The Thermo Fisher Scientific Spectra200, a state-of-the-art (S)TEM installed at EPFL-Valais, facilitates high-throughput, aberration-corrected scanning transmission electron microscopy of materials for a wide array of applications.
| (S)TEM |
Probe corrected Energy spread: 0.4 eV Information limit: 110 pm STEM resolution: 60 pm (136 pm @ 30 kV) |
| Source |
X-CFEG: Ultra-high-brightness C-FEG with energy resolution of <0.4 eV Flexible high-tension range from 30 – 200 kV |
| Analytics |
Super-X EDS, integrated software Analytics for live peak identification and background fitting during EDS acquisition Symmetric EDS detector design allows for combined tomographic EDS |
| Detectors |
HAADF detector On-axis solid state, 8 segmented BF and ADF detectors (16 segments in total) Thermo Scientific Ceta 16M Camera (with speed enhancement) |
The Spectra 200 (S)TEM is 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, and can be operated from 30 – 200 kV. This provides high-resolution STEM imaging with high probe currents for high-throughput, fast acquisition STEM analytics. With the powerful combination of X-CFEG and S-CORR probe aberration corrector, sub-Angstrom STEM imaging 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. 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.
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 that 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.
The combination of enhanced mechanical stability, the latest 5th order S-CORR probe aberration correction and the X-CFEG, gives the Spectra 200 (S)TEM high-resolution, high-contrast STEM imaging capability for all accelerating voltages. Additionally, Spectra 200 (S)TEM retains the wide gap S-TWIN objective lens as standard from the Themis product line, to ensure customers have a pole gap with “room to do more” without compromising on spatial resolution. In the images below, 48 pm resolution is shown on a wide gap S-TWIN Spectra 200 (S)TEM at 200 kV.
Adding to ease of use, the Spectra 200 (S)TEM includes smart software algorithms to quickly, reproducibly and reliably correct up to 4th order aberrations in the STEM probe (Auto S-CORR) and optimize 1st and 2nd order aberrations on any specimen (OptiSTEM+). Auto S-CORR can therefore be used on a weekly basis to maintain high-order aberrations and OptiSTEM+ can be used daily to optimize image quality without the need of a standard specimen or manual tuning.
The Spectra 200 (S)TEM offers STEM resolution specifications of 60 pm at 200 kV, 96 pm at 60 kV and 125 pm at 30 kV. For a full list of specifications, please refer to the Spectra 200 (S)TEM datasheet.
STEM imaging on the Spectra 200 (S)TEM has been re-imagined 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 entire signal 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.
The Spectra 200 (S)TEM is configured with a Thermo Scientific Ceta Camera with speed enhancement to collect 4D STEM data sets. The Ceta Camera with speed enhancement offers an alternative for 4D STEM applications where a greater number of pixels is required and when EDX 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 Spectra 200 (S)TEM has been configured to be a STEM analytics powerhouse. The extreme brightness and low energy spread of the X-CFEG, the latest generation, 5th order S-CORR probe corrector, the wide gap (X-TWIN) pole piece with a portfolio of large solid angle and symmetric EDS detectors and the built-in EDX quantification engine in Thermo Scientific Velox Software makes STEM EDX on Spectra 200 (S)TEM fast, easy and quantifiable.
The Thermo Scientific EDX detector portfolio provides a choice of detector geometries to suit your experimental requirements and optimize EDX results. Both configurations have a symmetric design (see below), producing quantifiable data. Note that holder shadowing as a function of tilt is compensated in both detector configurations via built-in Velox Software functionality.
The Super-X detector system provides a highly collimated solid angle of 0.7 Sr and a Fiori number greater than 4000. It is designed for STEM EDX experiments where spectral cleanliness and quantification are critical.
Available holders are:
- Protochips Fusion Select
- Protochips Posiedon
- Protochips Atmosphere