1
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Uzuhashi J, Ohkubo T, Hono K. An Automated Site-Specific Tip Preparation Method for Atom Probe Tomography Using Script-Controlled Focused Ion Beam/Scanning Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2024:ozae015. [PMID: 38442209 DOI: 10.1093/mam/ozae015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 01/26/2024] [Accepted: 02/13/2024] [Indexed: 03/07/2024]
Abstract
The automation of the atom probe tomography (APT) tip preparation using a focused ion beam (FIB) with a scanning electron microscopy (SEM) dual-beam system will certainly contribute to systematic APT research with higher throughput and reliability. While our previous work established a method to prepare tips with a specified tip curvature and taper angle automatically, by using script-controlled FIB/SEM, the technique has been expanded to automated "site-specific" tip preparation in the current work. The improved procedure can automatically detect not only the tip shape but also the interface position in the tip; thus, the new function allows for control of the tip apex position. In other words, automated "site-specific" tip preparations are possible. The details of the automation procedure and some experimental demonstrations, that is, a Pt cap on Si, InGaN-based MQWs, and a p-n junction of GaAs, are presented.
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Affiliation(s)
- Jun Uzuhashi
- Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan
| | - Tadakatsu Ohkubo
- Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan
| | - Kazuhiro Hono
- Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan
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2
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Chejarla VS, Ahmed S, Beyer A, Volz K. Quantification of Potential Drops Across Semiconductor Heterointerfaces Using 4D-STEM. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:330-331. [PMID: 37613207 DOI: 10.1093/micmic/ozad067.154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Varun Shankar Chejarla
- Philipps-University Marburg, Department of Physics and Materials Science Center, Marburg, Germany
| | - Shamail Ahmed
- Philipps-University Marburg, Department of Physics and Materials Science Center, Marburg, Germany
| | - Andreas Beyer
- Philipps-University Marburg, Department of Physics and Materials Science Center, Marburg, Germany
| | - Kerstin Volz
- Philipps-University Marburg, Department of Physics and Materials Science Center, Marburg, Germany
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3
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Beyer A, Munde MS, Firoozabadi S, Heimes D, Grieb T, Rosenauer A, Müller-Caspary K, Volz K. Quantitative Characterization of Nanometer-Scale Electric Fields via Momentum-Resolved STEM. NANO LETTERS 2021; 21:2018-2025. [PMID: 33621104 DOI: 10.1021/acs.nanolett.0c04544] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Most of today's electronic devices, like solar cells and batteries, are based on nanometer-scale built-in electric fields. Accordingly, characterization of fields at such small scales has become an important task in the optimization of these devices. In this study, with GaAs-based p-n junctions as the example, key characteristics such as doping concentrations, polarity, and the depletion width are derived quantitatively using four-dimensional scanning transmission electron microscopy (4DSTEM). The built-in electric fields are determined by the shift they introduce to the center-of-mass of electron diffraction patterns at subnanometer spatial resolution. The method is applied successfully to characterize two p-n junctions with different doping concentrations. This highlights the potential of this method to directly visualize intentional or unintentional nanoscale electric fields in real-life devices, e.g., batteries, transistors, and solar cells.
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Affiliation(s)
- Andreas Beyer
- Materials Science Centre and Department of Physics, Philipps University Marburg, Hans-Meerwein-Straße 6, Marburg 35032, Germany
| | - Manveer Singh Munde
- Materials Science Centre and Department of Physics, Philipps University Marburg, Hans-Meerwein-Straße 6, Marburg 35032, Germany
| | - Saleh Firoozabadi
- Materials Science Centre and Department of Physics, Philipps University Marburg, Hans-Meerwein-Straße 6, Marburg 35032, Germany
| | - Damien Heimes
- Materials Science Centre and Department of Physics, Philipps University Marburg, Hans-Meerwein-Straße 6, Marburg 35032, Germany
| | - Tim Grieb
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, Bremen 28359, Germany
| | - Andreas Rosenauer
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, Bremen 28359, Germany
| | - Knut Müller-Caspary
- Ernst Ruska-Center for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, RWTH Aachen University, II. Institute of Physics, Otto-Blumenthal-Straße, Aachen 52074, Germany
| | - Kerstin Volz
- Materials Science Centre and Department of Physics, Philipps University Marburg, Hans-Meerwein-Straße 6, Marburg 35032, Germany
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4
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Zhang C, Feng Y, Han Z, Gao S, Wang M, Wang P. Electrochemical and Structural Analysis in All-Solid-State Lithium Batteries by Analytical Electron Microscopy: Progress and Perspectives. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1903747. [PMID: 31660670 DOI: 10.1002/adma.201903747] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 09/14/2019] [Indexed: 06/10/2023]
Abstract
Advanced scanning transmission electron microscopy (STEM) and its associated instruments have made significant contributions to the characterization of all-solid-state (ASS) Li batteries, as these tools provide localized information on the structure, morphology, chemistry, and electronic state of electrodes, electrolytes, and their interfaces at the nano- and atomic scale. Furthermore, the rapid development of in situ techniques has enabled a deep understanding of interfacial dynamic behavior and heterogeneous characteristics during the cycling process. However, due to the beam-sensitive nature of light elements in the interphases, e.g., Li and O, thorough and reliable studies of the interfacial structure and chemistry at an ultrahigh spatial resolution without beam damage is still a formidable challenge. Herein, the following points are discussed: (1) the recent contributions of advanced STEM to the study of ASS Li batteries; (2) current challenges associated with using this method; and (3) potential opportunities for combining cryo-electron microscopy and the STEM phase contrast imaging techniques.
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Affiliation(s)
- Chunchen Zhang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Yuzhang Feng
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Zhen Han
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Si Gao
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Meiyu Wang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Peng Wang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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5
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Toyama S, Seki T, Anada S, Sasaki H, Yamamoto K, Ikuhara Y, Shibata N. Quantitative electric field mapping of a p-n junction by DPC STEM. Ultramicroscopy 2020; 216:113033. [PMID: 32570133 DOI: 10.1016/j.ultramic.2020.113033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/09/2020] [Accepted: 05/24/2020] [Indexed: 10/24/2022]
Abstract
Local electromagnetic fields in a specimen is measured at high spatial resolutions using differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM). According to previous studies, DPC signals can be quantified by measuring the center of mass of the diffraction pattern intensity and/or performing a deconvolution method based on a phase contrast transfer function (PCTF). However, when using a segmented detector, the field strength has been considerably underestimated for a very thick specimen. The main cause of the underestimation is assumed to be inelastic scattering, mainly bulk plasmon scattering. In this study, we develop a method to remove this inelastic scattering effect from segmented detector DPC signals by modifying the PCTF deconvolution method. Field quantification results using this new technique are compared with those using pixelated detector DPC and electron holography, and all results indicated good agreement within an error margin.
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Affiliation(s)
- Satoko Toyama
- Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Takehito Seki
- Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Satoshi Anada
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan
| | - Hirokazu Sasaki
- Advanced Technologies R&D Laboratories, Furukawa Electric Co., Ltd., Yokohama 220-0073, Japan
| | - Kazuo Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656, Japan; Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656, Japan; Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan.
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6
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Yamamoto K, Nakano K, Tanaka A, Honda Y, Ando Y, Ogura M, Matsumoto M, Anada S, Ishikawa Y, Amano H, Hirayama T. Visualization of different carrier concentrations in n-type-GaN semiconductors by phase-shifting electron holography with multiple electron biprisms. ACTA ACUST UNITED AC 2020; 69:1-10. [PMID: 31711167 DOI: 10.1093/jmicro/dfz037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 09/14/2019] [Accepted: 09/16/2019] [Indexed: 11/13/2022]
Abstract
Phase-shifting electron holography (PS-EH) using a transmission electron microscope (TEM) was applied to visualize layers with different concentrations of carriers activated by Si (at dopant levels of 1019, 1018, 1017 and 1016 atoms cm-3) in n-type GaN semiconductors. To precisely measure the reconstructed phase profiles in the GaN sample, three electron biprisms were used to obtain a series of high-contrast holograms without Fresnel fringes generated by a biprism filament, and a cryo-focused-ion-beam (cryo-FIB) was used to prepare a uniform TEM sample with less distortion in the wide field of view. All layers in a 350-nm-thick TEM sample were distinguished with 1.8-nm spatial resolution and 0.02-rad phase-resolution, and variations of step width in the phase profile (corresponding to depletion width) at the interfaces between the layers were also measured. Thicknesses of the active and inactive layers at each dopant level were estimated from the observed phase profile and the simulation of theoretical band structure. Ratio of active-layer thickness to total thickness of the TEM sample significantly decreased as dopant concentration decreased; thus, a thicker TEM sample is necessary to visualize lower carrier concentrations; for example, to distinguish layers with dopant concentrations of 1016 and 1015 atoms cm-3. It was estimated that sample thickness must be more than 700 nm to make it be possible to detect sub-layers by the combination of PS-EH and cryo-FIB.
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Affiliation(s)
- Kazuo Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587, Japan
| | - Kiyotaka Nakano
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587, Japan
| | - Atsushi Tanaka
- Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Yoshio Honda
- Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Yuto Ando
- Department of Electronics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Masaya Ogura
- Department of Electronics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Miko Matsumoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587, Japan
| | - Satoshi Anada
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587, Japan
| | - Yukari Ishikawa
- Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan.,Materials Research and Development Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587, Japan
| | - Hiroshi Amano
- Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan.,Akasaki Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Tsukasa Hirayama
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587, Japan.,Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
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7
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Anada S, Yamamoto K, Sasaki H, Shibata N, Matsumoto M, Hori Y, Kinugawa K, Imamura A, Hirayama T. Accurate measurement of electric potentials in biased GaAs compound semiconductors by phase-shifting electron holography. Microscopy (Oxf) 2019; 68:159-166. [PMID: 30452667 DOI: 10.1093/jmicro/dfy131] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 10/23/2018] [Accepted: 11/11/2018] [Indexed: 11/13/2022] Open
Abstract
The innate electric potentials in biased p- and n-type GaAs compound semiconductors and the built-in potential were successfully measured with high accuracy and precision by applying in situ phase-shifting electron holography to a wedge-shaped GaAs specimen. A cryo-focused-ion-beam system was used to prepare the 35°-wedge-shaped specimen with smooth surfaces for a precise measurement. The specimen was biased in a transmission electron microscope, and holograms with high-contrast interference fringes were recorded for the phase-shifting method. A clear phase image around the p-n junction was reconstructed even in a thick region (thickness of ~700 nm) at a spatial resolution of 1 nm and precision of 0.01 rad. The innate electric potentials of the unbiased p- and n-type layers were measured to be 12.96 ± 0.17 V and 14.43 ± 0.19 V, respectively. The built-in potential was determined to be 1.48 ± 0.02 V. In addition, the in situ biasing measurement revealed that the measured electric-potential difference between the p and n regions changed by an amount equal to the voltage applied to the specimen, which indicates that all of the external voltage was applied to the p-n junction and that no voltage loss occurred at the other regions.
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Affiliation(s)
- Satoshi Anada
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan
| | - Kazuo Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan
| | - Hirokazu Sasaki
- Advanced Technologies Research and Development Laboratories, Furukawa Electric Co. Ltd, 2-4-3 Okano, Nishi-ku, Yokohama, Japan
| | - Naoya Shibata
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan.,Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Miko Matsumoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan
| | - Yujin Hori
- Advanced Technologies Research and Development Laboratories, Furukawa Electric Co. Ltd, 2-4-3 Okano, Nishi-ku, Yokohama, Japan
| | - Kouhei Kinugawa
- Advanced Technologies Research and Development Laboratories, Furukawa Electric Co. Ltd, 2-4-3 Okano, Nishi-ku, Yokohama, Japan
| | - Akihiro Imamura
- Advanced Technologies Research and Development Laboratories, Furukawa Electric Co. Ltd, 2-4-3 Okano, Nishi-ku, Yokohama, Japan
| | - Tsukasa Hirayama
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Japan
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8
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Nomura Y, Yamamoto K, Hirayama T, Saitoh K. Electric shielding films for biased TEM samples and their application to in situ electron holography. Microscopy (Oxf) 2018; 67:178-186. [DOI: 10.1093/jmicro/dfy018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 03/21/2018] [Indexed: 12/29/2022] Open
Affiliation(s)
- Yuki Nomura
- Advanced Research Division, Panasonic Corporation, 3-1-1 Yagumo-Nakamachi, Moriguchi, Osaka 570-8501, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587, Japan
- Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Kazuo Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587, Japan
| | - Tsukasa Hirayama
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587, Japan
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Koh Saitoh
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
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9
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Li L, Hu X, Gao Y. Electron Holographic Study of Semiconductor Light-Emitting Diodes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:1701996. [PMID: 29205817 DOI: 10.1002/smll.201701996] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 10/01/2017] [Indexed: 06/07/2023]
Abstract
Semiconductor light-emitting diodes (LEDs), especially GaN-based heterostructures, are widely used in light illumination. The lack of inversion symmetry of wurtzite crystal structures and the lattice mismatch at heterointerfaces cause large polarization fields with contributions from both spontaneous polarization and piezoelectric polarization, which in turn results in obvious quantum confined stark effect. It is possible to alleviate this effect if the local electrostatic fields and band alignment induced charge redistribution can be quantitatively determined across the heterostructures. In this Concept, the applications of electron holography to investigate semiconductor LEDs are summarized. Following the off-axis electron holography scheme, the GaN-based LED heterostructures including InGaN/GaN-based quantum wells, other GaN-based quantum wells, and other forms of GaN-based LED materials are discussed, focusing on the local potential drops, polarization fields, and charge distributions. Moreover, GaAs-based LED heterostructures are briefly discussed. The in-line electron holography scheme emphasizes the capability of large area strain mapping across LED heterostructures with high spatial resolution and accuracy, which is combined with quantitative electrostatic measurements and other advanced transmission electron microscopy characterizations to provide an overall nanometer scale perspective of LED devices for further improvement in their electric and optical properties.
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Affiliation(s)
- Luying Li
- Center for Nanoscale Characterization & Devices (CNCD), Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, P. R. China
| | - Xiaokang Hu
- Center for Nanoscale Characterization & Devices (CNCD), Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, P. R. China
| | - Yihua Gao
- Center for Nanoscale Characterization & Devices (CNCD), Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, P. R. China
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10
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Measuring nanometre-scale electric fields in scanning transmission electron microscopy using segmented detectors. Ultramicroscopy 2017; 182:169-178. [DOI: 10.1016/j.ultramic.2017.07.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 06/28/2017] [Accepted: 07/02/2017] [Indexed: 11/18/2022]
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11
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Shibata N, Findlay SD, Matsumoto T, Kohno Y, Seki T, Sánchez-Santolino G, Ikuhara Y. Direct Visualization of Local Electromagnetic Field Structures by Scanning Transmission Electron Microscopy. Acc Chem Res 2017; 50:1502-1512. [PMID: 28677953 DOI: 10.1021/acs.accounts.7b00123] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The functional properties of materials and devices are critically determined by the electromagnetic field structures formed inside them, especially at nanointerface and surface regions, because such structures are strongly associated with the dynamics of electrons, holes and ions. To understand the fundamental origin of many exotic properties in modern materials and devices, it is essential to directly characterize local electromagnetic field structures at such defect regions, even down to atomic dimensions. In recent years, rapid progress in the development of high-speed area detectors for aberration-corrected scanning transmission electron microscopy (STEM) with sub-angstrom spatial resolution has opened new possibilities to directly image such electromagnetic field structures at very high-resolution. In this Account, we give an overview of our recent development of differential phase contrast (DPC) microscopy for aberration-corrected STEM and its application to many materials problems. In recent years, we have developed segmented-type STEM detectors which divide the detector plane into 16 segments and enable simultaneous imaging of 16 STEM images which are sensitive to the positions and angles of transmitted/scattered electrons on the detector plane. These detectors also have atomic-resolution imaging capability. Using these segmented-type STEM detectors, we show DPC STEM imaging to be a very powerful tool for directly imaging local electromagnetic field structures in materials and devices in real space. For example, DPC STEM can clearly visualize the local electric field variation due to the abrupt potential change across a p-n junction in a GaAs semiconductor, which cannot be observed by normal in-focus bright-field or annular type dark-field STEM imaging modes. DPC STEM is also very effective for imaging magnetic field structures in magnetic materials, such as magnetic domains and skyrmions. Moreover, real-time imaging of electromagnetic field structures can now be realized through very fast data acquisition, processing, and reconstruction algorithms. If we use DPC STEM for atomic-resolution imaging using a sub-angstrom size electron probe, it has been shown that we can directly observe the atomic electric field inside atoms within crystals and even inside single atoms, the field between the atomic nucleus and the surrounding electron cloud, which possesses information about the atomic species, local chemical bonding and charge redistribution between bonded atoms. This possibility may open an alternative way for directly visualizing atoms and nanostructures, that is, seeing atoms as an entity of electromagnetic fields that reflect the intra- and interatomic electronic structures. In this Account, the current status of aberration-corrected DPC STEM is highlighted, along with some applications in real material and device studies.
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Affiliation(s)
- Naoya Shibata
- Institute
of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
- Nanostructures
Research Laboratory, Japan Fine Ceramic Center, Nagoya 456-8587, Japan
| | - Scott D. Findlay
- School
of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia
| | - Takao Matsumoto
- Institute
of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | | | - Takehito Seki
- Institute
of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Gabriel Sánchez-Santolino
- Institute
of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC, Sor Juana Inés de la Cruz
3, 28049 Madrid, Spain
| | - Yuichi Ikuhara
- Institute
of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
- Nanostructures
Research Laboratory, Japan Fine Ceramic Center, Nagoya 456-8587, Japan
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12
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Yamamoto K, Iriyama Y, Hirayama T. Operando observations of solid-state electrochemical reactions in Li-ion batteries by spatially resolved TEM EELS and electron holography. Microscopy (Oxf) 2017; 66:50-61. [PMID: 27733434 DOI: 10.1093/jmicro/dfw043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 09/08/2016] [Indexed: 11/13/2022] Open
Abstract
All-solid-state Li-ion batteries having incombustible solid electrolytes are promising energy storage devices because they have significant advantages in terms of safety, lifetime and energy density. Electrochemical reactions, namely, Li-ion insertion/extraction reactions, commonly occur around the nanometer-scale interfaces between the electrodes and solid electrolytes. Thus, transmission electron microscopy (TEM) is an appropriate technique to directly observe such reactions, providing important information for understanding the fundamental solid-state electrochemistry and improving battery performance. In this review, we introduce two types of TEM techniques for operando observations of battery reactions, spatially resolved electron energy-loss spectroscopy in a TEM mode for direct detection of the Li concentration profiles and electron holography for observing the electric potential changes due to Li-ion insertion/extraction reactions. We visually show how Li-ion insertion/extractions affect the crystal structures, electronic structures, and local electric potential during the charge-discharge processes in these batteries.
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Affiliation(s)
- Kazuo Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi456-8587, Japan
| | - Yasutoshi Iriyama
- Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi464-8601, Japan
| | - Tsukasa Hirayama
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi456-8587, Japan
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Shibata N, Findlay SD, Sasaki H, Matsumoto T, Sawada H, Kohno Y, Otomo S, Minato R, Ikuhara Y. Imaging of built-in electric field at a p-n junction by scanning transmission electron microscopy. Sci Rep 2015; 5:10040. [PMID: 26067359 PMCID: PMC4464396 DOI: 10.1038/srep10040] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 03/16/2015] [Indexed: 11/23/2022] Open
Abstract
Precise measurement and characterization of electrostatic potential structures and the concomitant electric fields at nanodimensions are essential to understand and control the properties of modern materials and devices. However, directly observing and measuring such local electric field information is still a major challenge in microscopy. Here, differential phase contrast imaging in scanning transmission electron microscopy with segmented type detector is used to image a p-n junction in a GaAs compound semiconductor. Differential phase contrast imaging is able to both clearly visualize and quantify the projected, built-in electric field in the p-n junction. The technique is further shown capable of sensitively detecting the electric field variations due to dopant concentration steps within both p-type and n-type regions. Through live differential phase contrast imaging, this technique can potentially be used to image the electromagnetic field structure of new materials and devices even under working conditions.
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Affiliation(s)
- Naoya Shibata
- 1] Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-8656, Japan [2] Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Scott D Findlay
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
| | - Hirokazu Sasaki
- Furukawa Electric Ltd., 2-4-3 Okano, Nishi-ku, Yokohama, 220-0073, Japan
| | - Takao Matsumoto
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-8656, Japan
| | | | - Yuji Kohno
- JEOL Ltd., 1-2-3 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Shinya Otomo
- Furukawa Electric Ltd., 2-4-3 Okano, Nishi-ku, Yokohama, 220-0073, Japan
| | - Ryuichiro Minato
- Furukawa Electric Ltd., 2-4-3 Okano, Nishi-ku, Yokohama, 220-0073, Japan
| | - Yuichi Ikuhara
- 1] Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-8656, Japan [2] Nanostructures Research Laboratory, Japan Fine Ceramic Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan
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