Ideal optimization of S/TEM imaging requires EDX and EELS to acquire different signals at different acceleration voltages. The conditions may differ from one sample to another. However, it is widely accepted that:
- The best imaging is executed at the highest possible accelerating voltage, and crossing it leads to visible damage.
- EDX, particularly when mapping, benefits from lower voltages with elevated ionization cross-sections, which results in better signal-to-noise ratio maps for a specified total dose.
- EELS performs better at high voltages to inhibit multiple scattering, which affects the EELS signal with an increase in sample thickness.
However, so far, it has not been possible to acquire different accelerating voltages on the same sample without the loss of the region of interest — all in a single microscopy session.
Visualize a Thermo Scientific Spectra 300 S/TEM:
- That can really work at different voltages (between 30 and 300 kV, for which alignments were bought) in a single microscopy session
- Where a change from one accelerating voltage to another requires about 5 minutes
- That can house a radically different EDX concept with a 4.45 srad solid angle (4.04 srad solid angle with an analytical double tilt holder)
The new Spectra Ultra S/TEM offers adjustable accelerating voltage, quite similar to how the probe current is adjustable, and the massive Ultra-X EDX system allows chemical characterization of materials that are highly beam-sensitive for traditional EDX analysis.
The Spectra Ultra aberration-corrected S/TEM provides best-in-class characterization capabilities for semiconductor and materials science applications at the highest resolution on an extensive range of samples.
Built on an Ultra-Stable Foundation
The Spectra Ultra S/TEM comes on a platform created to deliver an unmatched level of mechanical stability and quality through (optional) active and passive vibration isolation.
Similar to the Thermo Scientific Spectra 200 S/TEM and Spectra 300 S/TEM, the Spectra Ultra S/TEM system is accommodated in a completely redesigned enclosure with an integrated on-screen display for convenient loading and removal specimen.
Complete modularity and upgradeability can be offered, for the first time, between single-corrected and uncorrected configurations with variable heights. This ensures maximum flexibility for various room configurations.
Key Features
- In situ capabilities of the Spectra Ultra S/TEM
- Unprecedented sensitivity with the Panther STEM detection system
- Delivers advanced STEM imaging capabilities
- Lowest dose of STEM/EDX to characterize more materials
- Quickest time to acquire optimized results from more materials
- High-energy resolution and high brightness sources
- Delivers STEM imaging performance of highest resolution
Specifications
Source: Thermo Fisher Scientific – Electron Microscopy Solutions
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Uncorrected
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- Energy spread: 0.2–0.3 eV
- Information limit: <100 pm
- STEM resolution: <136 pm
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Probe corrected
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- Energy spread: 0.2–0.3 eV
- Information limit: <100 pm
- STEM resolution: <50 pm (125 pm @ 30 kV)
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Probe+Image Corrected X-FEG/Mono
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- Energy spread: 0.2–0.3 eV
- Information limit: <60 pm
- STEM resolution: <50 pm at 300 kV with >30 pA of probe current
STEM resolution: <125 pm at 30 kV with >20 pA of probe current
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Probe+Image Corrected X-FEG/UltiMono
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- Energy spread: 0.05 eV (0.025 eV @ 60 kV)
- Information limit: <60 pm
- STEM resolution: <50 pm at 300 kV >30 pA of probe current
STEM resolution: <125 pm at 30 kV with >20 pA of probe current
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Probe+Image Corrected X-CFEG
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- Energy spread: 0.4 eV
- Information limit: <70 pm
- STEM resolution: <50 pm (<136 pm @ 30 kV) with >100 pA of probe current
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Source
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- X-FEG Mono: High-brightness Schottky field emitter gun and monochromator with a tunable energy resolution range between 1 eV and <0.2 eV
- X-FEG UltiMono: High-brightness Schottky field emitter gun with ultra-stable monochromator and accelerating voltage with a tunable energy resolution range between 1 eV and <0.05 eV (<0.025 eV @ 60 kV)
- X-CFEG: Ultra-high brightness with an intrinsic energy resolution of <0.4 eV with 14 nA of total beam current and <0.3 eV with 2 nA of total beam current
- Flexible high-tension range from 30 – 300 kV
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