Advanced Analytical Scanning Transmission Electron Microscopy (STEM), and Future Directions
There has been increasing demand for so-called ‘workhorse’-type transmission electron microscopes as the technologies and techniques in (scanning) transmission electron microscopy (S/TEM) have evolved. Researchers and engineers from diverse industries depend on the unparalleled spatial resolution of S/TEM imaging for key structural insight into novel nanomaterials and devices, spurring recent developments of more flexible, reliable instrumentation.
In this webinar, learn about the key features that have developed to facilitate accurate, atomic-scale S/TEM imaging for industrial applications. Guest speaker Dr. Patrick Phillips, Assistant TEM Product Manager at JEOL USA, will be exploring hardware and operational strategies to optimize image resolution, clarity, and insight from advanced S/TEM imaging techniques.
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This Webinar Will Answer
- What advancements are incorporated in modern S/TEM instruments?
- What are the current capabilities of a conventional S/TEM outfitted with a cold field-emission gun?
- What new possibilities for analysis are possible with the current state-of-art S/TEM?
- How can non-aberration corrected S/TEM be used to investigate and optimize advanced materials and devices?
- How is the field of S/TEM expected to expand and advance in the coming years?
Aberration Correction Isn’t as Necessary as It Once Was
For decades, only aberration-corrected S/TEM instruments were able to achieve reliable atomic resolution; analysts came to infer that aberration-corrected microscopes – often costing upwards of a million dollars to purchase, let alone maintain – were practically a prerequisite for capturing images at atomic scale.
Today’s tools turn that preconception on its head. Enhancements to cold field-emission sources, large-area silicon drift detectors (SDDs) and increased stabilization in the electron optics of transmission electron microscopes help to ensure top-quality images even in the absence of aberration correction. Find out how these recent technologies coalesce with operational strategies to enable new kinds of analysis on advanced materials and devices.
Q&A Session
What is the typical thickness of a STEM sample for low-voltage imaging?
Sample thickness can be highly dependent on the constituent elements, as well as the imaging voltage in question. For example, most 30 kV STEM is performed on 2D materials, which are by nature very thin. For something like a semiconductor sample, I would estimate 10-20nm is an appropriate thickness for 30 kV STEM. For a slightly higher voltage, like 80 kV, I would estimate you could get away with a sample on the order of 50-80nm.
What software is being used for the segmented STEM?
JEOL Software, within the STEM imaging operation.
How long would it take to obtain a 3D tomography image?
This is highly dependent on the acquisition parameters (e.g., tilt range, number of images within that tilt range, size of the ROI, etc.).
What software is used to do the reconstruction of STEM-EDS tomography? If it is available for use on other systems, how can users access this software?
The software is called TEMography (https://temography.com/en/) by System in Frontier, Inc.
Sometimes EELS analysis fails to detect a lightweight element, such as Boron. Can you share any suggestions for improving accuracy when analyzing lightweight elements with EELS?
Sample preparation could be critical here, especially to ensure the sample is thin enough.
Why is it that we can sometimes see Si signal in samples without any Si content, when these samples are loaded on a lacy Carbon-coated, Copper, or Gold TEM grid? Is there any artifact source related to the microscope compartments?
Not that I can think of. Please feel free to email pphillips@jeol.com for additional discussion if desired.
How could a user apply OBF to current JEOL 200CF and DM 3.5 systems?
To enable OBF, a segmented STEM detector and the OBF software would need to be installed. These items can be retrofit to many existing JEOL instruments.
Why is contrast inversion performed during OBF imaging?
Please see the following paper: https://doi.org/10.1016/j.ultramic.2020.113133
Is it possible to make these measurements faster? How can you optimize for speed when doing tomography or OBF experiments?
It is possible to speed up the imaging by using a faster scan or limiting your ROI. It will be a trade-off between time and quality of data output. Having said that, JEOL (as well as many camera companies) continue to improve detector technology/speed.
For 3D EDS, it’s understood that you need good software and that it helps to have a large-area EDS detector (more than 70 mm or more). What is the detector and software configuration on the JEOL microscope?
The F200 used for these experiments has two 100mm2 EDS detectors and TEMography software for reconstruction (https://temography.com/en/)
How reliable is EDS data is for quantitative analytical applications, where we want to understand the chemical composition of the sample?
EDS in the TEM is notoriously tricky for quantitative work. There are many variables which must be accounted for, which are quite difficult to accurately characterize. For example, sample characteristics/shape, detector metrics, etc. Having said that, JEOL strives to use the best possible quantification routines for EDS.
How would you recommend handling sample drift during atomic-resolution EDS mapping?
JEOL has recently introduced “Lossless Drift Correction”, which is essentially a live-image drift correction routine. It works well for atomic-resolution EDS mapping.
Can you provide an example of ELNES structures for a higher energy range (such as Cu, Co, Ni)
Many examples of this type currently exist in published literature.