High-Resolution STEM Imaging | Features | Thermo Fisher Scientific

Explore flexible TEM capabilities for high-resolution imaging and spectroscopy

Thermo Scientific transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) systems are designed to support a wide range of advanced materials analysis workflows. From high-energy-resolution sources and atomic-scale STEM imaging to integrated EELS and EDS spectroscopy, these features enable researchers to investigate structure, composition, and electronic properties with precision. With flexible configurations, including X-FEG and X-CFEG sources, advanced detectors such as EMPAD, and Velox Software for streamlined data acquisition and analysis, these systems help you adapt to evolving research needs while maintaining consistent, high-quality results.

High-energy-resolution sources

The Iliad (S)TEM can be optionally equipped with either a high-energy-resolution extreme field emission gun (X-FEG)/Mono or an ultra-high-energy resolution X-FEG/UltiMono. The monochromators of both sources are automatically excited and tuned with single-click operation to achieve the highest energy resolution possible on each configuration by using OptiMono or OptiMono+ respectively (see video below).

The X-FEG/Mono can be automatically tuned from 1 eV down to 0.2 eV, while the X-FEG/UltiMono can be automatically tuned from 1 eV down to <30 meV.

Both sources can be operated from 30 – 300 kV to accommodate the widest range of specimens. Both can also be run in standard mode, with the monochromators switched off, to accommodate experiments that require high brightness, including STEM EDS mapping, ultra-high-resolution STEM, or high total current, such as TEM imaging, all with no compromise to the other specifications of the system. This flexibility gives the Spectra 300 (S)TEM the capability to function in settings where a large range of experiments are expected to be performed on one system.

Cold field emission gun (X-CFEG)

The Iliad (S)TEM can optionally be powered by a new cold field emission gun (X-CFEG). The X-CFEG has extremely high brightness (>>1.0 x 108 A/m2/Sr/V*), low energy spread (<0.4 eV), and can operate from 30 – 300 kV. This provides simultaneously high-resolution STEM imaging with high probe currents for high throughput, fast acquisition STEM analytics in parallel with high-energy resolution. With the powerful combination of X-CFEG and the S-CORR probe aberration corrector, sub-Angstrom (<0.8 Å) STEM-imaging resolution with over 1000 pA of probe current can be routinely achieved.

Further, probe currents can be flexibly tuned from <1 pA up to the nA range with fine control of the gun and condenser optics, all with minimum impact on the probe aberrations, so that the widest range of specimens and experiments can be accommodated.

As with all cold field emission sources, the sharp tip requires a periodic regeneration (called flashing) to maintain the probe current. With the X-CFEG, the tip only requires flashing once per working day, a process takes less than a minute. There is no measurable impact on the probe aberrations even in the highest resolution imaging conditions, and the daily tip flashing process has no impact on the tip lifetime.

Si[110] HAADF images taken with the X-CFEG/S-CORR combination; probe currents range from 0.016 nA (left) up to 1 nA (right) while maintaining <76 pm STEM resolution.

The energy resolution of the ultra-high brightness X-CFEG can be adjusted using the extraction voltage. In the case above it was varied between 0.39eV (with <500pA of probe current) and 0.31eV (with >300pA of probe current). The spatial resolution, as demonstrated in the HAADF image of DyScO3, remains unaffected (in this case <63pA). Sample courtesy Professor L.F. Kourkoutis, Cornell University

This new generation X-CFEG also produces enough total beam current (>14 nA) to support standard TEM imaging experiments (e.g. in situ) with large parallel probes, making it a uniquely all-purpose, yet high performance, C-FEG.

Adding to the flexible nature of the X-CFEG is the capability to adjust the energy resolution by varying the extraction voltage.

In the example below, the energy resolution was adjusted between 0.39eV, with <500pA of probe current and 0.31eV, with >300pA of probe current. Maintaining high probe currents with high energy resolution allows for detailed analysis of Energy Loss Near Edge Structure (ELNES) analysis without the need for a monochromator on core loss edges. The spatial resolution, as demonstrated in the HAADF image of DyScO3, remains unaffected (in this case <63pA) which means that STEM EELS experiments with simultaneously high spatial resolution, energy resolution and signal to noise ratio can now be performed.

The lifetime of the tip is unaffected by the extraction voltage chosen to perform the experiment.

STEM imaging performance

The combination of enhanced mechanical stability, the latest 5th-order probe aberration correction and the high-resolution (S-TWIN) wide-gap pole piece results in an instrument with the highest commercially-available STEM resolution specifications.

The Spectra 300 (S)TEM, with X-FEG/Mono or X-FEG/UltiMono, offers STEM resolution specifications of 50 pm at 300 kV, 96 pm at 60 kV and 125 pm at 30 kV with 30 pA of probe current or 100 pA with the X-CFEG.

Ultra-high resolution HAADF STEM imaging on a Spectra 300 (S)TEM. GaN[212] imaged at 300 kV with 40.5 pm Ga-Ga dumbells resolved as well as 39 pm resolution in the FFT. The image was collected on a wide gap S-TWIN pole piece with 30 pA of probe current.

Panther STEM detection system

STEM imaging on the Iliad (S)TEM has been reimagined with the Panther STEM detection system, which includes a new data acquisition architecture and two new, solid state, eight-segment ring and disk STEM detectors (16 segments in total). The new detector geometry offers access to advanced STEM imaging capability combined with the sensitivity to measure single electrons.

The 16 segmented ring and disk detectors of the Panther STEM detection system allow for a range of STEM signals without the need for multiple detectors.

Comparison SrTiO₃ [001] HAADF images taken with the Panther STEM detection system with 3 pA, 1.3 pA and <1 pA of probe current. Even with probe currents <1 pA, the signal-to-noise ratio in the image allows automation routines like OptiSTEM+ to correct 1st and 2nd order aberrations in the probe forming optics, delivering sharp images.

The entire signal chain is optimized and tuned to provide unprecedented signal-to-noise imaging capability with extremely low doses to facilitate imaging of beam sensitive materials. Additionally, the completely redeveloped data acquisition infrastructure can combine different individual detector segments, with the future possibility of combining detector segments in arbitrary ways, generating new STEM imaging methods and revealing information that is not present in conventional STEM techniques. The architecture is also scalable and provides an interface to synchronize multiple STEM and spectroscopic signals.

Extreme low-dose imaging of the metal organic framework (MOF) UiO 66 on the Spectra 300 (S)TEM. A probe current of <0.5 pA was used in combination with iDPC and the Panther STEM detection system to image atomic level details in this highly dose-sensitive material with a spatial resolution of 1.4 Å. The image is a single shot with a frame time of 23.5 seconds (Specimen courtesy of Professor Y. Han, King Abdullah University of Science and Technology).

EMPAD Electron Microscope Pixel Array detector

The Iliad (S)TEM can be configured with an electron microscope pixel array detector (EMPAD) or a Thermo Scientific Ceta Camera with speed enhancement to collect 4D STEM data sets.

The EMPAD is capable of 30-300 kV and provides a high dynamic range (1:1,000,000 e- between pixels), high signal-to-noise ratio (1/140 e-), and high speed (1100 frames per second) on a 128 x 128 pixel array, which makes it the optimal detector for 4D STEM applications. (E.g. Applications where the details of the central and diffracted beams need to be analyzed simultaneously, as in the following ptychography image.)

The Ceta Camera with speed enhancement offers an alternative for 4D STEM applications where a greater number of pixels is required and when EDS analysis needs to be combined with each point in the STEM scan. This solution provides higher resolution diffraction patterns (up to 512 x 512 pixel resolution), suited for applications such as strain measurement.

The EMPAD detector can be used for a wide variety of applications. On the left, it is used to extend spatial resolution (0.39 Å) beyond the aperture limited resolution at low accelerating voltages (80 kV) in a bi-layer of the 2D material MoS₂ ( Jiang, Y. et al. Nature 559, 343–349, 2018). On the right, it is used to independently image dark field reflections, revealing the complex microstructure of the precipitates in a superalloy (Sample courtesy Professor G. Burke, University of Manchester).

More details can be found in the EMPAD datasheet

Super-X detector

From high-throughput, high signal-to-noise ratio elemental mapping in EDS and EELS to oxidation state and surface phonon probing with ultra-high-resolution EELS, the Spectra 300 (S)TEM offers the spectroscopic flexibility to accommodate the widest range of analytical requirements.

The Spectra 300 (S)TEM can be configured with your choice of three different sources with varying energy resolution (X-FEG Mono, X-FEG UltiMono, and X-CFEG), two different EDS detector geometries (Super-X and Dual-X), and a range of Gatan Continuum spectrometers and energy filters, providing you with the freedom to configure the systems to suit your research needs.

The Thermo Scientific EDS detector portfolio provides a choice of detector geometries to suit your experimental requirements and optimize EDS results. Both configurations have a symmetric design, producing quantifiable data. Note that holder shadowing as a function of tilt is compensated in both detector configurations via built-in Thermo Scientific Velox Software functionality.

The Spectra 300 (S)TEM can be configured with either Super-X (for spectrum cleanliness and quantification) or Dual-X (for the largest solid angle and high-throughput STEM EDS mapping).

The Super-X detector system provides a highly collimated solid angle of 0.7 Sr and a Fiori number greater than 4000. Super-X is designed for STEM EDS experiments, where spectral cleanliness and quantification are critical.

The Dual-X detector system provides a solid angle of 1.76 Sr and a Fiori number greater than 2000. Dual-X is designed for high-throughput STEM EDS experiments, such as EDS tomography, or when signal yield is low and fast mapping is critical.

A DyScO3 perovskite system is examined with the Dual-X detectors below. The ultra-high brightness (>>1.0 x 108 A/m2/Sr/V*) of the X-CFEG and the resolving power of the S-CORR probe corrector are used to deliver a probe to the specimen with 150 pA of current and size <80 pm. With these high brightness probe conditions, EDS mapping can be done rapidly with high sampling and a high signal to noise ratio, resulting in, for the first time, sub-Angstrom spatial information in a single elemental, raw, and unfiltered EDS map. A fast Fourier transform of the Sc map shows up to 90 pm resolution. Additionally, the built-in EDS quantification engine in the Velox Software makes STEM EDS on Spectra 300 (S)TEM fast, easy and quantifiable.

DyScO₃ specimen investigated with the powerful combination of ultra-high brightness X-CFEG, S-CORR and the large solid angle (1.76 Sr) of the Dual-X detectors, resulting in high signal-to-noise ratio, atomic resolution (up to 90 pm), unfiltered EDS maps (Sample courtesy Professor L.F. Kourkoutis, Cornell University).

When the Spectra 300 (S)TEM is equipped with an X-FEG Mono it is optimized for high-throughput EELS elemental mapping and for probing the fine structure of core-loss edges, extracting sensitive chemical information. The energy resolution of an X-FEG Mono can be tuned between <0.2 eV and 1 eV.

Super X vs Dual X vs Ultra X

The terms "Ultra X," "Dual X," and "Super X" are referring to specific modes or capabilities related to energy-dispersive X-ray spectroscopy (EDX) in electron microscopy. While the specific details may vary depending on the manufacturer and instrument, here is a general overview:

Ultra X: Ultra X is described as the most sensitive EDX available in the text (300kV accelerating voltage). Only available on Spectra. It suggests that this mode or feature provides enhanced detection capabilities for X-ray spectroscopy. Ultra X is typically designed to offer higher sensitivity and improved signal-to-noise ratio, allowing for more accurate and precise elemental analysis.
Dual X: Dual X likely refers to a dual-energy EDX system. Dual X is available in both Talos 200 and Spectra 200 systems (200kV accelerating voltage). Dual-energy EDX involves acquiring X-ray spectra at two different energy levels simultaneously or sequentially. This technique can provide enhanced identification and discrimination of elements, particularly for samples with overlapping X-ray peaks or complex compositions. Dual X is capable of capturing X-ray spectra from multiple energy levels, enabling more comprehensive elemental analysis.
Super X: Super X is available in both Talos and Spectra systems (200kV accelerating voltage). While the exact details are not provided in the text, it likely refers to an advanced EDX system that offers superior performance in terms of sensitivity, energy resolution, or other analytical capabilities. Super X is designed to provide high-quality X-ray spectroscopy and elemental analysis.

Lorentz microscopy

To study pristine magnetic structure, samples may need to be analyzed in so-called field free mode. The Spectra Ultra (S)TEM can be configured to work with virtually zero magnetic field across the entire visible sample volume. Experiments can be performed both in TEM and STEM modes: in particular, the latter enables DPC or ptychography studies with resolution equal to approximately 2 nm (Conventional Lorentz S/TEM) or <0.5 nm (Cs Corrected Lorentz S/TEM). It also allows you to perform in situ magnetization of the samples by varying the excitation of the objective lens in order to retrieve additional information on the behavior of the structures in real operating conditions.

Lorentz ptychograph of FeGe thin film acquired with a residual field of 130 mT, courtesy of Prof. D. Muller, Cornell University. Scale bar equals 50 nm.

STEM HAADF, iDPC and DPC images of a Co film acquired in Zero field. Courtesy of M. Waaijer and R. Egoavil, Thermo Fisher Scientific.

Velox Software

Thermo Scientific Velox Software is a cutting-edge transmission electron microscopy software that offers comprehensive experimental control. It facilitates access to scanning transmission electron microscope (STEM and TEM) optics and detectors, enhancing the reproducibility, yield, and support for quantitative STEM and TEM material analysis.

Velox Software stands out with its integrated ergonomic user interface and ease of use, providing ultimate quality in imaging and compositional mapping. Integrated SmartCam brings efficient setup of experiments. Additionally, it has an interactive detector layout interface for optimal experimental control and documentation on multidetector tools. Velox supports high-contrast atomic imaging of light and heavy elements, and enables flexible STEM and TEM movie recording for dynamic studies.

Enhancing EELS and EDS Spectroscopy with Thermo Scientific Velox Software

The software is equipped with unique packages for EELS spectroscopy and energy-dispersive X-ray spectroscopy (EDS), combined with Thermo Scientific Ultra-X Detector. This robust mapping engine integrates multiple techniques optimized for transmission electron microscopy, ensuring the acquisition of best-in-class spectrum images with high yield. The software also provides live feedback during acquisition and fast post-processing of EELS and EDS data.

Overall, Thermo Scientific Velox Software is a powerful tool that offers superior control, quality, and versatility in transmission electron microscopy, making it an essential part of the scientific research ecosystem.