Experiments within the scanning electron microscope (SEM) are increasingly being carried out to observe microstructural evolution under applied strain and/or temperature. In-situ experiments allow phenomena to be observed that would be missed during post-mortem analysis. However, in-situ experiments are traditionally limited by being very labour intensive with an operator required throughout, restricting experiments to what can be achieved within working hours. Here, we present a fully integrated, automated solution that can carry out complex experiments without user intervention. With this solution experiments can be programmed with specific experimental conditions such as strain and heating and cooling rates with data acquisition parameters to track and collect data across statistically relevant regions. Three case studies are presented to demonstrate the solution's flexibility: multi-region strain mapping during mechanical loading, chemical mapping of the dissolution and coarsening of phases at high temperature, and orientation mapping during mechanical loading to understand deformation and grain rotation.

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.

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.

Reflected and transmitted secondary electron images of SiN window are obtained in scanning electron microscopy (SEM) by using SEM and scanning transmission electron microscopy (STEM) holders. The figure of SiN window becomes distinguishable as the accelerating voltage increases. However, the brightness of SiN window relative to the surroundings in images for SEM and STEM holders is completely opposite. It changes from dark to bright, which means the number of detected secondary electron increases. The difference of the two kinds of image is caused by the fact that secondary electrons emitted from the bottom surface can also be detected when using STEM holder. The images are consistent with Monte Carlo simulation results. Image figures are sensitive to accelerating voltages and sample thicknesses. Therefore, more characteristics of thin sample could be analyzed via combining the two kinds of image.

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.

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.

Lorentz transmission electron microscopy (LTEM) is a powerful tool for high-resolution imaging of magnetic textures, including their dynamics under external stimuli and ultrafast nonequilibrium conditions. However, magnetic imaging is often hindered by non-magnetic diffraction contrast arising from inhomogeneous sample deformation or a non-parallel electron beam. In this study, we develop a precession LTEM system that can suppress diffraction contrast by changing the incident angle of the electron beam relative to the sample in a precessional manner. By comparing LTEM images acquired at different precession angles (θ), we show that diffraction contrast is significantly reduced with increasing θ. However, large θ values lead to an undesired broadening of the magnetic contrast, highlighting the importance of optimizing θ. Furthermore, defocus-dependent measurements reveal that magnetic contrast is particularly improved at small defocus values. These findings demonstrate the potential of precession LTEM as a powerful technique for studying magnetic dynamics.

Here, we evaluate multislice electron ptychography as a tool for depth-resolved atomic-resolution characterization of point defects, using silicon carbide as a case study. Through multislice electron scattering simulations and multislice ptychographic reconstructions, we investigate the phase contrast arising from individual silicon vacancies, antisite defects, and a wide range of substitutional transition metal dopants (V to W), as well as their potential detectability. Simulating defect types, positions, and microscope conditions, we show that isolated point defects can be located within a unit cell along the sample's depth. The influence of electron energy, dose, defocus, and convergence semi-angle is also explored to determine their role in governing defect contrast. These results guide experiments aimed at analyzing point defects using multislice electron ptychography.

Secondary electron (SE) imaging offers a powerful complementary capabilities to conventional scanning transmission electron microscopy (STEM) by providing surface-sensitive, pseudo-3D topographic information. However, contrast interpretation of such images remains empirical due to complex interactions of emitted SE with the magnetic field in the objective field of TEM. Here, we propose an analytical physical model that takes into account the physics of SE emission and interaction of the emitted SEs with magnetic field. This enables more reliable image interpretation and potentially lay the foundation for novel 3D surface reconstruction algorithms.

Atomic-scale imaging of radiation-sensitive materials has been a challenge for both materials science and life science. While low-dose transmission electron microscopy (TEM) is particularly useful for minimizing the radiation damage, the noisy images with poor resolution make it extremely difficult for the purpose of fine structure analysis. Here, this work presents a phase retrieval method to achieve high-quality atomic-scale imaging of radiation-sensitive materials under low-dose TEM conditions. By integrating neural fields (NF) with traditional exit wave reconstruction (EWR), it is able to reveal atomic details from limited low-dose experimental data. Taking the radiation-sensitive organic-inorganic hybrid halide perovskite CHNHPbI (MAPbI) as an example, the EWR-NF method demonstrates superior performance in reconstructing the pristine atomic structure using as few as just three low-dose images, which is beyond the limits of conventional methods. In this manner, EWR-NF enables higher temporal resolution to reveal intermediate states during irradiation-induced decomposition. An example of stacking of MAPbI with its as-decomposed product is shown. EWR-NF offers a promising tool for atomic-level structure analysis of sensitive halide perovskites and understanding irradiation-induced structure changes, with implications for a wide range of applications in materials science and beyond.

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 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.

Compton spectroscopy measures J(p), the number density of occupied electronic states with momentum component p. 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 J(p) information. The energy filtered TEM (EFTEM) approach is more dose efficient, since all (projected) momenta p are recorded in parallel. For weakly diffracting specimens, the J(p) 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.

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 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 substrates and that EBPVD a-Si is robust to both O-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.

The electron threshold energy (E) of a material is a critical parameter for anyone conducting research using transmission electron microscopy (TEM). For studies involving irradiation damage, the electron beam energy must exceed the material's E to enable in-situ electron irradiation experiments. In contrast, for researchers focused on microstructural characterization, it is essential to ensure that the beam energy remains below E to avoid electron-beam-induced radiation damage, which could compromise the accuracy and reliability of the TEM analysis. This study revisits the commonly used formula for calculating E, originally cited in the textbook by Williams and Carter, and identifies significant discrepancies when compared with experimental observations and the original formulation. A corrected formula is proposed and applied to compute E values for 81 elements using their minimum displacement energies (E). The results are presented in a periodic-table-based diagram, providing practical reference for selecting appropriate TEM accelerating voltages to either induce or avoid irradiation damage.

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.

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.

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.

We report on the development of a new 100 MHz high-speed scan controller for the electron microscope, using programmable hardware. By using a spiral scan pattern in order to work around the limitations of the scan coils, we show that this controller is able to acquire undistorted images with a frame time of 0.9 ms. The controller's scan signal and timing control is used to optimize regular (sawtooth) scanning, in order to reduce image distortions at high speeds. Finally, we implement a dose-driven acquisition method, which lowers the required dose and optimizes its distribution, while maintaining the contrast mechanism of the detector.

Surface physics play an outsized role in nanostructured electronic devices such as solar cells. Semiconductor nanowires are perfect candidates for advanced solar cells due to their outstanding light absorption properties and their flexibility in axially stacking materials of different doping and band gap. Due to nanowire geometry, however, their surfaces dominate device performance and at the same time are challenging to investigate. Kelvin probe force microscopy (KPFM), an atomic force microscopy (AFM)-based method, provides a unique structural and electrical characterization even in unconventional 3D geometries. We demonstrate a high-resolution, non-destructive AFM technique for directly measuring nanowires within an array and still on their growth substrate. This in situ approach ensures measurement integrity and relevance while preserving the structures for subsequent measurement and processing. When compared with electron beam-induced current, cross-sectional KPFM is both more surface sensitive and less destructive. Utilizing such a cross-sectional approach facilitates rapid and comprehensive characterization of nanoelectronic surfaces.

Atomic Force Microscopy (AFM), as a scanning probe microscopy technique, has been extensively utilized for nanoscale structural characterization, mechanical property quantification, and in-situ electromagnetic field measurements with high spatial resolution. However, the primary limitations hindering the widespread application of AFM include its relatively low scanning velocity, intricate parameter optimization requirements, and the necessity for highly skilled operators to achieve optimal imaging resolution. In this paper, a novel fuzzy amplitude-modulated PI (Proportional-Integral) control methodology is proposed for AFM adaptive control systems, incorporating dynamically adjusted proportional and integral gain parameters to effectively mitigate measurement inaccuracies. Experimental characterization demonstrates that the proposed fuzzy control scheme effectively confines amplitude error to approximately 60 pm under operational conditions of 10 Hz scan rate and 40 μm scan size. This methodology establishes a systematic framework for optimizing parameter configuration in AFM, while simultaneously addressing the critical challenge of achieving high-speed performance in scanning probe microscopy applications.

Magnetic structures down to the nanometer scale have drawn increasing attention due to their fundamental interests and potential applications. In general, the magnetic structure of a system tends to stay in the state with the lowest energy as different interactions compete with each other. Here we report the direct observation of a meta-stable Omega state with double vortices of the same circularity in a nanoscale Fe island on a W(110) substrate. The process indicates that this metastable state is formed by two isolated islands merging during annealing, while keeping their original vortex state. Micromagnetic simulations confirm the possibility of this metastable state.