Article
Engineering, Electrical & Electronic
Md Toriqul Islam, Mool C. Gupta
Summary: This paper presents a new method for depositing polycrystalline GeSn thin films on a silicon substrate, using simultaneous laser sintering of nanoparticles and recrystallization. The films showed high hole mobility and efficient absorption of near-IR to mid-IR light, making them suitable for mid-infrared photodetector applications.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2023)
Article
Chemistry, Physical
Vadim Kovalyuk, Evgeniia Sheveleva, Mark Auslender, Gregory Goltsman, Roni Shneck, Zinovi Dashevsky
Summary: Polycrystalline PbTe:In films were prepared and studied for their structural and transport properties. Heat treatment in an argon atmosphere resulted in an increase in Hall mobility and electron mean free path. The ultimate goal of this study is to develop portable uncooled photodetectors for the mid-IR range.
Article
Multidisciplinary Sciences
Toshifumi Imajo, Takashi Suemasu, Kaoru Toko
Summary: This study investigates the strain effects on the crystal and electrical properties of polycrystalline Ge layers, finding that large strains promote large crystal grains and the direction of strain significantly affects the potential barrier height of the grain boundary. These findings will be valuable for designing Ge-based thin-film devices for Internet-of-Things technologies on various materials.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Physical
Takuto Mizoguchi, Toshifumi Imajo, Jun Chen, Takashi Sekiguchi, Takashi Suemasu, Kaoru Toko
Summary: Group-IV alloy semiconductors, particularly Ge thin films, with enhanced crystallinity and carrier mobility have been studied using a multistep heating process. The investigation of crystal and electrical properties in Si1-xGex and Ge1-ySny alloys showed that controlling the temperature in each stage can improve carrier mobility by increasing grain size. Moreover, Sb doping contributes to enlarging grain size and controlling the conduction, while electron concentration varies with composition.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Nanoscience & Nanotechnology
S. Zhao, Y. Zhao, C. Deng, L. Pan
Summary: Carrier mobility and concentration of polycrystalline-amorphous carbon nanocoils (CNCs) were probed for the first time, revealing a significant decrease in carrier concentration with temperature increase. X-ray diffraction characterization attributed this phenomenon to thermal expansion and compression of grains. Additionally, the characteristics of individual CNCs showed variations in carrier mobility and concentration during the growth process.
MATERIALS TODAY NANO
(2022)
Article
Chemistry, Physical
Moushumi Dutta Purkayastha, Tapas Pal Majumder, Mitali Sarkar, Sharmistha Ghosh
Summary: This study reports the successful synthesis of a titanium oxide-silicon dioxide nanocomposite with good UV screening properties and reduced photoactivity. The nanocomposite exhibited a unique rod-like morphology with a reduced surface area, which likely trapped the photoactive TiO2 particles within the SiO2 rods. Additionally, the nanocomposite showed a tunable band gap, making it suitable for optoelectronic applications.
RADIATION PHYSICS AND CHEMISTRY
(2022)
Article
Engineering, Electrical & Electronic
Kenta Moto, Keisuke Yamamoto, Toshifumi Imajo, Takashi Suemasu, Hiroshi Nakashima, Kaoru Toko
Summary: Thin-film transistor (TFT) applications of GeSn have attracted attention due to their ability to improve electronic device performance, with the appropriate amount of Sn effectively passivating defects in Ge and reducing the density of defect-induced acceptors and grain boundary traps to achieve a high Hall hole mobility (>200 cm(2) V-1 s(-1)). The performance of accumulation-mode TFTs fabricated under 400 degrees C strongly depended on the initial Sn concentration x(i), achieving both a high field-effect mobility (170 cm(2) V-1 s(-1)) and on/off ratio (10(3)) at x(i) = 1.6%. This performance was shown to be the highest among Ge-based TFTs with grain boundaries in the channel.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Physics, Applied
Petro Lytvyn, Andrian Kuchuk, Serhiy Kondratenko, Hryhorii Stanchu, Sergii V. Malyuta, Shui-Qing Yu, Yuriy I. Mazur, Gregory J. Salamo
Summary: Elastic strain engineering in the GeSn bandgap structure is an attractive area for designing novel material properties. The linear interpolation of the elastic constants of Ge and Sn is commonly used to estimate their respective values for Ge1-xSnx alloys. This work reveals that the Young's modulus of Ge1-xSnx epitaxial layers has a non-monotonic dependence on Sn composition. An anomalous increase in the elastic modulus is observed with the further increase in Sn content (12 at. %), which is also accompanied by an increase in in-plane tensile strain. The observed anomalous behavior of the Young's modulus for these GeSn epitaxial layers appears to be related to their recently predicted and observed short-range atomic order.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Ceramics
Aude Cumont, Ruoying Zhang, Yuting Zheng, Louise Corscadden, Marco R. Oggioni, Chengming Li, Ran Liu, Haitao Ye
Summary: The electronic and mechanical properties, as well as the biocompatibility, make diamond-based materials a promising option for biomedical applications. The cost of producing high-quality single crystal diamond films remains a challenge, but the emergence of polycrystalline diamond films grown by chemical vapor deposition offers a more affordable alternative. The PCD films grown on silicon wafers have been characterized for their nearly pure carbon content, small tensile stress, and antibacterial properties against both Gram-negative and Gram-positive bacteria.
CERAMICS INTERNATIONAL
(2021)
Article
Chemistry, Multidisciplinary
Christopher Perez, Atharv Jog, Heungdong Kwon, Daniel Gall, Mehdi Asheghi, Suhas Kumar, Woosung Park, Kenneth E. Goodson
Summary: In this study, time-domain thermoreflectance was used to uncover cross-plane heat conduction mechanisms in high aspect ratio metal nanostructures. The findings demonstrate the existence of unexplored heat transport modes in nanostructured metals, which can be utilized to develop electro-thermal solutions for modern microelectronic devices and sensors.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Materials Science, Ceramics
Guan-Yi Hung, Pin-Yi Chen, Chi-Yun Wang, Chi-Shun Tu, Cheng-Sao Chen, Po-Liang Lai, Kuei-Chih Feng
Summary: This study improved the mechanical properties of bioactive CaO-SiO2-P2O5 glass-ceramics by adding the nucleating agent P2O5, and demonstrated its excellent biological behavior through in vitro and in vivo experiments. The glass-ceramic exhibited high flexural strength and hardness, and released Ca2+ ions to promote cell viability and bone formation. This work provides a promising route for utilizing P2O5-nucleated CaO-SiO2-P2O5 glass-ceramics for load-bearing bone replacement.
CERAMICS INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
Snehal Mandal, I Das
Summary: The magnetotransport properties of polycrystalline La0.7Sr0.3MnO3 (LSMO) ultrathin films can be tuned by varying film thickness and grain size. A two-step deposition method was introduced to prevent reaction of the films with SiO2 at high temperatures. The dominance of intergranular spin polarized transport (SPT) phenomena in these ultrathin films was evidenced from low field magnetoresistance at low temperatures, making them suitable for spintronic device applications.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Yu-Zhou Zhang, Shi-Rong Zhang, Dun-Bo Yu, Yang Luo, Ning-Tao Quan, Wen-Long Yan, Kuo-She Li
Summary: Through experiments conducted under different Ar gas pressures and substrate temperatures, it was found that low Ar gas pressure and sufficient deposition time contribute to the formation of Gd hcp phase with better magnetic properties. High substrate temperature helps reduce the internal stress in Gd films and promotes lattice parameters closer to those of the ideal Gd hcp structure.
Article
Nanoscience & Nanotechnology
Sung-In Mo, Sungjin Choi, Jeong-Ho An, Bo-Jong Kim, Kwan Hong Min, Sungeun Park, Ji-Eun Hong, Soong Ju Oh, Hee-eun Song, Joon-Ho Oh, Ka-Hyun Kim
Summary: This study investigates the microstructural evolution, dopant in-diffusion, and carrier transport mechanism in the electron and hole contacts of poly-Si/SiOx solar cells. The results demonstrate that the passivation properties and carrier transport mechanisms are strongly influenced by the microstructural evolution and dopant in-diffusion. Electron and hole contacts exhibit common behaviors regarding microstructural evolution and dopant in-diffusion, but hole contacts show relatively inferior electrical properties overall.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Multidisciplinary
Jing Xie, Yangfang Liao, Dongni Wu, Quan Xie
Summary: This study aims to investigate the atomic ordering dependence of magnetic and magneto-transport properties in polycrystalline Fe3Si films on Si(111) substrates by inserting a MgO buffer layer. Results show that as the structural and chemical order improves, the M-s value increases and the H-c value decreases, with the highly ordered D0(3)-Fe3Si film exhibiting the highest M-s value and the lowest H-c value. The resistivity of Fe3Si films decreases with the improvement of atomic ordering, influenced by different scattering mechanisms at various temperature ranges. Analysis of the anomalous Hall effect demonstrates that intrinsic contributions are enhanced by the improvement of structural and chemical order, while extrinsic contributions behave oppositely.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Sora-at Tanusilp, Masaya Kumagai, Yuji Ohishi, Naoki Sadayori, Ken Kurosaki
Summary: The study shows that Sn(SbTe2)(2) has a large anharmonicity, leading to its low thermal conductivity, making it an excellent thermoelectric material with relatively high thermoelectric figure of merit.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Sora-at Tanusilp, Masaya Kumagai, Yuji Ohishi, Hideki Furusawa, Motoomi Suwabe, Ken Kurosaki
Summary: In this study, a highly dense bulk sample of ZrW2O8 was synthesized using spark plasma sintering technique, and its thermal conductivity, mechanical properties, and other physical properties were investigated. It was found that ZrW2O8 exhibited unique thermal properties and could be potentially used in thermal management areas.
ADVANCED ENGINEERING MATERIALS
(2022)
Article
Multidisciplinary Sciences
Andrea Ronchi, Paolo Franceschini, Andrea De Poli, Pia Homm, Ann Fitzpatrick, Francesco Maccherozzi, Gabriele Ferrini, Francesco Banfi, Sarnjeet S. Dhesi, Mariela Menghini, Michele Fabrizio, Jean-Pierre Locquet, Claudio Giannetti
Summary: Mott metal-insulator transition in real materials is characterized by complex lattice and electron dynamics involving multiple length and time scales. The authors use a combination of experimental probe and modelling to investigate the nanoscale dynamics across the Mott transition in V2O3. The study reveals the formation of spatially inhomogeneous regions during the transition, which host transient non-thermal electronic and lattice states triggered by light excitation. The findings also demonstrate the photo-induced stabilization of the monoclinic metal phase, which only emerges as a metastable state when light excitation is combined with the underlying nanotexture of the monoclinic lattice.
NATURE COMMUNICATIONS
(2022)
Article
Nuclear Science & Technology
Yifan Sun, Shiho Watanabe, Hiroaki Muta, Yuji Ohishi, Ken Kurosaki
Summary: Re-criticality analysis is crucial for safe retrieval and storage of the fuel debris at the Fukushima Dai-ichi Nuclear Power Plant. This study investigates the oxidation behavior and phase formation of Pu-doped and Gd-doped (U,Zr)O-2 solid solutions. Surrogate materials (CeO2) were used to mimic the behavior of PuO2. Analysis reveals the distribution and transformation of phases after oxidation.
JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Applied
Tatsuro Maeda, Kazuaki Oishi, Hiroto Ishii, Hiroyuki Ishii, Wen Hsin Chang, Tetsuji Shimizu, Akira Endoh, Hiroki Fujishiro, Takashi Koida
Summary: In this study, the fabrication and investigation of Schottky barrier contact on n- and p-type In0.53Ga0.47As with transparent conductive oxide (TCO) that transmits light is presented. The contact shows explicit rectifying behavior and insertion of an ultra-thin Ni-layer reduces contact resistivity significantly. This contact has potential for broadband light detection in the optical communication band.
APPLIED PHYSICS LETTERS
(2022)
Article
Nanoscience & Nanotechnology
Yifan Sun, Jiahui Fu, Yuji Ohishi, Keita Toh, Koichiro Suekuni, Kunihiro Kihou, Ushin Anazawa, Chul-Ho Lee, Ken Kurosaki
Summary: Thermoelectric (TE) modules require mechanically robust n-and p-type legs to ensure structural integrity during operation. Mg3Sb2 and MgAgSb have shown promise as components for low-temperature TE modules. However, the difference in their coefficients of thermal expansion (CTEs) and oxidation resistances at increased temperatures raise concerns. This study addresses these issues by alloying Mg3Sb2 with Mg3Bi2, reducing its CTE and confirming stability in air and Ar at temperatures below 570 K. The results suggest the compatibility and robustness of Mg3Sb1.5Bi0.5 and MgAgSb as thermoelectric legs for low-temperature TE modules.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Takafumi Ishibe, Yuki Komatsubara, Kodai Ishikawa, Sho Takigawa, Nobuyasu Naruse, Yutaka Mera, Yuichiro Yamashita, Yuji Ohishi, Yoshiaki Nakamura
Summary: This study demonstrates the simultaneous achievement of ultralow thermal conductivity and high thermoelectric power factor in epitaxial GeTe thin films/Si substrates through a combination of interface engineering and point defect control. The formation of Te-poor GeTe thin films with low-angle grain boundaries and twin interfaces contributes to the ultralow lattice thermal conductivity of similar to 0.7 +/- 0.2 Wm(-1) K-1, which is comparable to the theoretical minimum value. Additionally, the GeTe thin films exhibit a high thermoelectric power factor due to the suppression of Ge vacancy generation and minimal grain boundary carrier scattering. The combination of domain engineering and point defect control presents a promising approach for developing high-performance thermoelectric films.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Filippo Franceschini, Maria Recaman Payo, Koen Schouteden, Jon Ustarroz, Jean Pierre Locquet, Irene Taurino
Summary: Reliable and microchip-compatible approaches to catalyst development for non-enzymatic glucose sensing using thin films of VOx on glassy carbon electrodes are reported. The electrochemical behavior of the VOx films and partial etching during polarization are examined, and a mechanistic description of the electrochemical process is proposed. The sensors show a wide linear range, good sensitivity, and a low limit of detection, making them promising for energy-efficient integrated electrochemical sensors and non-enzymatic glucose sensing.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Sora-at Tanusilp, Masaya Kumagai, Yuji Ohishi, Manabu Ishimaru, Naoki Sadayori, Ken Kurosaki
Summary: By introducing planar structural defects, SiB6 material exhibits low thermal conductivity but unusually high strength. Polycrystalline SiB6 with planar defects (PD-SiB6) has a relatively high Vickers hardness, comparable to well-known superhard materials, despite its low thermal conductivity. Transmission electron microscopy observations confirmed the presence of numerous planar defects, which are believed to contribute to hardness improvement. Due to the trade-off relationship between thermal conductivity and strength, PD-SiB6 can be utilized for controlling thermal and mechanical properties in various functional materials.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Nuclear Science & Technology
Yifan Sun, Yuji Ohishi, Junya Higaki, Hiroaki Muta, Ken Kurosaki
Summary: Following the Fukushima Daiichi nuclear power plant accident, the development of accident tolerant fuels (ATFs) has become important in promoting nuclear safety. This study investigates the properties of non-radioactive LaB6 and CeB6 to estimate the potential properties of UB6, a promising ATF with little known information. The comparison with UO2, UB2, and UB4 helps determine whether the fabrication of UB6 under high pressure or with other dopants is worthwhile for ATF development.
JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
(2023)
Article
Astronomy & Astrophysics
A. Sider, C. Di Fronzo, L. Amez-Droz, A. Amorosi, F. Badaracco, P. Baer, A. Bertolini, G. Bruno, P. Cebeci, C. Collette, J. Ebert, B. Erben, R. Esteves, E. Ferreira, A. Gatti, M. Giesberts, T. Hebbeker, J. van Heijningen, J-S Hennig, M. Hennig, S. Hild, M. Hoefer, H-D Hoffmann, L. Jacques, R. Jamshidi, R. Joppe, T-J Kuhlbusch, M. H. Lakkis, C. Lenaerts, J-P Locquet, J. Loicq, B. Long Le Van, P. Loosen, M. Nesladek, M. Reiter, A. Stahl, J. Steinlechner, S. Steinlechner, F. Tavernier, M. Teloi, J. Vilaboa Perez, M. Zeoli
Summary: To achieve the expected sensitivity level of third-generation gravitational-wave observatories, more accurate and sensitive instruments are needed to reduce all sources of noise, especially seismic noise. This article presents the activities of the E-TEST to develop and test new key technologies for the next generation of GW observatories, including a compact isolator system, cryogenic silicon mirrors, and improved optical wavelength readouts.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Materials Science, Multidisciplinary
Wei-Fan Hsu, Simon Mellaerts, Claudio Bellani, Pia Homm, Noriyuki Uchida, Mariela Menghini, Michel Houssa, Jin Won Seo, Jean-Pierre Locquet
Summary: Transition metal oxides exhibit rich phase diagrams due to the strong interplay of multiple degrees of freedom. The Mott material V2O3 undergoes a metal-insulator transition at both room and low temperatures, driven by electronic, structural, and magnetic ordering. Using first-principle calculations and Raman spectroscopy, the phonon dynamics of V2O3 were investigated to understand the interplay of these ordering mechanisms. The results revealed that the Raman active vibrations correspond to the structural distortions observed in the phase diagram. Additionally, Raman spectroscopy on epitaxial strained Cr-doped V2O3 thin films identified the importance of local V-V dimer elongation in driving the metal-insulator transition.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Thermodynamics
Toshiki Kondo, Taro Toda, Junichi Takeuchi, Shin Kikuchi, Florian Kargl, Hiroaki Muta, Yuji Ohishi
Summary: To establish an evaluation method for nuclear reactor safety under severe accidental conditions, it is necessary to obtain the physical properties of molten materials. The reaction between stainless-steel oxide and structural concrete is important for understanding severe accidents in nuclear power plants. The thermophysical properties of a (Fe2O3)0.95-(SiO2)0.05 mixture were obtained to study its potential use as a sacrificial material in core catchers.
HIGH TEMPERATURES-HIGH PRESSURES
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Michiel Gidts, Wei-Fan Hsu, Maria Recaman Payo, Shashwat Kushwaha, Chen Wang, Frederik Ceyssens, Dominiek Reynaerts, Jean-Pierre Locquet, Michael Kraft
Summary: This paper presents the fabrication and characterization of a piezoresistive pressure sensor based on Cr-doped V2O3 thin film. It demonstrates, for the first time, the piezoresistive effect of single crystalline Cr-V2O3 thin film and its implementation as a pressure sensor. The piezoresistors on the membrane experience a stress change caused by the pressure input, leading to a phase transition of the material and resulting in a resistivity change. This new piezoresistive mechanism opens up possibilities for highly sensitive sensors based on phase transition.
2023 IEEE 36TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, MEMS
(2023)
Article
Materials Science, Multidisciplinary
Paolo Franceschini, Veronica R. Policht, Alessandra Milloch, Andrea Ronchi, Selene Mor, Simon Mellaerts, Wei -Fan Hsu, Stefania Pagliara, Gabriele Ferrini, Francesco Banfi, Michele Fabrizio, Mariela Menghini, Jean-Pierre Locquet, Stefano Dal Conte, Giulio Cerullo, Claudio Giannetti
Summary: In this study, we demonstrate coherent optical control of orbital occupation in V2O3, which determines the insulator-to-metal transition. Comparing experimental results with numerical solutions, we find that the electronic coherence time is approximately 5 fs. Temperature-dependent experiments also reveal an enhanced electronic coherence time near the critical temperature of the transition, emphasizing the role of fluctuations in determining electronic coherence. These findings provide new possibilities for selectively switching quantum materials' functionalities and coherently controlling solid-solid electronic transformations.
