistent with the tendency of previously reported results.[3] Therefore, It is believed that the Mo electrode would induce a higher orthorhombic phase fraction in HZO thin films compared to the TiN electrode resulting in higher 2Pr values. This enables ferroelectricity to be achievable within a wider range of film thicknesses and Zr/(Hf+Zr) ratios.

References

[1] Boescke et al., Appl. Phys. Lett., 99, 102903 (2011)
[2] K. Yang et al., Mater. Sci. Semicond. Process., 164, 107565 (2023)
[3] Y. Lee et al., Appl. Surf. Sci., 648, 158948 (2024)
[4] S. J. Kim et al., Appl. Phys. Lett., 111, 242901 (2017)

Figure 1
Ionic Transport Mechanism of All-Solid-State Lithium Batteries with Barium Titanate Nanofillers
Authors: Lai Chi-Yen , Huang Yu-Yao , Yeh Che-Ning 
Published: December 2024

Liquid electrolytes are widely used in rechargeable batteries but face challenges such as flammability, leakage, and limited ability to suppress dendrite formation. In contrast, solid-state electrolytes offer higher safety and better dendrite suppression capability, mitigating risks associated with liquid electrolytes. The materials that are commonly used for solid-state electrolytes include ceramics and polymers. Although ceramic electrolytes exhibit higher ionic conductivity with excellent dendrite suppression ability, their interfacial contact with electrodes is poor. In contrast, polymer electrolytes exhibit excellent interfacial contact with electrodes but suffer from lower ionic conductivity. Therefore, combining polymers as the matrix and ceramics as the fillers to form composite polymer electrolytes (CPEs) shows promise in enhancing their electrochemical properties.
Ferroelectric materials, known for their ferroelectricity and high dielectric constant, have shown their potential as fillers to enhance ion transport and lithium salt dissolution in solid-state electrolytes. In this work, we choose BaTiO3 (BTO) as the filler due to its high dielectric constant and induced electric field under an applied electric field. The dielectric constant and ionic conductivity of CPEs is affected by the amount of added fillers, with an optimal content for conductivity and cycling performance. To date, few studies have explored the relationship and mechanism between the dielectric constant of ferroelectric material fillers and their electrochemical properties. We aim to investigate this relationship by adjusting grain size, morphology, and doping content of fillers to modify their dielectric constants, thereby deepening our understanding of this material system.
Surface Engineering of Cobalt Nano Cube by Enhanced Nitrogen Content in Surface Carbon Shell for Efficient Hydrogen Evolution Reaction in Anion Exchange Membrane Water Electrolysis
Authors: Kang Byeong Guk , Lee Ru Li , Kim Tae Hong , Kang Bong Kyun 
Published: December 2024

To address the pressing concerns of fossil fuel depletion and environmental degradation, extensive research is underway on hydrogen production via water electrolysis. The formidable energy barrier inherent in electrochemical water decomposition significantly impedes efficient hydrogen generation, thus necessitating the development of highly effective electrocatalysts.
Surface modifications of transition metals offer a promising avenue for reducing the energy barrier associated with the hydrogen evolution reaction (HER), as well as the hybrid structure with carbon materials can augment electrical conductivity and structural resilience. Furthermore, surface engineering through nitrogen doping on carbon shells can furnish electrochemically active catalytic sites.
In this study, we present the synthesis of Cobalt-Iron nano cubes encapsulated within a nitrogen-doped carbon shell. The N-doped carbon shell was obtained through the calcination of a polymer layer coated on a Co-Fe Prussian blue analogue precursor. Additionally, the nano cubes were further encapsulated in a melamine layer to enhance the nitrogen dopant content, thus optimizing the electrocatalytic performance.
The optimized CoFe@highly n-doped shell exhibits a low overpotential (98.2 mV) than CoFe@n-doped shell (133.2 mV) at 10 mA cm-2 on alkaline HER performance, and the exhibited performances were stable after 3,000 CV cycles. To commercialize electrocatalyst for hydrogen production, the CoFe@highly n-doped shell was applicated on anion exchange membrane (AEM) device. The CoFe@highly n-doped shell as cathode catalyst in AEM water electrolyzer shows low cell voltage of 1.808 V to achieve current density of 0.5 A cm-2.