Pub Date : 2025-11-06DOI: 10.1016/j.ultramic.2025.114268
Yu-Chen Yang , Tung-Huan Chou , Ya-Lan Hsu , Kun-Lin Lin , Zhiqiang Wang , Kuen-Hsing Lin
This study developed a simple femtosecond (fs)-laser-assisted focused ion beam (FIB) method for rapidly fabricating tip samples for atom probe tomography (APT). In this method, a microtip array is fabricated directly on a Si sample to avoid the use of conventional lift-out procedures. The proposed method comprises two steps: fs-laser ablation and Ga FIB annular milling. Fs-laser ablation results in the formation of a damaged amorphous layer; however, this layer is small, does not affect the results of APT, and can be removed through subsequent Ga FIB annular milling. APT analysis of a tip sample fabricated using the proposed approach confirmed the feasibility of the method. This method not only enhanced the stability of the tip sample but also had a considerably shorter sample preparation time compared with conventional Ga FIB and Xe FIB fabrication processes.
{"title":"Femtosecond-laser-assisted focused ion beam method for the fabrication of tip specimens for atom probe tomography","authors":"Yu-Chen Yang , Tung-Huan Chou , Ya-Lan Hsu , Kun-Lin Lin , Zhiqiang Wang , Kuen-Hsing Lin","doi":"10.1016/j.ultramic.2025.114268","DOIUrl":"10.1016/j.ultramic.2025.114268","url":null,"abstract":"<div><div>This study developed a simple femtosecond (fs)-laser-assisted focused ion beam (FIB) method for rapidly fabricating tip samples for atom probe tomography (APT). In this method, a microtip array is fabricated directly on a Si sample to avoid the use of conventional lift-out procedures. The proposed method comprises two steps: fs-laser ablation and Ga FIB annular milling. Fs-laser ablation results in the formation of a damaged amorphous layer; however, this layer is small, does not affect the results of APT, and can be removed through subsequent Ga FIB annular milling. APT analysis of a tip sample fabricated using the proposed approach confirmed the feasibility of the method. This method not only enhanced the stability of the tip sample but also had a considerably shorter sample preparation time compared with conventional Ga FIB and Xe FIB fabrication processes.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"280 ","pages":"Article 114268"},"PeriodicalIF":2.0,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518127","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 : 2025-11-03DOI: 10.1016/j.ultramic.2025.114267
Diederik Jan Maas
An electrostatic aberration corrector (AC), based on a quadrupole-octupole design, for a low voltage scanning electron microscope (LV-SEM) has been developed, integrated and tested in a modified commercial SEM for improving image quality. After quantitative assessment and adjustment of the chromatic aberration and qualitive adjustment of the spherical aberration, LV-SEM image resolution and contrast improved by almost a factor three. Some unavoidable electromagnetic interference (EMI) accounts for the difference between the experimentally demonstrated AC-SEM edge resolution of 3.0 nm at a beam energy of 1000 eV and the corresponding theoretical probe size of 2.2 nm. After cancelling the chromatic and spherical aberrations of the objective lens of a scanning electron microscope (SEM) the reachable image resolution is limited by spot blur due to EMI, higher order aberrations and, more fundamentally, by the interaction volume of the focused electron beam in a sample and beam-induced alterations to the sample. Furthermore, the practical performance of the purely electrostatic aberration corrector integrated into an AC-SEM is demonstrated on typical material and life science samples at a beam energy of 500 and 1000 eV. Whereas electro-magnetic aberration correctors struggle with re-alignment iterations after a beam energy change due to remanent magnetic fields, a purely electrostatic corrector is swiftly adjusted by proportional scaling of electrode voltages. In principle, an electrostatic corrector can also be applied to low-voltage ion microscopy.
Summarising, an easy-to-use purely electrostatic corrector has been developed which, after proper integration into a state-of-the-art SEM, is capable of delivering the ultimate low-voltage SEM images.
{"title":"An electrostatic aberration corrector for improved Low-Voltage SEM imaging","authors":"Diederik Jan Maas","doi":"10.1016/j.ultramic.2025.114267","DOIUrl":"10.1016/j.ultramic.2025.114267","url":null,"abstract":"<div><div>An electrostatic aberration corrector (AC), based on a quadrupole-octupole design, for a low voltage scanning electron microscope (LV-SEM) has been developed, integrated and tested in a modified commercial SEM for improving image quality. After quantitative assessment and adjustment of the chromatic aberration and qualitive adjustment of the spherical aberration, LV-SEM image resolution and contrast improved by almost a factor three. Some unavoidable electromagnetic interference (EMI) accounts for the difference between the experimentally demonstrated AC-SEM edge resolution of 3.0 nm at a beam energy of 1000 eV and the corresponding theoretical probe size of 2.2 nm. After cancelling the chromatic and spherical aberrations of the objective lens of a scanning electron microscope (SEM) the reachable image resolution is limited by spot blur due to EMI, higher order aberrations and, more fundamentally, by the interaction volume of the focused electron beam in a sample and beam-induced alterations to the sample. Furthermore, the practical performance of the purely electrostatic aberration corrector integrated into an AC-SEM is demonstrated on typical material and life science samples at a beam energy of 500 and 1000 eV. Whereas electro-magnetic aberration correctors struggle with re-alignment iterations after a beam energy change due to remanent magnetic fields, a purely electrostatic corrector is swiftly adjusted by proportional scaling of electrode voltages. In principle, an electrostatic corrector can also be applied to low-voltage ion microscopy.</div><div>Summarising, an easy-to-use purely electrostatic corrector has been developed which, after proper integration into a state-of-the-art SEM, is capable of delivering the ultimate low-voltage SEM images.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"280 ","pages":"Article 114267"},"PeriodicalIF":2.0,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145468577","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 : 2025-11-03DOI: 10.1016/j.ultramic.2025.114266
N.G. Rudawski, M.A. Downing
Amorphous Si (a-Si) evaporated using electron beam physical vapor deposition (EBPVD) was investigated as a protective coating for dual focused ion beam/scanning electron microscope (FIB/SEM) preparation of lamellae for scanning/transmission electron microscopy (S/TEM) analysis. EBPVD a-Si films were evaporated on polished, undoped (001) SrTiO3 substrates and then dual FIB/SEM was used to prepare lamellae for S/TEM analysis. It was revealed that the EBPVD a-Si coating suppressed charging-related instabilities during dual FIB/SEM preparation. Subsequent S/TEM analyses using TEM imaging, high-angle annular dark-field (HAADF) STEM imaging, and selected area electron diffraction revealed the EBPVD a-Si films deposit with a smooth surface, non-porous microstructure, and amorphous crystal structure, which ultimately results in high-quality lamellae with smooth, curtain-free sidewalls. High-resolution TEM and HAADF-STEM imaging also revealed that the EBPVD process did not damage the surface of the (001) SrTiO3 substrates and that EBPVD a-Si is robust to both O2-based plasma cleaning and typical high-dose electron irradiation performed during atomic-resolution elemental mapping using energy dispersive spectroscopy. It is thus demonstrated that EBPVD a-Si meets all requirements for an ideal protective coating for dual FIB/SEM preparation of high-quality lamellae for S/TEM analysis and is advantageous over all other coatings previously investigated in this capacity.
{"title":"Evaporated amorphous Si protective coatings for dual FIB/SEM preparation of high-quality lamellae for S/TEM analysis","authors":"N.G. Rudawski, M.A. Downing","doi":"10.1016/j.ultramic.2025.114266","DOIUrl":"10.1016/j.ultramic.2025.114266","url":null,"abstract":"<div><div>Amorphous Si (a-Si) evaporated using electron beam physical vapor deposition (EBPVD) was investigated as a protective coating for dual focused ion beam/scanning electron microscope (FIB/SEM) preparation of lamellae for scanning/transmission electron microscopy (S/TEM) analysis. EBPVD a-Si films were evaporated on polished, undoped (001) SrTiO<sub>3</sub> substrates and then dual FIB/SEM was used to prepare lamellae for S/TEM analysis. It was revealed that the EBPVD a-Si coating suppressed charging-related instabilities during dual FIB/SEM preparation. Subsequent S/TEM analyses using TEM imaging, high-angle annular dark-field (HAADF) STEM imaging, and selected area electron diffraction revealed the EBPVD a-Si films deposit with a smooth surface, non-porous microstructure, and amorphous crystal structure, which ultimately results in high-quality lamellae with smooth, curtain-free sidewalls. High-resolution TEM and HAADF-STEM imaging also revealed that the EBPVD process did not damage the surface of the (001) SrTiO<sub>3</sub> substrates and that EBPVD a-Si is robust to both O<sub>2</sub>-based plasma cleaning and typical high-dose electron irradiation performed during atomic-resolution elemental mapping using energy dispersive spectroscopy. It is thus demonstrated that EBPVD a-Si meets all requirements for an ideal protective coating for dual FIB/SEM preparation of high-quality lamellae for S/TEM analysis and is advantageous over all other coatings previously investigated in this capacity.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"280 ","pages":"Article 114266"},"PeriodicalIF":2.0,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145468576","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 : 2025-10-26DOI: 10.1016/j.ultramic.2025.114265
Alexander Reifsnyder , Mohamed Nawwar , Minyue Zhu , Joseph P. Heremans , Jordan A. Hachtel , David W. McComb
Magnons, quanta of spin wave excitations in magnetically ordered materials, have been identified as candidates for several potentially transformative technologies in recent years. Macroscopic techniques, such as neutron scattering or Raman spectroscopy, can be used to identify and analyze magnons, but provide relatively delocalized information about the sample. Understanding how the bonding and local structure of a material interacts with, and influences, the magnon population in a material is a crucial step toward the ability to produce any real-world application utilizing magnons. By leveraging the combined spatial resolution of scanning transmission electron microscopy (STEM) and the energy resolution of monochromated electron energy-loss spectroscopy (EELS) nanoscale analysis of magnons can be performed. While the weak interaction of magnons with the electron beam makes magnon EELS challenging on reasonable timescales, magnon-phonon coupling can be leveraged to understand magnons through their effect on the more easily measured phonons. Here, we examine yttrium iron garnet (YIG) flakes, and demonstrate non-linear, temperature-dependent shifts in the phonon frequencies, consistent with previously described magnon-phonon coupling effects. The ability to measure the temperature-dependence of vibrational frequencies with high precision in individual nanoscale flakes, demonstrates the ability to study magnon-phonon coupling in the STEM with unprecedented spatial resolution.
{"title":"Detecting Magnon-phonon coupling in yttrium iron garnet with variable temperature STEM-EELS","authors":"Alexander Reifsnyder , Mohamed Nawwar , Minyue Zhu , Joseph P. Heremans , Jordan A. Hachtel , David W. McComb","doi":"10.1016/j.ultramic.2025.114265","DOIUrl":"10.1016/j.ultramic.2025.114265","url":null,"abstract":"<div><div>Magnons, quanta of spin wave excitations in magnetically ordered materials, have been identified as candidates for several potentially transformative technologies in recent years. Macroscopic techniques, such as neutron scattering or Raman spectroscopy, can be used to identify and analyze magnons, but provide relatively delocalized information about the sample. Understanding how the bonding and local structure of a material interacts with, and influences, the magnon population in a material is a crucial step toward the ability to produce any real-world application utilizing magnons. By leveraging the combined spatial resolution of scanning transmission electron microscopy (STEM) and the energy resolution of monochromated electron energy-loss spectroscopy (EELS) nanoscale analysis of magnons can be performed. While the weak interaction of magnons with the electron beam makes magnon EELS challenging on reasonable timescales, magnon-phonon coupling can be leveraged to understand magnons through their effect on the more easily measured phonons. Here, we examine yttrium iron garnet (YIG) flakes, and demonstrate non-linear, temperature-dependent shifts in the phonon frequencies, consistent with previously described magnon-phonon coupling effects. The ability to measure the temperature-dependence of vibrational frequencies with high precision in individual nanoscale flakes, demonstrates the ability to study magnon-phonon coupling in the STEM with unprecedented spatial resolution.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"280 ","pages":"Article 114265"},"PeriodicalIF":2.0,"publicationDate":"2025-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145398509","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 : 2025-10-26DOI: 10.1016/j.ultramic.2025.114264
BG Mendis, SP Hayes, COG Williamson, K Dhamotharan, SJ Clark
Compton spectroscopy measures , the number density of occupied electronic states with momentum component . In a transmission electron microscope (TEM) Compton spectroscopy is performed by acquiring a momentum resolved, dark-field electron energy loss spectrum (EELS). Here it is shown that the Bethe ridge in a single energy filtered diffraction pattern can provide identical information. The energy filtered TEM (EFTEM) approach is more dose efficient, since all (projected) momenta are recorded in parallel. For weakly diffracting specimens, the profiles extracted using EFTEM are in reasonable agreement with dark-field EELS. Bragg diffraction and thermal diffuse scattering are known to introduce artefacts in Compton spectroscopy, and this is true for the EFTEM method as well. The artefacts can however be mitigated by analysing suitably thin specimens.
{"title":"Bethe ridge electron Compton spectroscopy","authors":"BG Mendis, SP Hayes, COG Williamson, K Dhamotharan, SJ Clark","doi":"10.1016/j.ultramic.2025.114264","DOIUrl":"10.1016/j.ultramic.2025.114264","url":null,"abstract":"<div><div>Compton spectroscopy measures <span><math><mrow><mi>J</mi><mo>(</mo><msub><mi>p</mi><mi>z</mi></msub><mo>)</mo></mrow></math></span>, the number density of occupied electronic states with momentum component <span><math><msub><mi>p</mi><mi>z</mi></msub></math></span>. In a transmission electron microscope (TEM) Compton spectroscopy is performed by acquiring a momentum resolved, dark-field electron energy loss spectrum (EELS). Here it is shown that the Bethe ridge in a single energy filtered diffraction pattern can provide identical <span><math><mrow><mi>J</mi><mo>(</mo><msub><mi>p</mi><mi>z</mi></msub><mo>)</mo></mrow></math></span> information. The energy filtered TEM (EFTEM) approach is more dose efficient, since all (projected) momenta <span><math><msub><mi>p</mi><mi>z</mi></msub></math></span> are recorded in parallel. For weakly diffracting specimens, the <span><math><mrow><mi>J</mi><mo>(</mo><msub><mi>p</mi><mi>z</mi></msub><mo>)</mo></mrow></math></span> profiles extracted using EFTEM are in reasonable agreement with dark-field EELS. Bragg diffraction and thermal diffuse scattering are known to introduce artefacts in Compton spectroscopy, and this is true for the EFTEM method as well. The artefacts can however be mitigated by analysing suitably thin specimens.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"280 ","pages":"Article 114264"},"PeriodicalIF":2.0,"publicationDate":"2025-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145398507","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 : 2025-10-25DOI: 10.1016/j.ultramic.2025.114263
Young-Hoon Kim , Fehmi Sami Yasin , Na Yeon Kim , Max Birch , Xiuzhen Yu , Akiko Kikkawa , Yasujiro Taguchi , Jiaqiang Yan , Miaofang Chi
Advances in cryogenic electron microscopy have opened new avenues for probing quantum phenomena in correlated materials. This study reports the installation and performance of a new side-entry condenZero cryogenic cooling system for JEOL (Scanning) Transmission Electron Microscopes (S/TEM), utilizing compressed liquid helium (LHe) and designed for imaging and spectroscopy at ultra-low temperatures. The system includes an external dewar mounted on a vibration-damping stage and a pressurized, low-noise helium transfer line with a remotely controllable needle valve, ensuring stable and efficient LHe flow with minimal thermal and mechanical noise. Performance evaluation demonstrates a stable base temperature of 4.37 K measured using a Cernox bare chip sensor on the holder with temperature fluctuations within ±0.004 K. Complementary in-situ electron energy-loss spectroscopy (EELS) via aluminum bulk plasmon analysis was used to measure the local specimen temperature and validate cryogenic operation during experiments. The integration of cryogenic cooling with other microscopy techniques, including electron diffraction and Lorentz TEM, was demonstrated by resolving charge density wave (CDW) transitions in NbSe2 using electron diffraction, and imaging nanometric magnetic skyrmions in MnSi via Lorentz TEM. This platform provides reliable cryogenic operation below 7 K, establishing a low-drift route for direct visualization of electronic and magnetic phase transformations in quantum materials.
{"title":"Ultralow-temperature cryogenic transmission electron microscopy using a new helium flow cryostat stage","authors":"Young-Hoon Kim , Fehmi Sami Yasin , Na Yeon Kim , Max Birch , Xiuzhen Yu , Akiko Kikkawa , Yasujiro Taguchi , Jiaqiang Yan , Miaofang Chi","doi":"10.1016/j.ultramic.2025.114263","DOIUrl":"10.1016/j.ultramic.2025.114263","url":null,"abstract":"<div><div>Advances in cryogenic electron microscopy have opened new avenues for probing quantum phenomena in correlated materials. This study reports the installation and performance of a new side-entry condenZero cryogenic cooling system for JEOL (Scanning) Transmission Electron Microscopes (S/TEM), utilizing compressed liquid helium (LHe) and designed for imaging and spectroscopy at ultra-low temperatures. The system includes an external dewar mounted on a vibration-damping stage and a pressurized, low-noise helium transfer line with a remotely controllable needle valve, ensuring stable and efficient LHe flow with minimal thermal and mechanical noise. Performance evaluation demonstrates a stable base temperature of 4.37 K measured using a Cernox bare chip sensor on the holder with temperature fluctuations within ±0.004 K. Complementary in-situ electron energy-loss spectroscopy (EELS) via aluminum bulk plasmon analysis was used to measure the local specimen temperature and validate cryogenic operation during experiments. The integration of cryogenic cooling with other microscopy techniques, including electron diffraction and Lorentz TEM, was demonstrated by resolving charge density wave (CDW) transitions in NbSe<sub>2</sub> using electron diffraction, and imaging nanometric magnetic skyrmions in MnSi via Lorentz TEM. This platform provides reliable cryogenic operation below 7 K, establishing a low-drift route for direct visualization of electronic and magnetic phase transformations in quantum materials.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"280 ","pages":"Article 114263"},"PeriodicalIF":2.0,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145398508","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 : 2025-10-19DOI: 10.1016/j.ultramic.2025.114262
Martin Folwarczny , Ao Li , Rushvi Shah , Aaron Chote , Alexandra C. Austin , Yimin Zhu , Gregory S. Rohrer , Michael A. Jackson , Souhardh Kotakadi , Katharina Marquardt
We present a method for obtaining qualitatively accurate grain boundary plane distributions (GBPD) for textured microstructures using a stereological calculation applied to two-dimensional electron backscatter diffraction (EBSD) orientation maps. Stereology, applied to 2D EBSD orientation maps, is currently the fastest method of obtaining GBPDs. Existing stereological methods are not directly applicable to textured microstructures because of the biased viewing perspectives for different grain boundary types supplied from a single planar orientation map. The method presented in this work successfully removes part of this bias by combining data from three orthogonal EBSD orientation maps for stereology. This is shown here to produce qualitatively correct GBPDs for heavily textured synthetic microstructures with hexagonal and tetragonal crystal symmetries. Synthetic microstructures were generated to compare the stereological GBPD to a known ground truth, as the true GBPD could be obtained from a triangular mesh of the full grain boundary network in 3D. The triangle mesh data contained all five macroscopic parameters to fully describe the grain boundary structure. It was observed that our stereological method overestimated the GBPD anisotropy. However, qualitative analysis of the GBPD remains useful. Furthermore, it was found that combining data from three orthogonal sections gives reliable results when sectioning the texture’s primary axes.
{"title":"Accurate grain boundary plane distributions for textured microstructures from stereological analysis of orthogonal two-dimensional electron backscatter diffraction orientation maps","authors":"Martin Folwarczny , Ao Li , Rushvi Shah , Aaron Chote , Alexandra C. Austin , Yimin Zhu , Gregory S. Rohrer , Michael A. Jackson , Souhardh Kotakadi , Katharina Marquardt","doi":"10.1016/j.ultramic.2025.114262","DOIUrl":"10.1016/j.ultramic.2025.114262","url":null,"abstract":"<div><div>We present a method for obtaining qualitatively accurate grain boundary plane distributions (GBPD) for textured microstructures using a stereological calculation applied to two-dimensional electron backscatter diffraction (EBSD) orientation maps. Stereology, applied to 2D EBSD orientation maps, is currently the fastest method of obtaining GBPDs. Existing stereological methods are not directly applicable to textured microstructures because of the biased viewing perspectives for different grain boundary types supplied from a single planar orientation map. The method presented in this work successfully removes part of this bias by combining data from three orthogonal EBSD orientation maps for stereology. This is shown here to produce qualitatively correct GBPDs for heavily textured synthetic microstructures with hexagonal and tetragonal crystal symmetries. Synthetic microstructures were generated to compare the stereological GBPD to a known ground truth, as the true GBPD could be obtained from a triangular mesh of the full grain boundary network in 3D. The triangle mesh data contained all five macroscopic parameters to fully describe the grain boundary structure. It was observed that our stereological method overestimated the GBPD anisotropy. However, qualitative analysis of the GBPD remains useful. Furthermore, it was found that combining data from three orthogonal sections gives reliable results when sectioning the texture’s primary axes.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"280 ","pages":"Article 114262"},"PeriodicalIF":2.0,"publicationDate":"2025-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145507336","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 : 2025-10-19DOI: 10.1016/j.ultramic.2025.114261
Prajakta Kokate , Yorrick Boeije , Ganbaatar Tumen-Ulzii , Julien Madéo , Michael K.L. Man , Samuel D. Stranks , Keshav M. Dani
Nanoscale defects in photovoltaic materials can significantly impact solar cell performances, and yet their small size and location at buried interfaces make them challenging to study. A nanoscale imaging technique capable of identifying different types of defect and assessing their impacts to device performance is highly desirable. Photoemission electron microscopy (PEEM) with low energy photons could provide the necessary resolution for such investigations. In this paper, we demonstrate the use of PEEM and photoemission spectroscopy techniques to investigate defects in perovskite films and evaluate the effect of ethylenediamine iodide (EDAI) surface passivation, one of the well-studied passivation techniques that is known to reduce open-circuit voltage losses and enhance power conversion efficiency. Photoemission spectra show that mid-gap defects are spatially distributed similarly in both passivated and unpassivated samples but exhibit significantly reduced photoemission intensity after passivation, indicating effective defect passivation. This reduction suggests that EDAI mitigates recombination losses, potentially improving device stability and efficiency. Additionally, we observe that these defects are active hole traps. Given the extreme sensitivity of perovskite to light exposure and the inherently low hole trapping signal (<5 %), we outline the methodology for extracting this very weak signal.
{"title":"Studying the effect of EDAI passivation on surface defects in triple cation mixed halide perovskite with PEEM","authors":"Prajakta Kokate , Yorrick Boeije , Ganbaatar Tumen-Ulzii , Julien Madéo , Michael K.L. Man , Samuel D. Stranks , Keshav M. Dani","doi":"10.1016/j.ultramic.2025.114261","DOIUrl":"10.1016/j.ultramic.2025.114261","url":null,"abstract":"<div><div>Nanoscale defects in photovoltaic materials can significantly impact solar cell performances, and yet their small size and location at buried interfaces make them challenging to study. A nanoscale imaging technique capable of identifying different types of defect and assessing their impacts to device performance is highly desirable. Photoemission electron microscopy (PEEM) with low energy photons could provide the necessary resolution for such investigations. In this paper, we demonstrate the use of PEEM and photoemission spectroscopy techniques to investigate defects in perovskite films and evaluate the effect of ethylenediamine iodide (EDAI) surface passivation, one of the well-studied passivation techniques that is known to reduce open-circuit voltage losses and enhance power conversion efficiency. Photoemission spectra show that mid-gap defects are spatially distributed similarly in both passivated and unpassivated samples but exhibit significantly reduced photoemission intensity after passivation, indicating effective defect passivation. This reduction suggests that EDAI mitigates recombination losses, potentially improving device stability and efficiency. Additionally, we observe that these defects are active hole traps. Given the extreme sensitivity of perovskite to light exposure and the inherently low hole trapping signal (<5 %), we outline the methodology for extracting this very weak signal.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"279 ","pages":"Article 114261"},"PeriodicalIF":2.0,"publicationDate":"2025-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145402055","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 : 2025-10-18DOI: 10.1016/j.ultramic.2025.114260
Xi Yang , Paul Denham , Atharva Kulkarni , Brian Schaap , Victor Smaluk , Tianyi Wang , Nathalie Bouet , Mourad Idir , Pietro Musumeci
In scanning transmission electron microscopy (STEM), spatial resolution is primarily influenced by the projected size of the electron probe within the specimen. In thin samples, a large semi-convergence angle enables a tightly focused beam and sub-nanometer resolution. However, in thick specimens, resolution is fundamentally limited by transverse beam broadening from multiple large-angle scattering events—for example, a probe with 10 mrad angular divergence can broaden by ∼100 nm over a 10 μm path. Since this broadening scales inversely with beam energy, MeV-STEM offers a promising route for high-resolution imaging in thick materials. To quantitatively assess this effect, we performed high-precision measurements at UCLA’s PEGASUS beamline, characterizing beam divergence and intensity profiles for 3–8 MeV electrons transmitted through a wedged-silicon sample of varying thickness. Our results reconcile discrepancies among analytical models and validate Monte Carlo simulations. We find that increasing beam energy from 3.0 to 5.8 MeV reduces angular broadening by a factor of 2.6, with diminishing returns observed at 7.6 MeV. These findings provide a quantitative framework for optimizing MeV-STEM parameters in high-resolution imaging of thick biological and microelectronic specimens, and for guiding beam energy selection in other advanced imaging modes beyond STEM.
{"title":"Experimental study of energy-dependent angular broadening of MeV electron beams for high-resolution imaging in thick samples","authors":"Xi Yang , Paul Denham , Atharva Kulkarni , Brian Schaap , Victor Smaluk , Tianyi Wang , Nathalie Bouet , Mourad Idir , Pietro Musumeci","doi":"10.1016/j.ultramic.2025.114260","DOIUrl":"10.1016/j.ultramic.2025.114260","url":null,"abstract":"<div><div>In scanning transmission electron microscopy (STEM), spatial resolution is primarily influenced by the projected size of the electron probe within the specimen. In thin samples, a large semi-convergence angle enables a tightly focused beam and sub-nanometer resolution. However, in thick specimens, resolution is fundamentally limited by transverse beam broadening from multiple large-angle scattering events—for example, a probe with 10 mrad angular divergence can broaden by ∼100 nm over a 10 μm path. Since this broadening scales inversely with beam energy, MeV-STEM offers a promising route for high-resolution imaging in thick materials. To quantitatively assess this effect, we performed high-precision measurements at UCLA’s PEGASUS beamline, characterizing beam divergence and intensity profiles for 3–8 MeV electrons transmitted through a wedged-silicon sample of varying thickness. Our results reconcile discrepancies among analytical models and validate Monte Carlo simulations. We find that increasing beam energy from 3.0 to 5.8 MeV reduces angular broadening by a factor of 2.6, with diminishing returns observed at 7.6 MeV. These findings provide a quantitative framework for optimizing MeV-STEM parameters in high-resolution imaging of thick biological and microelectronic specimens, and for guiding beam energy selection in other advanced imaging modes beyond STEM.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"279 ","pages":"Article 114260"},"PeriodicalIF":2.0,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363831","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 : 2025-10-10DOI: 10.1016/j.ultramic.2025.114249
C.W. Johnson , L. Hess , J. Schwede , A. Stibor
Electron beam sources are essential for a wide range of applications, including microscopy, high-energy physics, quantum science, spectroscopy, interferometry or sensors technology. However, conventional electron sources face critical limitations in energy spread, beam current, and stability, underscoring the need for advancements. In this study, we present and characterize a laser-stimulated electron beam source based on a titanium dioxide (TiO) surface on n-type doped silicon, coated with cesium (Cs) and barium oxide (BaO) to reduce the work function. This approach harnesses the surface photovoltage (SPV) phenomenon in an n-type semiconductor, wherein laser activation drives charge drift toward the surface, reducing band bending and further lowering the work function. The electrons are then extracted through low-voltage field emission. This mechanism is in contrast to established sources that rely on direct laser excitation through multi-photon absorption. Experimental investigations were conducted using a low-energy electron microscope (LEEM) and a custom field emitter characterization setup. By illuminating the TiO sample with laser wavelengths of 830 nm, 404 nm and 824 nm, and applying biased field emission between −35 and −100 eV, we achieved work functions below 1 eV, highly sensitive to surface preparation. The results demonstrate beam currents up to 30 nA, a clearly defined two-peak energy spectrum, and an energy distribution as narrow as 100 meV in the primary peak. These findings establish SPV as a promising alternative for generating electron beams with high current and narrow energy distributions, paving the way for innovative field emitter designs and applications.
{"title":"Laser-induced electron beam emission from titanium dioxide on silicon photocathodes treated with cesium and barium oxide","authors":"C.W. Johnson , L. Hess , J. Schwede , A. Stibor","doi":"10.1016/j.ultramic.2025.114249","DOIUrl":"10.1016/j.ultramic.2025.114249","url":null,"abstract":"<div><div>Electron beam sources are essential for a wide range of applications, including microscopy, high-energy physics, quantum science, spectroscopy, interferometry or sensors technology. However, conventional electron sources face critical limitations in energy spread, beam current, and stability, underscoring the need for advancements. In this study, we present and characterize a laser-stimulated electron beam source based on a titanium dioxide (TiO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>) surface on n-type doped silicon, coated with cesium (Cs) and barium oxide (BaO) to reduce the work function. This approach harnesses the surface photovoltage (SPV) phenomenon in an n-type semiconductor, wherein laser activation drives charge drift toward the surface, reducing band bending and further lowering the work function. The electrons are then extracted through low-voltage field emission. This mechanism is in contrast to established sources that rely on direct laser excitation through multi-photon absorption. Experimental investigations were conducted using a low-energy electron microscope (LEEM) and a custom field emitter characterization setup. By illuminating the TiO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> sample with laser wavelengths of 830 nm, 404 nm and 824 nm, and applying biased field emission between −35 and −100 eV, we achieved work functions below 1 eV, highly sensitive to surface preparation. The results demonstrate beam currents up to 30 nA, a clearly defined two-peak energy spectrum, and an energy distribution as narrow as 100 meV in the primary peak. These findings establish SPV as a promising alternative for generating electron beams with high current and narrow energy distributions, paving the way for innovative field emitter designs and applications.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"279 ","pages":"Article 114249"},"PeriodicalIF":2.0,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145347566","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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