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Nordahl G, Dagenborg S, Sørhaug J, Nord M. Exploring deep learning models for 4D-STEM-DPC data processing. Ultramicroscopy 2024; 267:114058. [PMID: 39388848 DOI: 10.1016/j.ultramic.2024.114058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 09/05/2024] [Accepted: 09/25/2024] [Indexed: 10/12/2024]
Abstract
For the study of magnetic materials at the nanoscale, differential phase contrast (DPC) imaging is a potent tool. With the advancements in direct detector technology, and consequent popularity gain for four-dimensional scanning transmission electron microscopy (4D-STEM), there has been an ongoing development of new and enhanced ways for STEM-DPC big data processing. Conventional algorithms are experimentally tailored, and so in this article we explore how supervised learning with convolutional neural networks (CNN) can be utilized for automated and consistent processing of STEM-DPC data. Two different approaches are investigated, one with direct tracking of the beam with regression analysis, and one where a modified U-net is used for direct beam segmentation as a pre-processing step. The CNNs are trained on experimentally obtained 4D-STEM data, enabling them to effectively handle data collected under similar instrument acquisition parameters. The model outputs are compared to conventional algorithms, particularly in how they process data in the presence of strong diffraction contrast, and how they affect domain wall profiles and width measurement.
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Affiliation(s)
- Gregory Nordahl
- Department of Physics, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
| | - Sivert Dagenborg
- Department of Physics, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
| | - Jørgen Sørhaug
- Department of Physics, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
| | - Magnus Nord
- Department of Physics, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway.
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2
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Zheng F, Li LJ. Microscopic characterizations for 2D material-based advanced electronics. Micron 2024; 187:103707. [PMID: 39277960 DOI: 10.1016/j.micron.2024.103707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Revised: 08/14/2024] [Accepted: 08/23/2024] [Indexed: 09/17/2024]
Abstract
Two-dimensional (2D) materials have gained significant attention as potential candidates for next-generation electronics, owing to their unique properties such as ultrathin layer thickness, mechanical flexibility, and tunable bandgaps. The distinctive characteristics of 2D materials necessitate the development of nanoscale advanced characterization methods. In this review, we explore the role of microscopy techniques in developing 2D materials-based electronics, from material synthesis and characterization to device performance and reliability. We address the applications of microscopies by delving into the perspectives of channel materials, metal contacts, dielectric materials, and device architectures. Additionally, we provide an outlook on the future directions and potential utilization of microscopy techniques in future 2D semiconductor industry.
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Affiliation(s)
- Fangyuan Zheng
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
| | - Lain-Jong Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.
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3
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Kohno Y, Seki T, Tsuruoka S, Ohya S, Shibata N. Magnetic field observation in a magnetic tunnel junction by scanning transmission electron microscopy. Microscopy (Oxf) 2024; 73:329-334. [PMID: 38155605 DOI: 10.1093/jmicro/dfad063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 11/30/2023] [Accepted: 12/21/2023] [Indexed: 12/30/2023] Open
Abstract
A magnetic tunnel junction (MTJ) consists of two ferromagnetic layers separated by a thin insulating layer. MTJs show tunnel magnetoresistance effect, where the resistance in the direction perpendicular to the insulator layer drastically changes depending on the magnetization directions (parallel or antiparallel) in the ferromagnetic layers. However, direct observation of local magnetizations inside MTJs has been challenging. In this study, we demonstrate direct observation of magnetic flux density distribution inside epitaxially grown Fe/MgO/Fe layers using differential phase contrast scanning transmission electron microscopy. By utilizing newly developed tilt-scan averaging system for suppressing diffraction contrasts, we clearly visualize parallel and antiparallel states of ferromagnetic layers at nanometer resolution.
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Affiliation(s)
- Yuji Kohno
- JEOL Ltd, 3-1-2, Musashino, Akishima, Tokyo 196-8558, Japan
| | - Takehito Seki
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-8656, Japan
- PRESTO, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan
| | - Shun Tsuruoka
- Department of Electrical Engineering and Information Systems, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Shinobu Ohya
- Department of Electrical Engineering and Information Systems, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Center for Spintronics Research Network (CSRN), School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Institute for Nano Quantum Information Electronics (NanoQuine), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-8656, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan
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4
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Katsumi Y, Gamo H, Motohisa J, Tomioka K. InP Crystal Phase Heterojunction Transistor with a Vertical Gate-All-Around Structure. ACS APPLIED MATERIALS & INTERFACES 2024; 16:30471-30477. [PMID: 38819142 PMCID: PMC11182027 DOI: 10.1021/acsami.4c00147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/09/2024] [Accepted: 05/22/2024] [Indexed: 06/01/2024]
Abstract
Crystal phase transitions can form a new type of heterojunction with different atomic arrangements in the same material: crystal phase heterojunction (CPHJ). The CPHJ has an inherently strong impact on band engineering without concerns over critical thicknesses with misfit dislocations and a semiconductor-metal transition. In-plane CPHJ was recently demonstrated in two-dimensional (2D) transition-metal dichalcogenide (TMD) materials and utilized for conventional planar field-effect transistor applications. However, scalability such as gate electrostatic control, miniaturization, and multigate structure have been limited because of the geometrical issue. Here, we demonstrated a transistor using the CPHJ with a vertical gate-all-around structure by forming a CPHJ in conventional III-V semiconductors. The CPHJ, composed of wurtzite InP nanowires with zincblende InP substrates, showed an atomically flat heterojunction without dislocations and indicated a Type-II band discontinuity across the junction. The CPHJ transistor had moderate to good gate electrostatic controllability with high on-state currents and transconductance. The CPHJ offer will provide a new switching mechanism and add a new junction and device design choice to the long history of transistors.
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Affiliation(s)
- Yu Katsumi
- Graduate
School of Information Science and Technology, Hokkaido University, North 14 West 9, Sapporo 060-0814, Japan
- Research
Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, North 13 West 8, Sapporo 060-0813, Japan
| | - Hironori Gamo
- Graduate
School of Information Science and Technology, Hokkaido University, North 14 West 9, Sapporo 060-0814, Japan
- Research
Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, North 13 West 8, Sapporo 060-0813, Japan
| | - Junichi Motohisa
- Graduate
School of Information Science and Technology, Hokkaido University, North 14 West 9, Sapporo 060-0814, Japan
- Research
Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, North 13 West 8, Sapporo 060-0813, Japan
| | - Katsuhiro Tomioka
- Graduate
School of Information Science and Technology, Hokkaido University, North 14 West 9, Sapporo 060-0814, Japan
- Research
Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, North 13 West 8, Sapporo 060-0813, Japan
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5
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Cooper D, Bruas L, Bryan M, Boureau V. Measuring electrical properties in semiconductor devices by pixelated STEM and off-axis electron holography (or convergent beams vs. plane waves). Micron 2024; 179:103594. [PMID: 38340549 DOI: 10.1016/j.micron.2024.103594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024]
Abstract
We demonstrate the use of both pixelated differential phase contrast (DPC) scanning transmission electron microscopy (STEM) and off-axis electron holography (EH) for the measurement of electric fields and assess the advantages and limitations of each technique when applied to technologically relevant samples. Three different types of samples are examined, firstly a simple highly-doped Si pn junction. Then a SiGe superlattice is examined to evaluate the effects of the mean inner potential on the measured signal. Finally, an InGaN/GaN microwire light-emitting diode (LED) device is examined which has a polarization field, variations of mean inner potential and a wurtzite crystal lattice. We discuss aspects such as spatial resolution and sensitivity, and the concept of pseudo-field is defined. However, the most important point is the need to limit the influence of diffraction contrast to obtain accurate measurements. In this respect, the use of a plane electron wave for EH is clearly beneficial when compared to the use of a convergent beam for pixelated DPC STEM.
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Affiliation(s)
- David Cooper
- Universite Grenoble Alpes, CEA, LETI, F-38000 Grenoble, France.
| | - Lucas Bruas
- Universite Grenoble Alpes, CEA, LETI, F-38000 Grenoble, France
| | - Matthew Bryan
- Universite Grenoble Alpes, CEA, LETI, F-38000 Grenoble, France
| | - Victor Boureau
- Universite Grenoble Alpes, CEA, LETI, F-38000 Grenoble, France; Interdisciplinary Center for Electron Microscopy, EPFL, 1015 Lausanne, Switzerland
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Ii S. Quantitative Characterization by Transmission Electron Microscopy and Its Application to Interfacial Phenomena in Crystalline Materials. MATERIALS (BASEL, SWITZERLAND) 2024; 17:578. [PMID: 38591374 PMCID: PMC10856096 DOI: 10.3390/ma17030578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/13/2024] [Accepted: 01/18/2024] [Indexed: 04/10/2024]
Abstract
This paper reviews quantitative characterization via transmission electron microscopy (TEM) and its application to interfacial phenomena based on the results obtained through the studies. Several signals generated by the interaction between the specimen and the electron beam with a probe size of less than 1 nm are utilized for a quantitative analysis, which yields considerable chemical and physical information. This review describes several phenomena near the interfaces, e.g., clear solid-vapor interface (surface) segregation of yttria in the zirconia nanoparticles by an energy-dispersive X-ray spectroscopy analysis, the evaluation of the local magnetic moment at the grain boundary in terms of electron energy loss spectroscopy equipped with TEM, and grain boundary character dependence of the magnetism. The direct measurement of the stress to the dislocation transferred across the grain boundary and the microstructure evolution focused on the grain boundary formation caused by plastic deformation are discussed as examples of material dynamics associated with the grain boundary. Finally, the outlook for future investigations of interface studies, including the recent progress, is also discussed.
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Affiliation(s)
- Seiichiro Ii
- Research Center for Structural Materials, National Institute for Materials Science (NIMS), Tsukuba 305-0047, Japan
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7
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Xu J, Xue XX, Shao G, Jing C, Dai S, He K, Jia P, Wang S, Yuan Y, Luo J, Lu J. Atomic-level polarization in electric fields of defects for electrocatalysis. Nat Commun 2023; 14:7849. [PMID: 38030621 PMCID: PMC10686988 DOI: 10.1038/s41467-023-43689-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 11/16/2023] [Indexed: 12/01/2023] Open
Abstract
The thriving field of atomic defect engineering towards advanced electrocatalysis relies on the critical role of electric field polarization at the atomic scale. While this is proposed theoretically, the spatial configuration, orientation, and correlation with specific catalytic properties of materials are yet to be understood. Here, by targeting monolayer MoS2 rich in atomic defects, we pioneer the direct visualization of electric field polarization of such atomic defects by combining advanced electron microscopy with differential phase contrast technology. It is revealed that the asymmetric charge distribution caused by the polarization facilitates the adsorption of H*, which originally activates the atomic defect sites for catalytic hydrogen evolution reaction (HER). Then, it has been experimentally proven that atomic-level polarization in electric fields can enhance catalytic HER activity. This work bridges the long-existing gap between the atomic defects and advanced electrocatalysis by directly revealing the angstrom-scale electric field polarization and correlating it with the as-tuned catalytic properties of materials; the methodology proposed here could also inspire future studies focusing on catalytic mechanism understanding and structure-property-performance relationship.
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Affiliation(s)
- Jie Xu
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang, 325035, China
| | - Xiong-Xiong Xue
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan, 411105, China
| | - Gonglei Shao
- Interdisciplinary Research Center for Sustainable Energy Science and Engineering (IRC4SE2), School of Chemical Engineering, Zhengzhou University, Zhengzhou, 450001, China.
| | - Changfei Jing
- Feringa Nobel Prize Scientist Joint Research Centre, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai, 200237, China
| | - Sheng Dai
- Feringa Nobel Prize Scientist Joint Research Centre, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai, 200237, China
| | - Kun He
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang, 325035, China
| | - Peipei Jia
- ShenSi Lab, Shenzhen Institute for Advanced Study, University of Electronic Science and Technology of China, Longhua District, Shenzhen, 518110, China
| | - Shun Wang
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang, 325035, China
| | - Yifei Yuan
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang, 325035, China.
| | - Jun Luo
- ShenSi Lab, Shenzhen Institute for Advanced Study, University of Electronic Science and Technology of China, Longhua District, Shenzhen, 518110, China.
| | - Jun Lu
- College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China.
- Quzhou Institute of Power Battery and Grid Energy Storage, Quzhou, Zhejiang, 324000, China.
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8
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Chao HY, Venkatraman K, Moniri S, Jiang Y, Tang X, Dai S, Gao W, Miao J, Chi M. In Situ and Emerging Transmission Electron Microscopy for Catalysis Research. Chem Rev 2023. [PMID: 37327473 DOI: 10.1021/acs.chemrev.2c00880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Catalysts are the primary facilitator in many dynamic processes. Therefore, a thorough understanding of these processes has vast implications for a myriad of energy systems. The scanning/transmission electron microscope (S/TEM) is a powerful tool not only for atomic-scale characterization but also in situ catalytic experimentation. Techniques such as liquid and gas phase electron microscopy allow the observation of catalysts in an environment conducive to catalytic reactions. Correlated algorithms can greatly improve microscopy data processing and expand multidimensional data handling. Furthermore, new techniques including 4D-STEM, atomic electron tomography, cryogenic electron microscopy, and monochromated electron energy loss spectroscopy (EELS) push the boundaries of our comprehension of catalyst behavior. In this review, we discuss the existing and emergent techniques for observing catalysts using S/TEM. Challenges and opportunities highlighted aim to inspire and accelerate the use of electron microscopy to further investigate the complex interplay of catalytic systems.
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Affiliation(s)
- Hsin-Yun Chao
- Center for Nanophase Materials Sciences, One Bethel Valley Road, Building 4515, Oak Ridge, Tennessee 37831-6064, United States
| | - Kartik Venkatraman
- Center for Nanophase Materials Sciences, One Bethel Valley Road, Building 4515, Oak Ridge, Tennessee 37831-6064, United States
| | - Saman Moniri
- Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, California 90095, United States
| | - Yongjun Jiang
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China
| | - Xuan Tang
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China
| | - Sheng Dai
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China
| | - Wenpei Gao
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jianwei Miao
- Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, California 90095, United States
| | - Miaofang Chi
- Center for Nanophase Materials Sciences, One Bethel Valley Road, Building 4515, Oak Ridge, Tennessee 37831-6064, United States
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