Pub Date : 2025-11-01Epub Date: 2025-07-21DOI: 10.1016/j.ultramic.2025.114208
Simon Gaebel , Hüseyin Çelik , Dirk Berger , Christoph T. Koch , Michael Lehmann , Tolga Wagner
Interference gating (iGate) has emerged as a valuable and instrumentally easy-to-implement technique for time-resolved electron holography, allowing the study of dynamic processes on the nanosecond scale. Traditionally, iGate has relied on noise-based control signals, which, while effective, present challenges in achieving high repetition rates due to the complexity of signal generation and transmission. In this work, a square-wave-based control signal for iGate is introduced, offering a simpler and more robust alternative. Experimental validation indicates that this approach maintains comparable performance to the noise-based signal while enabling an order-of-magnitude improvement in temporal resolution, reaching with our current instrumentation. This advancement holds promise for improved time-resolved investigations of ultrafast nanoscale phenomena in TEM, providing a low barrier to entry.
{"title":"Approaching one nanosecond temporal resolution with square-wave-based control signals for interference gating","authors":"Simon Gaebel , Hüseyin Çelik , Dirk Berger , Christoph T. Koch , Michael Lehmann , Tolga Wagner","doi":"10.1016/j.ultramic.2025.114208","DOIUrl":"10.1016/j.ultramic.2025.114208","url":null,"abstract":"<div><div>Interference gating (iGate) has emerged as a valuable and instrumentally easy-to-implement technique for time-resolved electron holography, allowing the study of dynamic processes on the nanosecond scale. Traditionally, iGate has relied on noise-based control signals, which, while effective, present challenges in achieving high repetition rates due to the complexity of signal generation and transmission. In this work, a square-wave-based control signal for iGate is introduced, offering a simpler and more robust alternative. Experimental validation indicates that this approach maintains comparable performance to the noise-based signal while enabling an order-of-magnitude improvement in temporal resolution, reaching <span><math><mrow><mtext>1.9</mtext><mspace></mspace><mtext>ns</mtext></mrow></math></span> with our current instrumentation. This advancement holds promise for improved time-resolved investigations of ultrafast nanoscale phenomena in TEM, providing a low barrier to entry.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114208"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144679807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01Epub Date: 2025-07-14DOI: 10.1016/j.ultramic.2025.114209
Karen L. Kavanagh
{"title":"Preface to the Proceedings of the Thirteenth International Workshop on Low Energy Electron Microscopy and Photoemission Electron Microscopy (LEEM/PEEM 13)","authors":"Karen L. Kavanagh","doi":"10.1016/j.ultramic.2025.114209","DOIUrl":"10.1016/j.ultramic.2025.114209","url":null,"abstract":"","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114209"},"PeriodicalIF":2.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144699612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01Epub Date: 2025-07-19DOI: 10.1016/j.ultramic.2025.114218
Janghyun Jo , Ivan Lazić , Eric G.T. Bosch , Stefano Vespucci , Giulio Pozzi , Rafal E. Dunin-Borkowski
Phase contrast techniques in the transmission electron microscope (TEM), such as off-axis electron holography (OAEH) and four-dimensional scanning TEM (4D-STEM), are widely utilized for mapping electromagnetic fields both within and surrounding nanoscale materials. In this study, the two techniques are used to measure long-range electrostatic potentials and electric fields generated by electrically-biased colinear conducting needles. The results are compared between the two techniques and with a theoretical model. The experimental measurements obtained using OAEH and 4D-STEM via differential phase contrast reveal discrepancies in the magnitudes and distributions of the electric fields surrounding the needles. A comparison of both approaches with a theoretical model reveals that the discrepancy results from perturbation of the reference wave in OAEH by the highly extended electric field outside the needles, leading to an underestimate of the electrostatic potential when using OAEH. In contrast, the 4D-STEM measurements are more directly interpretable. We provide a theoretical background for the OAEH results, which fully explains and supports the findings.
{"title":"Quantitative comparison of long-range electric field measurements using off-axis electron holography and 4D-STEM via differential phase contrast","authors":"Janghyun Jo , Ivan Lazić , Eric G.T. Bosch , Stefano Vespucci , Giulio Pozzi , Rafal E. Dunin-Borkowski","doi":"10.1016/j.ultramic.2025.114218","DOIUrl":"10.1016/j.ultramic.2025.114218","url":null,"abstract":"<div><div>Phase contrast techniques in the transmission electron microscope (TEM), such as off-axis electron holography (OAEH) and four-dimensional scanning TEM (4D-STEM), are widely utilized for mapping electromagnetic fields both within and surrounding nanoscale materials. In this study, the two techniques are used to measure long-range electrostatic potentials and electric fields generated by electrically-biased colinear conducting needles. The results are compared between the two techniques and with a theoretical model. The experimental measurements obtained using OAEH and 4D-STEM <em>via</em> differential phase contrast reveal discrepancies in the magnitudes and distributions of the electric fields surrounding the needles. A comparison of both approaches with a theoretical model reveals that the discrepancy results from perturbation of the reference wave in OAEH by the highly extended electric field outside the needles, leading to an underestimate of the electrostatic potential when using OAEH. In contrast, the 4D-STEM measurements are more directly interpretable. We provide a theoretical background for the OAEH results, which fully explains and supports the findings.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114218"},"PeriodicalIF":2.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144763608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01Epub Date: 2025-07-13DOI: 10.1016/j.ultramic.2025.114210
Ömer Koç , Benjamin M. Jenkins , Jack Haley , Christina Hofer , Martin S. Meier , Megan E. Jones , Robert W. Harrison , Michael Preuss , Michael P. Moody , Christopher R.M. Grovenor , Philipp Frankel
Specimen preparation is a key step in the characterisation of materials systems. For high-resolution characterisation techniques such as transmission electron microscopy (TEM) and atom probe tomography (APT), it is necessary to have a sample preparation method that creates the nano-scale samples required for analysis but does not significantly modify the initial microstructure.
The preparation of hexagonal close-packed materials by focussed ion beam milling (FIB) and electropolishing has previously been shown to be complicated by hydride formation. The formation of hydrides can be reduced by the application of cryogenic temperatures during the final stages of Ga+ ion FIB milling, which are often conducted at low accelerating voltages in order to minimise irradiation-induced damage.
Xe+ ion plasma FIBs are now commonly used in the preparation of samples due to their higher milling rates. However, the severity of the hydride formation in hexagonal close-packed materials during Xe+ ion milling is unclear. In this paper, we compare Xe+ and Ga+ FIB milling to prepare Zr samples at ambient and cryogenic temperatures. By studying TEM and APT samples, we are able to compare the levels of hydride formation after FIB preparation caused by the different preparation techniques. APT is used to estimate the levels of hydrogen in the samples. These results represent an important contribution to researchers who use FIB preparation to create TEM and APT specimens from hexagonal close-packed metals such as zirconium.
{"title":"Cryogenic sample preparation: Comparative analysis of Ga+ and Xe+ FIB milling for TEM and APT examination of zirconium","authors":"Ömer Koç , Benjamin M. Jenkins , Jack Haley , Christina Hofer , Martin S. Meier , Megan E. Jones , Robert W. Harrison , Michael Preuss , Michael P. Moody , Christopher R.M. Grovenor , Philipp Frankel","doi":"10.1016/j.ultramic.2025.114210","DOIUrl":"10.1016/j.ultramic.2025.114210","url":null,"abstract":"<div><div>Specimen preparation is a key step in the characterisation of materials systems. For high-resolution characterisation techniques such as transmission electron microscopy (TEM) and atom probe tomography (APT), it is necessary to have a sample preparation method that creates the nano-scale samples required for analysis but does not significantly modify the initial microstructure.</div><div>The preparation of hexagonal close-packed materials by focussed ion beam milling (FIB) and electropolishing has previously been shown to be complicated by hydride formation. The formation of hydrides can be reduced by the application of cryogenic temperatures during the final stages of Ga<sup>+</sup> ion FIB milling, which are often conducted at low accelerating voltages in order to minimise irradiation-induced damage.</div><div>Xe<sup>+</sup> ion plasma FIBs are now commonly used in the preparation of samples due to their higher milling rates. However, the severity of the hydride formation in hexagonal close-packed materials during Xe<sup>+</sup> ion milling is unclear. In this paper, we compare Xe<sup>+</sup> and Ga<sup>+</sup> FIB milling to prepare Zr samples at ambient and cryogenic temperatures. By studying TEM and APT samples, we are able to compare the levels of hydride formation after FIB preparation caused by the different preparation techniques. APT is used to estimate the levels of hydrogen in the samples. These results represent an important contribution to researchers who use FIB preparation to create TEM and APT specimens from hexagonal close-packed metals such as zirconium.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114210"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144665697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01Epub Date: 2025-07-12DOI: 10.1016/j.ultramic.2025.114206
Arno Annys, Hoelen L. Lalandec Robert, Saleh Gholam, Joke Hadermann, Jo Verbeeck
Pixelated detectors in scanning transmission electron microscopy (STEM) generate large volumes of data, often tens to hundreds of GB per scan. However, to make current advancements scalable and enable widespread adoption, it is essential to use the most efficient representation of an electron’s information. Event-driven direct electron detectors, such as those based on the Timepix3 chip, offer significant potential for electron microscopy, particularly for low-dose experiments and real-time data processing. In this study, we compare sparse and dense data representations in terms of their size and computational requirements across various 4D-STEM scenarios, including high-resolution imaging and nano-beam electron diffraction. The advantages of performing 4D-STEM in an event-driven mode – such as reduced requirements in memory, bandwidth, and computational demands – can only be fully leveraged if the entire acquisition and processing pipeline is optimized to work directly with the event format, avoiding intermediate dense representations. We introduce a framework designed for acquisition and processing based on this event format, and demonstrate live processing of event-driven 4D-STEM, including analytical ptychography.
{"title":"Removing constraints of 4D-STEM with a framework for event-driven acquisition and processing","authors":"Arno Annys, Hoelen L. Lalandec Robert, Saleh Gholam, Joke Hadermann, Jo Verbeeck","doi":"10.1016/j.ultramic.2025.114206","DOIUrl":"10.1016/j.ultramic.2025.114206","url":null,"abstract":"<div><div>Pixelated detectors in scanning transmission electron microscopy (STEM) generate large volumes of data, often tens to hundreds of GB per scan. However, to make current advancements scalable and enable widespread adoption, it is essential to use the most efficient representation of an electron’s information. Event-driven direct electron detectors, such as those based on the Timepix3 chip, offer significant potential for electron microscopy, particularly for low-dose experiments and real-time data processing. In this study, we compare sparse and dense data representations in terms of their size and computational requirements across various 4D-STEM scenarios, including high-resolution imaging and nano-beam electron diffraction. The advantages of performing 4D-STEM in an event-driven mode – such as reduced requirements in memory, bandwidth, and computational demands – can only be fully leveraged if the entire acquisition and processing pipeline is optimized to work directly with the event format, avoiding intermediate dense representations. We introduce a framework designed for acquisition and processing based on this event format, and demonstrate live processing of event-driven 4D-STEM, including analytical ptychography.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114206"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01Epub Date: 2025-07-27DOI: 10.1016/j.ultramic.2025.114219
Mariusz Gołębiowski , Piotr Dróżdż , Ryszard Zdyb
Using low energy electron microscopy we investigate the origin of the contrast between domains in a heterostructure composed of twisted two-dimensional antimonene layers. The contrast is observed in the bright-field microscopy mode under normal incidence of the electron beam. The heterostructure consists of a single-domain β phase grown on a top of two-domain α phase antimonene on a W(110) surface. We show that the observed contrast is due to the formation of two different moiré superlattices and it directly reflects the two-domain structure of α antimonene. We also demonstrate that the contrast depends on the relative symmetry and crystallography of two moiré patterns.
{"title":"Observation of domain morphology in twisted antimonene layers via moiré superlattice contrast with low energy electron microscopy","authors":"Mariusz Gołębiowski , Piotr Dróżdż , Ryszard Zdyb","doi":"10.1016/j.ultramic.2025.114219","DOIUrl":"10.1016/j.ultramic.2025.114219","url":null,"abstract":"<div><div>Using low energy electron microscopy we investigate the origin of the contrast between domains in a heterostructure composed of twisted two-dimensional antimonene layers. The contrast is observed in the bright-field microscopy mode under normal incidence of the electron beam. The heterostructure consists of a single-domain β phase grown on a top of two-domain α phase antimonene on a W(110) surface. We show that the observed contrast is due to the formation of two different moiré superlattices and it directly reflects the two-domain structure of α antimonene. We also demonstrate that the contrast depends on the relative symmetry and crystallography of two moiré patterns.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114219"},"PeriodicalIF":2.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144725136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01Epub Date: 2025-07-14DOI: 10.1016/j.ultramic.2025.114198
Joseph J. Webb , Richard Beanland , Rudolf A. Römer
We show how generative machine learning can be used for the rapid computation of strongly dynamical electron diffraction directly from crystal structures, specifically in large-angle convergent-beam electron diffraction (LACBED) patterns. We find that a conditional generative adversarial network can learn the connection between the projected potential from a cubic crystal’s unit cell and the corresponding LACBED pattern. Our model can generate diffraction patterns on a GPU many orders of magnitude faster than existing direct simulation methods. Furthermore, our approach can accurately retrieve the projected potential from diffraction patterns, opening a new approach for the inverse problem of determining crystal structure.
{"title":"Large-angle convergent-beam electron diffraction patterns via conditional generative adversarial networks","authors":"Joseph J. Webb , Richard Beanland , Rudolf A. Römer","doi":"10.1016/j.ultramic.2025.114198","DOIUrl":"10.1016/j.ultramic.2025.114198","url":null,"abstract":"<div><div>We show how generative machine learning can be used for the rapid computation of strongly dynamical electron diffraction directly from crystal structures, specifically in large-angle convergent-beam electron diffraction (LACBED) patterns. We find that a conditional generative adversarial network can learn the connection between the projected potential from a cubic crystal’s unit cell and the corresponding LACBED pattern. Our model can generate diffraction patterns on a GPU many orders of magnitude faster than existing direct simulation methods. Furthermore, our approach can accurately retrieve the projected potential from diffraction patterns, opening a new approach for the inverse problem of determining crystal structure.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114198"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01Epub Date: 2025-08-10DOI: 10.1016/j.ultramic.2025.114223
Ranhao Zhang , Yuan Shen , Xueming Li
A tomogram is reconstructed from the micrographs of the tilt series using cryo-electron tomography (cryoET). Reconstruction frequently integrates image processing steps, such as filtering and contrast transfer function (CTF) correction, to support the downstream analysis of cellular and viral structures. Most image processing steps are based on Fourier space analysis, which is theoretically more efficient to be implemented in Fourier space than in real space. However, the substantial dimensions of tomograms present significant challenges for reconstruction and processing in Fourier space. Consequently, real-space reconstruction is prevalent in current practice. In this study, we proposed a Fourier-space algorithm for tomogram reconstruction, named MUltiple Slice Technique (MUST). MUST considers a tomogram composed of multiple parallel slices, with each slice independently reconstructed in Fourier space. A weighting strategy was used to enable MUST to achieve reconstruction compatible with real-space methods, including weighted back-projection (WBP) and the simultaneous iterative reconstruction technique (SIRT). A three-dimensional CTF model was formulated as pairs of conjugate central paraboloids in Fourier space and subsequently implemented for CTF correction in MUST. Alias-free reconstruction and pixel-level parallel computation are key features of MUST, demonstrated through tomogram-based subtomogram averaging at near-atomic resolutions.
{"title":"Fourier-based multiple-slice reconstruction in cryo-electron tomography","authors":"Ranhao Zhang , Yuan Shen , Xueming Li","doi":"10.1016/j.ultramic.2025.114223","DOIUrl":"10.1016/j.ultramic.2025.114223","url":null,"abstract":"<div><div>A tomogram is reconstructed from the micrographs of the tilt series using cryo-electron tomography (cryoET). Reconstruction frequently integrates image processing steps, such as filtering and contrast transfer function (CTF) correction, to support the downstream analysis of cellular and viral structures. Most image processing steps are based on Fourier space analysis, which is theoretically more efficient to be implemented in Fourier space than in real space. However, the substantial dimensions of tomograms present significant challenges for reconstruction and processing in Fourier space. Consequently, real-space reconstruction is prevalent in current practice. In this study, we proposed a Fourier-space algorithm for tomogram reconstruction, named MUltiple Slice Technique (MUST). MUST considers a tomogram composed of multiple parallel slices, with each slice independently reconstructed in Fourier space. A weighting strategy was used to enable MUST to achieve reconstruction compatible with real-space methods, including weighted back-projection (WBP) and the simultaneous iterative reconstruction technique (SIRT). A three-dimensional CTF model was formulated as pairs of conjugate central paraboloids in Fourier space and subsequently implemented for CTF correction in MUST. Alias-free reconstruction and pixel-level parallel computation are key features of MUST, demonstrated through tomogram-based subtomogram averaging at near-atomic resolutions.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114223"},"PeriodicalIF":2.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144863736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01Epub Date: 2025-08-19DOI: 10.1016/j.ultramic.2025.114222
Florian Castioni , Patrick Quéméré , Sergi Cuesta , Vincent Delaye , Pascale Bayle-Guillemaud , Eva Monroy , Eric Robin , Nicolas Bernier
Recent advancements in high-resolution spectroscopy analyses within the scanning transmission electron microscope (STEM) have paved the way for measuring the concentration of chemical species in crystalline materials at the atomic scale. However, several artifacts complicate the direct interpretation of experimental data. For instance, in the case of energy-dispersive X-ray (EDX) spectroscopy, the linear dependency of local X-ray emission on composition is disrupted by channeling effects and cross-talk during electron beam propagation. To address these challenges, it becomes necessary to adopt an approach that combines experimental data with inelastic scattering simulations. This method aims to account for the effects of electron beam propagation on X-ray emission, essentially determining the quantity and the spatial origin of the collected signal. In this publication, we propose to assess the precision and sensitivity limits of this approach in a practical case study involving a focused ion beam (FIB)-prepared III-N multilayers device. The device features nominally pure ∼1.5-nm-wide GaN quantum wells surrounded by AlGaN barriers containing a low concentration of aluminum (∼5 at%). By employing atomic-scale EDX acquisitions based on the averaging of more than several thousand frames, calibrated factors combined with a multilayer X-ray absorption correction model for quantification, and by comparing the X-ray radiation obtained from the quantum well with a reference 10-nm-wide structure, we demonstrate that the quantitative impact of beam propagation on chemical composition can be precisely accounted for, resulting in a composition sensitivity at the atomic scale as low as 0.25 at%. Finally, practical aspects to achieve this high precision level are discussed, particularly in terms of inelastic multislice simulation, uncertainty determination, and sample quality.
{"title":"Impact of electron beam propagation on high-resolution quantitative chemical analysis of 1-nm-wide GaN/AlGaN quantum wells","authors":"Florian Castioni , Patrick Quéméré , Sergi Cuesta , Vincent Delaye , Pascale Bayle-Guillemaud , Eva Monroy , Eric Robin , Nicolas Bernier","doi":"10.1016/j.ultramic.2025.114222","DOIUrl":"10.1016/j.ultramic.2025.114222","url":null,"abstract":"<div><div>Recent advancements in high-resolution spectroscopy analyses within the scanning transmission electron microscope (STEM) have paved the way for measuring the concentration of chemical species in crystalline materials at the atomic scale. However, several artifacts complicate the direct interpretation of experimental data. For instance, in the case of energy-dispersive X-ray (EDX) spectroscopy, the linear dependency of local X-ray emission on composition is disrupted by channeling effects and cross-talk during electron beam propagation. To address these challenges, it becomes necessary to adopt an approach that combines experimental data with inelastic scattering simulations. This method aims to account for the effects of electron beam propagation on X-ray emission, essentially determining the quantity and the spatial origin of the collected signal. In this publication, we propose to assess the precision and sensitivity limits of this approach in a practical case study involving a focused ion beam (FIB)-prepared III-N multilayers device. The device features nominally pure ∼1.5-nm-wide GaN quantum wells surrounded by AlGaN barriers containing a low concentration of aluminum (∼5 at%). By employing atomic-scale EDX acquisitions based on the averaging of more than several thousand frames, calibrated <span><math><mrow><mi>ζ</mi></mrow></math></span> factors combined with a multilayer X-ray absorption correction model for quantification, and by comparing the X-ray radiation obtained from the quantum well with a reference 10-nm-wide structure, we demonstrate that the quantitative impact of beam propagation on chemical composition can be precisely accounted for, resulting in a composition sensitivity at the atomic scale as low as <span><math><mo>±</mo></math></span>0.25 at%. Finally, practical aspects to achieve this high precision level are discussed, particularly in terms of inelastic multislice simulation, uncertainty determination, and sample quality.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114222"},"PeriodicalIF":2.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144907274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have developed an operando laser-based photoemission electron microscope (laser-PEEM) with a ferroelectric characterization system. A Sawyer-Tower circuit was implemented to measure the polarization–voltage (P–V) characteristics of ferroelectric devices. Using this system, we successfully obtained the well-defined P–V hysteresis loops for a ferroelectric capacitor incorporating Hf0.5Zr0.5O2 (HZO), reproducing the typical field-cycling characteristics of HZO capacitors. After dielectric breakdown caused by field-cycling stress, we visualized a conduction filament through the top electrode without any destructive processing. Additionally, we successfully observed polarization contrast through the top electrode of an oxide semiconductor (InZnOx). These results indicate that our operando laser-PEEM system is a powerful tool for visualizing conduction filaments after dielectric breakdown, the ferroelectric polarization contrasts, and electronic state distribution of materials implemented in ferroelectric devices, including ferroelectric field-effect transistors and ferroelectric tunnel junctions.
{"title":"Breakdown and polarization contrasts in ferroelectric devices observed by operando laser-based photoemission electron microscopy with the AC/DC electrical characterization system","authors":"Hirokazu Fujiwara , Yuki Itoya , Masaharu Kobayashi , Cédric Bareille , Toshiyuki Taniuchi","doi":"10.1016/j.ultramic.2025.114221","DOIUrl":"10.1016/j.ultramic.2025.114221","url":null,"abstract":"<div><div>We have developed an <em>operando</em> laser-based photoemission electron microscope (laser-PEEM) with a ferroelectric characterization system. A Sawyer-Tower circuit was implemented to measure the polarization–voltage (<em>P</em>–<em>V</em>) characteristics of ferroelectric devices. Using this system, we successfully obtained the well-defined <em>P</em>–<em>V</em> hysteresis loops for a ferroelectric capacitor incorporating Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> (HZO), reproducing the typical field-cycling characteristics of HZO capacitors. After dielectric breakdown caused by field-cycling stress, we visualized a conduction filament through the top electrode without any destructive processing. Additionally, we successfully observed polarization contrast through the top electrode of an oxide semiconductor (InZnO<em><sub>x</sub></em>). These results indicate that our <em>operando</em> laser-PEEM system is a powerful tool for visualizing conduction filaments after dielectric breakdown, the ferroelectric polarization contrasts, and electronic state distribution of materials implemented in ferroelectric devices, including ferroelectric field-effect transistors and ferroelectric tunnel junctions.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114221"},"PeriodicalIF":2.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144840734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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