The structure analysis of amorphous materials still leaves much room for improvement. Owing to the lack of translational or rotational symmetry of amorphous materials, it is important to develop a different approach from that used for crystals for the structure analysis of amorphous materials. Here, the angstrom-beam electron diffraction method was used to obtain the local structure information of amorphous materials at a sub-nanometre scale. In addition, we discussed the relationship between the global and local diffraction intensities of amorphous structures, and verified the effectiveness of the proposed method through basic diffraction simulations. Finally, some applications of the proposed method to structural and functional amorphous materials are summarized.
{"title":"Local structure analysis of amorphous materials by angstrom-beam electron diffraction","authors":"Akihiko Hirata","doi":"10.1093/jmicro/dfaa075","DOIUrl":"10.1093/jmicro/dfaa075","url":null,"abstract":"The structure analysis of amorphous materials still leaves much room for improvement. Owing to the lack of translational or rotational symmetry of amorphous materials, it is important to develop a different approach from that used for crystals for the structure analysis of amorphous materials. Here, the angstrom-beam electron diffraction method was used to obtain the local structure information of amorphous materials at a sub-nanometre scale. In addition, we discussed the relationship between the global and local diffraction intensities of amorphous structures, and verified the effectiveness of the proposed method through basic diffraction simulations. Finally, some applications of the proposed method to structural and functional amorphous materials are summarized.","PeriodicalId":18515,"journal":{"name":"Microscopy","volume":"70 1","pages":"171-177"},"PeriodicalIF":1.8,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/jmicro/dfaa075","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38723444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Phase-shifting electron holography (PS-EH) is an interference transmission electron microscopy technique that accurately visualizes potential distributions in functional materials, such as semiconductors. In this paper, we briefly introduce the features of the PS-EH that overcome some of the issues facing the conventional EH based on Fourier transformation. Then, we present a high-precision PS-EH technique with multiple electron biprisms and a sample preparation technique using a cryo-focused-ion-beam, which are important techniques for the accurate phase measurement of semiconductors. We present several applications of PS-EH to demonstrate the potential in organic and inorganic semiconductors and then discuss the differences by comparing them with previous reports on the conventional EH. We show that in situ biasing PS-EH was able to observe not only electric potential distribution but also electric field and charge density at a GaAs p–n junction and clarify how local band structures, depletion layer widths and space charges changed depending on the biasing conditions. Moreover, the PS-EH clearly visualized the local potential distributions of two-dimensional electron gas layers formed at AlGaN/GaN interfaces with different Al compositions. We also report the results of our PS-EH application for organic electroluminescence multilayers and point out the significant potential changes in the layers. The proposed PS-EH enables more precise phase measurement compared to the conventional EH, and our findings introduced in this paper will contribute to the future research and development of high-performance semiconductor materials and devices.
{"title":"Phase-shifting electron holography for accurate measurement of potential distributions in organic and inorganic semiconductors","authors":"Kazuo Yamamoto;Satoshi Anada;Takeshi Sato;Noriyuki Yoshimoto;Tsukasa Hirayama","doi":"10.1093/jmicro/dfaa061","DOIUrl":"10.1093/jmicro/dfaa061","url":null,"abstract":"Phase-shifting electron holography (PS-EH) is an interference transmission electron microscopy technique that accurately visualizes potential distributions in functional materials, such as semiconductors. In this paper, we briefly introduce the features of the PS-EH that overcome some of the issues facing the conventional EH based on Fourier transformation. Then, we present a high-precision PS-EH technique with multiple electron biprisms and a sample preparation technique using a cryo-focused-ion-beam, which are important techniques for the accurate phase measurement of semiconductors. We present several applications of PS-EH to demonstrate the potential in organic and inorganic semiconductors and then discuss the differences by comparing them with previous reports on the conventional EH. We show that in situ biasing PS-EH was able to observe not only electric potential distribution but also electric field and charge density at a GaAs p–n junction and clarify how local band structures, depletion layer widths and space charges changed depending on the biasing conditions. Moreover, the PS-EH clearly visualized the local potential distributions of two-dimensional electron gas layers formed at AlGaN/GaN interfaces with different Al compositions. We also report the results of our PS-EH application for organic electroluminescence multilayers and point out the significant potential changes in the layers. The proposed PS-EH enables more precise phase measurement compared to the conventional EH, and our findings introduced in this paper will contribute to the future research and development of high-performance semiconductor materials and devices.","PeriodicalId":18515,"journal":{"name":"Microscopy","volume":"70 1","pages":"24-38"},"PeriodicalIF":1.8,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/jmicro/dfaa061","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38482800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Differential-phase-contrast scanning transmission electron microscopy (DPC STEM) is a technique to directly visualize local electromagnetic field distribution inside materials and devices at very high spatial resolution. Owing to the recent progress in the development of high-speed segmented and pixelated detectors, DPC STEM now constitutes one of the major imaging modes in modern aberration-corrected STEM. While qualitative imaging of electromagnetic fields by DPC STEM is readily possible, quantitative imaging by DPC STEM is still under development because of the several fundamental issues inherent in the technique. In this report, we review the current status and future prospects of DPC STEM for quantitative electromagnetic field imaging from atomic scale to mesoscopic scale.
{"title":"Toward quantitative electromagnetic field imaging by differential-phase-contrast scanning transmission electron microscopy","authors":"Takehito Seki;Yuichi Ikuhara;Naoya Shibata","doi":"10.1093/jmicro/dfaa065","DOIUrl":"10.1093/jmicro/dfaa065","url":null,"abstract":"Differential-phase-contrast scanning transmission electron microscopy (DPC STEM) is a technique to directly visualize local electromagnetic field distribution inside materials and devices at very high spatial resolution. Owing to the recent progress in the development of high-speed segmented and pixelated detectors, DPC STEM now constitutes one of the major imaging modes in modern aberration-corrected STEM. While qualitative imaging of electromagnetic fields by DPC STEM is readily possible, quantitative imaging by DPC STEM is still under development because of the several fundamental issues inherent in the technique. In this report, we review the current status and future prospects of DPC STEM for quantitative electromagnetic field imaging from atomic scale to mesoscopic scale.","PeriodicalId":18515,"journal":{"name":"Microscopy","volume":"70 1","pages":"148-160"},"PeriodicalIF":1.8,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/jmicro/dfaa065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38576141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accurate assessment of three-dimensional (3D) characteristics, such as the shape and size distribution, of discrete elements (e.g. particles, granules, grains, voids, crystals, cells and fibers) is required in various fields. But generally, in practice, two-dimensional (2D) instead of 3D assessment is conducted due to limitations in time, cost or measurement technology (as in microscopic observation of discrete elements). In this study, experimental validation was conducted for a 2D–3D conversion method, developed in 2018, which estimates multiple 3D parameters based on 2D counterparts, using an x-ray computed tomography analysis of silica sand. Six 3D parameters (volume, surface area, long-axis length, sphericity and long/middle and long/short axis ratios) were successfully estimated based on five measured 2D parameters (sectional area, perimeter, long-axis length, circularity and long/short axis ratio). An experimental validation was conducted for a 2D–3D conversion method, which estimates multiple 3D parameters based on 2D counterparts, using X-ray computed tomography analysis of silica sand. Six 3D parameters (volume, surface area, long-axis length, sphericity, long/middle and long/short axis ratio) were successfully estimated based on measured 2D parameters.
{"title":"Experimental validation of a 2D–3D conversion method for estimation of multiple 3D characteristics of discrete elements","authors":"Takao Ueda","doi":"10.1093/jmicro/dfz112","DOIUrl":"10.1093/jmicro/dfz112","url":null,"abstract":"Accurate assessment of three-dimensional (3D) characteristics, such as the shape and size distribution, of discrete elements (e.g. particles, granules, grains, voids, crystals, cells and fibers) is required in various fields. But generally, in practice, two-dimensional (2D) instead of 3D assessment is conducted due to limitations in time, cost or measurement technology (as in microscopic observation of discrete elements). In this study, experimental validation was conducted for a 2D–3D conversion method, developed in 2018, which estimates multiple 3D parameters based on 2D counterparts, using an x-ray computed tomography analysis of silica sand. Six 3D parameters (volume, surface area, long-axis length, sphericity and long/middle and long/short axis ratios) were successfully estimated based on five measured 2D parameters (sectional area, perimeter, long-axis length, circularity and long/short axis ratio). An experimental validation was conducted for a 2D–3D conversion method, which estimates multiple 3D parameters based on 2D counterparts, using X-ray computed tomography analysis of silica sand. Six 3D parameters (volume, surface area, long-axis length, sphericity, long/middle and long/short axis ratio) were successfully estimated based on measured 2D parameters.","PeriodicalId":18515,"journal":{"name":"Microscopy","volume":"69 1","pages":"37-43"},"PeriodicalIF":1.8,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/jmicro/dfz112","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37669470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cementocytes in cementum form a lacuna-canalicular network. However, the 3D ultrastructure and range of the cementocyte network are unclear. Here, the 3D ultrastructure of the cementocyte network at the interface between cementum and periodontal ligament (PDL) was investigated on the mesoscale using FIB/SEM tomography. The results revealed a cellular network of cementocytes and PDL cells. A previous histomorphological study revealed the osteocyte-osteoblast-PDL cellular network. We extended this knowledge and revealed the cementum-PDL-bone cellular network, which may orchestrate the remodeling and modification of periodontal tissue, using a suitable method for imaging of complex tissue. The 3D ultrastructure of the cementocyte architecture around the interface between cementum and periodontal ligament (PDL) was investigated using FIB/SEM tomography. As a result, we showed a cellular interconnection between cementocytes and PDL cells and revealed the cementum-PDL-bone cellular network, extending our previous morphological discovery of the osteocyte-osteoblast-PDL cellular network.
{"title":"Cellular network across cementum and periodontal ligament elucidated by FIB/SEM tomography","authors":"Shingo Hirashima;Keisuke Ohta;Tomonoshin Kanazawa;Akinobu Togo;Risa Tsuneyoshi;Jingo Kusukawa;Kei-ichiro Nakamura","doi":"10.1093/jmicro/dfz117","DOIUrl":"10.1093/jmicro/dfz117","url":null,"abstract":"Cementocytes in cementum form a lacuna-canalicular network. However, the 3D ultrastructure and range of the cementocyte network are unclear. Here, the 3D ultrastructure of the cementocyte network at the interface between cementum and periodontal ligament (PDL) was investigated on the mesoscale using FIB/SEM tomography. The results revealed a cellular network of cementocytes and PDL cells. A previous histomorphological study revealed the osteocyte-osteoblast-PDL cellular network. We extended this knowledge and revealed the cementum-PDL-bone cellular network, which may orchestrate the remodeling and modification of periodontal tissue, using a suitable method for imaging of complex tissue. The 3D ultrastructure of the cementocyte architecture around the interface between cementum and periodontal ligament (PDL) was investigated using FIB/SEM tomography. As a result, we showed a cellular interconnection between cementocytes and PDL cells and revealed the cementum-PDL-bone cellular network, extending our previous morphological discovery of the osteocyte-osteoblast-PDL cellular network.","PeriodicalId":18515,"journal":{"name":"Microscopy","volume":"69 1","pages":"53-58"},"PeriodicalIF":1.8,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/jmicro/dfz117","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37635747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}