Article
Materials Science, Multidisciplinary
Deyuan Li, Hui Li, Bingsheng Li
Summary: Stacking faults play a crucial role in enhancing the radiation resistance of SiC. We have introduced a novel method to create stacking faults through the recrystallization of amorphous SiC formed by Si implantation at room temperature. The density and length of stacking faults were examined using transmission electron microscopy. The recombination of defects was found to be dependent on the orientation of stacking faults, with reduced defect density observed when the habit plane of the stacking faults was perpendicular to the irradiation surface.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Chemistry, Multidisciplinary
Eugenia Peresypkina, Berthold Stoeger, Alexander Virovets
Summary: A solid-to-solid transformation accompanied by a unit cell change and the vanishing of crystallographic disorder was observed for a Ta-based peanut-shaped supramolecule crystal under X-rays.
Article
Nanoscience & Nanotechnology
Fuzhou Han, Geping Li, Fusen Yuan, Yingdong Zhang, Wenbin Guo, Muhammad Ali, Jie Ren, Chengze Liu, Hengfei Gu
Summary: The presence of stacking faults (SFs) in Zr3Ge secondary phase particles (SPPs) in Ge-modified Zirconium alloys significantly affects their stability, and the formation of SFs is induced by mechanical stress exerted by the adjacent Face-centered cubic Zirconium (FCC-Zr) phase.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
H. S. Sen, N. Daghbouj, B. S. Li, A. T. AlMotasem, F. F. Ge, L. Zhang, M. Callisti, T. Polcar
Summary: The study examined the microstructure evolution of 6H-SiC under sequential iron and helium ion irradiation, followed by annealing. Amorphization occurred after irradiation, but epitaxial recrystallization and the formation of defected polycrystalline 6H-SiC were observed during annealing. The interaction between stacking faults and microstructural defects was investigated, highlighting the complex interplay between mechanical and electronic factors.
Article
Materials Science, Ceramics
Zhiming Li, Limin Zhang, Weilin Jiang, Chenglong Pan, Xuan Meng, Liang Chen
Summary: This study investigates the hardness of nanocrystalline silicon carbide with different grain sizes and compares it with amorphous and single-crystal SiC. It also explores the effects of irradiation on the hardness of different SiC structures. The results show that irradiation can increase or decrease the hardness of SiC, depending on the temperature and structure. The study highlights the importance of understanding the behavior of SiC under different conditions.
CERAMICS INTERNATIONAL
(2022)
Article
Chemistry, Physical
Amalia Navarro, Elisa Garcia-Tabares, Quentin M. Ramasse, Pablo Cano, Ignacio Rey-Stolle, Beatriz Galiana
Summary: Integration of GaP layers on silicon substrates using AsH3 pre-exposure followed by a PH3-based GaP epitaxial growth allows the development of very promising processes for the photovoltaic industry. However, many of the growth routines using this approach suffer from reproducibility issues, leading to poor quality layers. This lack of knowledge on the mechanisms behind the formation of common planar defects and their dynamics hinders the successful transfer of the method to new epitaxial systems.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Xiyue Cheng, Yueping Zhang, Lijuan Liu, Xiaoyang Wang, Myung-Hwan Whangbo, Jing Lin, Shuiquan Deng
Summary: By utilizing first-principles calculations and high-throughput crystal structure prediction methods, three energetically favorable structures for SBBO were identified, with the Pm-S structure being the best. Despite this, the Cm structure, with higher symmetry, was also found to be almost equally good in certain aspects. Through atom response theory analysis, the importance of local inversion symmetry in reducing the second-harmonic generation (SHG) response of SBBO was elucidated at the atomic and orbital level.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Multidisciplinary Sciences
Christian Dam Vedel, Soren Smidstrup, Vihar P. Georgiev
Summary: In this study, polytypic defects in Indium Phosphide (InP) were investigated using density functional theory and non-equilibrium Greens functions. The study found that interfaces between the Zincblende crystal structure and the Wurtzite phase in InP exhibit anisotropic band structure transition and require a minimal width of 10 nm for crystal-phase quantum wells. Despite reducing conductivity across the defect-plane, a high degree of polytypic defects is still desirable due to a higher fraction of Wurtzite segments in a highly phase-intermixed system.
SCIENTIFIC REPORTS
(2022)
Article
Nanoscience & Nanotechnology
Yongzhao Yao, Keiichi Hirano, Yoshihiro Sugawara, Kohei Sasaki, Akito Kuramata, Yukari Ishikawa
Summary: In this study, Borrmann effect x-ray topography was used to observe dislocations and other structural defects in a thick beta-Ga2O3 (001) substrate. The method allowed for the imaging of defects throughout the entire substrate thickness by producing a strong diffraction beam using the Borrmann effect in a symmetrical Laue geometry. The results demonstrated that Borrmann effect x-ray topography is a powerful technique for studying defects in highly absorbing beta-Ga2O3.
Article
Multidisciplinary Sciences
Da Wang, Ernest B. van der Wee, Daniele Zanaga, Thomas Altantzis, Yaoting Wu, Tonnishtha Dasgupta, Marjolein Dijkstra, Christopher B. Murray, Sara Bals, Alfons van Blaaderen
Summary: This study demonstrates 3D real-space structural analysis of binary nanoparticle crystals using electron tomography, revealing defect analysis at the single-particle level. It shows that an excess of one species in the binary mixture suppresses the formation of icosahedral order, allowing the study of binary crystal structures with a spherical morphology. The methodology can be applied to study a broad range of binary crystals and provide insights into structure formation mechanisms and structure-property relations of nanomaterials.
NATURE COMMUNICATIONS
(2021)
Article
Engineering, Mechanical
Zhiwei Zhang, Qiang Fu, Jun Wang, Rong Yang, Pan Xiao, Fujiu Ke, Chunsheng Lu
Summary: Introducing superlattice intrinsic stacking faults can enhance the strength and toughness of materials through nanostructural design. The enhancing effect of superlattice intrinsic stacking faults is more significant compared to twin boundaries. Experimental results show that the yield strength of samples with superlattice intrinsic stacking faults is always superior to their single crystalline counterparts.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Chemistry, Physical
Andreas Leitherer, Byung Chul Yeo, Christian H. Liebscher, Luca M. Ghiringhelli
Summary: AI-STEM is an artificial intelligence-based method that automatically identifies crystal structures and interface characteristics from atomic resolution scanning transmission electron microscopy (STEM) images. It achieves accurate identification of crystal structure, lattice orientation, and interface location in synthetic and experimental images without explicit information on structural patterns at the interfaces.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Michael A. Sinnwell, Ryan H. Groeneman, Benjamin J. Ingenthron, Changan Li, Leonard R. MacGillivray
Summary: Rare and challenging, the preparation of cyclobutanes with four different substituents has been achieved through a cocrystallisation strategy enabling [2+2] cross-photoreaction of non-symmetrical stilbene derivatives to yield chiral tetrasubstituted cyclobutanes with up to four different substituents in quantitative yield.
COMMUNICATIONS CHEMISTRY
(2021)
Article
Physics, Applied
J. Nishio, C. Ota, R. Iijima
Summary: During epitaxial growth of SiC, it is possible for Shockley partial dislocation pairs to convert from unexpandable to expandable combinations. Research has shown that certain unexpandable dislocations in the substrate can transform into expandable dislocations after growth, potentially impacting the reliability of SiC power devices.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Condensed Matter
Abdesamed Benbedra, Hamza Abbassa, Abdelkader Boukortt, Roland Hayn, Said Meskine, El Habib Abbes
Summary: This article investigates the spontaneous polarization of nanomaterials, using the trigonal structure as a reference state and comparing it with the previous results using the zinc blende structure. The theoretical value of spontaneous polarization is obtained by calculating the basal stacking faults with periodic hexagonal supercells, and it is found to be very close to the experimental measurement.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Materials Science, Multidisciplinary
Jianbo Liang, Yuji Nakamura, Tianzhuo Zhan, Yutaka Ohno, Yasuo Shimizu, Kazu Katayama, Takanobu Watanabe, Hideto Yoshida, Yasuyoshi Nagai, Hongxing Wang, Makoto Kasu, Naoteru Shigekawa
Summary: Direct integration of GaAs and diamond was achieved at room temperature via surface activated bonding, forming an ultrathin crystal defect layer. GaAs TLM patterns on diamond substrates demonstrated excellent heat dissipation properties due to the high thermal conductivity of diamond.
DIAMOND AND RELATED MATERIALS
(2021)
Article
Physics, Applied
Yutaka Ohno, Jie Ren, Shingo Tanaka, Masanori Kohyama, Koji Inoue, Yasuo Shimizu, Yasuyoshi Nagai, Hideto Yoshida
Summary: Through the use of atom probe tomography combined with a focused ion beam operated at -150 degrees C, the three-dimensional distribution of oxygen atoms segregated at sigma 9{114} grain boundaries in Czochralski-grown silicon ingots was analyzed with high spatial resolution. The analysis revealed a narrow segregation range of oxygen atoms across the grain boundary plane, with segregation sites existing at bond-centered sites under tensile stresses above 2 GPa, as calculated by ab initio local stress calculations.
APPLIED PHYSICS EXPRESS
(2021)
Article
Chemistry, Multidisciplinary
Jianbo Liang, Ayaka Kobayashi, Yasuo Shimizu, Yutaka Ohno, Seong-Woo Kim, Koji Koyama, Makoto Kasu, Yasuyoshi Nagai, Naoteru Shigekawa
Summary: The direct integration of GaN and diamond for high-power devices faces challenges due to mismatch in lattice and thermal-expansion coefficients. A successful fabrication of GaN/diamond heterointerface was achieved using a surface activated bonding method at room temperature. An intermediate layer composed of amorphous carbon and diamond is formed at the interface, with Ga and N atoms diffusing during the bonding process and transitioning to diamond after annealing.
ADVANCED MATERIALS
(2021)
Article
Crystallography
Yutaka Ohno, Tomio Kajigaya, Kazutaka Osako, Toshio Kochiya
Summary: The cracking process of 36-degree RY lithium tantalate (LiTaO3) single crystals during Czochralski (CZ) growth was examined. It was found that twin lamellae were generated beneath the -Z' surface of the ingots due to the dissociation of dislocations composing the lineages. Cracking occurred at the intersections where the twin lamellae grew with the CZ growth towards the bottom of the ingots.
JOURNAL OF CRYSTAL GROWTH
(2021)
Article
Physics, Applied
Jianbo Liang, Daiki Takatsuki, Masataka Higashiwaki, Yasuo Shimizu, Yutaka Ohno, Yasuyoshi Nagai, Naoteru Shigekawa
Summary: In this work, Ga2O3(001)/Si(100) and Ga2O3(010)/Si(100) heterointerfaces were fabricated through surface activated bonding at room temperature. The thermal stability of the heterointerfaces was investigated by heating the bonding samples at different temperatures and it was found that the heterointerface with a thin Si exhibited good thermal stability at 1000 degrees C. An intermediate layer was formed at both heterointerfaces, with the Ga2O3(001)/Si(100) heterointerface having a uniform thickness while the Ga2O3(010)/Si(100) heterointerface having a non-uniform thickness.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Ryo Kagawa, Keisuke Kawamura, Yoshiki Sakaida, Sumito Ouchi, Hiroki Uratani, Yasuo Shimizu, Yutaka Ohno, Yasuyoshi Nagai, Jianbo Liang, Naoteru Shigekawa
Summary: We have successfully fabricated AlGaN/GaN high electron mobility transistors (HEMTs) on diamond substrates, and found that the HEMTs on diamond have smaller negative drain conductance due to their lower thermal resistance. This implies that the bonding-first process is applicable for fabricating HEMTs with low thermal resistance and thick nitride layers.
APPLIED PHYSICS EXPRESS
(2022)
Article
Physics, Applied
Yutaka Ohno, Jianbo Liang, Hideto Yoshida, Yasuo Shimizu, Yasuyoshi Nagai, Naoteru Shigekawa
Summary: The chemical composition around diamond/silicon heterointerfaces fabricated through surface activated bonding (SAB) at room temperature was examined. Iron impurities were found to segregate at the bonding interfaces, while oxygen impurities were found to segregate off the bonding interfaces in the silicon side. When the bonding interfaces were annealed, the amorphous compound converted to cubic silicon carbide (c-SiC) and nano-voids were formed between silicon and c-SiC. These nano-voids acted as sites for metal impurities to agglomerate and helped to improve the electronic properties of the bonding interfaces through impurity gettering.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Yusuke Fukuda, Kentaro Kutsukake, Takuto Kojima, Yutaka Ohno, Noritaka Usami
Summary: This study investigates the effects of grain boundary structures on the carrier recombination velocity in multicrystalline silicon. The results show that the deviation angle from the ingot growth direction has a relatively large impact on the carrier recombination velocity. Additionally, it is found that grain boundaries with lower energy have lower carrier recombination velocity.
JOURNAL OF APPLIED PHYSICS
(2022)
Review
Physics, Applied
Naoteru Shigekawa, Jianbo Liang, Yutaka Ohno
Summary: Recent achievements in the research of heterojunctions fabricated using surface activated bonding (SAB) technology are discussed in this paper, with a focus on the response of bonding interfaces to post-bonding annealing. The study reveals that defect layers formed at the bonded interfaces can be improved and the heterojunctions exhibit high thermal tolerance. Characteristics of III-V//Si multijunction solar cells, GaN-on-diamond high electron mobility transistors, and metal-foil based low-loss interconnects that are fabricated by processing SAB-based junctions are described, along with future prospects.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Multidisciplinary Sciences
Zhe Cheng, Jianbo Liang, Keisuke Kawamura, Hao Zhou, Hidetoshi Asamura, Hiroki Uratani, Janak Tiwari, Samuel Graham, Yutaka Ohno, Yasuyoshi Nagai, Tianli Feng, Naoteru Shigekawa, David G. Cahill
Summary: In this study, the authors report isotropic high thermal conductivity of 3C-SiC wafers exceeding 500 W m(-1)K(-1). The material not only has high thermal conductivity, but also provides important insights into fundamental phonon transport mechanisms, making it an excellent material for next-generation power electronics.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Applied
Kazuki Sawai, Jianbo Liang, Yasuo Shimizu, Yutaka Ohno, Yasuyoshi Nagai, Naoteru Shigekawa
Summary: The electrical properties of group-III nitride heterojunctions are greatly affected by interface charges due to polarizations discontinuity. Ga-face/Ga-face and N-face/N-face interfaces with antiparallel spontaneous polarizations were fabricated using surface-activated bonding of double-side polished freestanding GaN (0001) wafers to investigate their electrical and nanostructural properties. After annealing at 600 degrees C, the built-in potential of the N-face/N-face interface is smaller than that of the Ga-face/Ga-face interface. The difference in built-in potentials between the two antiparallel polarized interfaces is analyzed using a charge-neutrality-level model and the density of interface states is roughly estimated. The leakage in both Ga-face/Ga-face and N-face/N-face interfaces is enhanced at higher annealing temperatures, suggesting the contribution of defects near the bonding interfaces.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Kenta Yamakoshi, Yutaka Ohno, Kentaro Kutsukake, Takuto Kojima, Tatsuya Yokoi, Hideto Yoshida, Hiroyuki Tanaka, Xin Liu, Hiroaki Kudo, Noritaka Usami
Summary: A comprehensive analysis of optical and photoluminescence images from multicrystalline silicon wafers is conducted using machine learning models, resulting in the establishment of a realistic 3D model that includes the generation point of dislocation clusters. The study reveals the mechanism of dislocation generation and its importance in materials science.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Ryo Kagawa, Zhe Cheng, Keisuke Kawamura, Yutaka Ohno, Chiharu Moriyama, Yoshiki Sakaida, Sumito Ouchi, Hiroki Uratani, Koji Inoue, Yasuyoshi Nagai, Naoteru Shigekawa, Jianbo Liang
Summary: This study demonstrates the potential of fabricating GaN HEMTs on diamond substrates by successfully transferring AlGaN/GaN/3C-SiC layers to large diamond substrates and maintaining the integrity and high thermal conductivity of the substrate interface. It enables high-quality crystal growth and excellent heat dissipation performance.
Article
Materials Science, Multidisciplinary
Yuya Hattori, Shunsuke Yoshizawa, Keisuke Sagisaka, Yuki Tokumoto, Keiichi Edagawa, Takako Konoike, Shinya Uji, Taichi Terashima
Summary: Scanning tunneling microscopy and transport measurements were used to investigate the electronic structure and temperature dependence in heavily Sr and Na codoped PbTe. The band gap increases with doping, leading to band convergence, which is desirable for thermoelectric materials. At higher temperatures, carrier redistribution occurs between different bands.
Article
Physics, Applied
Yutaka Ohno, Takehiro Tamaoka, Hideto Yoshida, Yasuo Shimizu, Kentaro Kutsukake, Yasuyoshi Nagai, Noritaka Usami
Summary: Research shows that non-coherent sigma 3{111} grain boundaries with a positive tilt angle deviation exhibit high recombination activity in high-performance multicrystalline silicon ingots. The presence of edge-type dislocations with a specific Burgers vector arrangement, along with stretched 110 reconstructed bonds to prevent dangling bonds, leads to the generation of large strains around dislocation cores. This strain-induced segregation of oxygen and carbon atoms is believed to be the main cause of the recombination activity.
APPLIED PHYSICS EXPRESS
(2021)