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This year's theme will be Recent Advances in Electron and Ion Microscopy.
Last updated: July 23, 2019, 3:27 pm
Our spatial world is inherently three-dimensional and materials characterization experts have progressively been driven to understand three-dimensional structure-property relationships across volumes from bulk down to the nanoscale. Material characterization as a field of science also has a very symbiotic relationship with the technology it is largely responsible for driving forward. The techniques and methods for materials analysis evolve with the pace of the science and technology embedded in the increasing complex analytical tools, which in turn, are applied to enable our understanding and develop newer technology. This presentation will focus on three-dimensional characterization involving the application of electron microscopy, electron spectroscopy, ion spectroscopy and optical spectroscopy over various length scales. We will describe methods and show examples of surface reconstructions with an SEM, volume reconstructions with a FIB-SEM and the hybrid applications involving electrons, ions and photons to derive three-dimensional rich data sets from >1 cm3 to <1 nm3. The computational resources required analyzing and process "big data" - as well as just retrieval and storage - is a non-trivial aspect of the process. We will also touch upon concepts and trends which, in the author’s personal opinion, are pointing the way to an even higher level of synergy between advanced materials characterization, computational microscopy and computational micro-spectroscopy. We will discuss problems driving this need and the vanguards of the science and technology leading this research. Computational methods cover a wide array including point spread function deconvolution, compressed sensing and forward modeling. We are coming into an age where computational materials analysis based upon data, information and decisions exchanged between intelligent systems will enable materials characterization in a manner well beyond the comparatively simple repetitive code which drives 3D materials analysis today.
Choosing the correct microscope high tension, or accelerating voltage, is an important experimental consideration for TEM imaging and microanalysis. Higher accelerating voltages naturally lead to better spatial resolution for imaging, but will also lead to accelerated specimen damage. For microanalysis, lower accelerating voltages mean more beam spreading and worse spatial resolution, but also enhanced microanalysis cross sections for EDS and EELS. A new generation of aberration corrected microscopes gives the user the flexibility to operate over a wide range of high tension with unprecedented imaging and chemical spatial resolution. This means that on the same instrument, the voltage can be dialed in for a given experiment and readily changed as different experimental needs arise. The addition of a cold field emission gun, advanced aberration correctors and advanced detectors only enhances operation at both high and low voltages, further adding to instrument flexibility.
With the nearly universal acceptance of the Scanning Transmission Electron Microscope (STEM) as a primary imaging and analysis tool, the simplicity of the technique is often overlooked. In the dedicated STEM, one typically needs to be concerned only with the illumination semi-angle and the strength of the single projection lens to carry out imaging experiments. In this talk, these simple concepts will be used to explain image contrast optimization for the bright field, dark field, and secondary electron imaging modes in the STEM.
Chemical analysis and imaging in transmission mode provides data on the volume of a sample and is the typical realm of the high kV microscopes. The latest instruments allow to acquire the data from the transmitted beam as well as the surface data, down to atomic resolution resulting in improved capabilities for investigating nano-materials.
Quantitative Analysis is an integral part of EDS analysis which has numerous fundamental requirements. X-ray mapping is also a standard application of EDS data collection. There are certain considerations when combining both individually valuable techniques. The result of the combined functions is a full characterization revealing more about a sample than with each individual function. In this presentation, we'll review the essential requirements for quantitative analysis and for x-ray mapping, and then explore methods for generating the most accurate, high quality data. This will include analyses where those requirements are in conflict, such as finding the right amount of time to get high statistics for quant accuracy, but still maintaining a high resolution image.
Conventional EDS detectors in the SEM or TEM are hampered by their active area and distance from the sample, a fact that is made worse when the sample cannot tolerate high KV or high probe current e-beam conditions. Novel detector designs can dramatically increase the EDS solid angle and allow researchers to use microscope settings appropriate for imaging fragile or nano-scale features while still acquiring x-ray data at rates that are fast and allow the full range of analytical tools to be used.
ZEISS ORION NanoFab is a unique focused ion beam instrument capable of generating helium, neon, and gallium ion beams. Based on the Gas Field Ion Source (GFIS) technology, the instrument creates an extremely collimated, highly coherent ion beam that can be used for highest resolution imaging with probe sizes of less than 0.5nm and for precise nanofabrication down to a dimension of about 5nm. This allows for the fabrication of structures such as plasmonic devices and nanopores, patterning of 2D materials, or ion beam lithography with feature sizes well below of what can be achieved with conventional gallium FIBs. The use of inert ion species also eliminates metallic contamination during the milling process and enables deposition of ultra-fine high quality metal or insulator lines. The addition of a gallium focused ion beam column allows for large volume material removal at high speeds. In this presentation, we will give an overview of the fascinating applications that are made possible with helium and neon ion beams. In addition, we will show some of ORION NanoFabs new features and capabilities such as TEM sample preparation, 3D nanotomography, and Secondary Ion Mass Spectrometry (SIMS).
The Hitachi NX9000 orthogonal FIB-SEM system is advancing the field of material processing by lifting the constraints often encountered by V-shaped FIB-SEM instruments. An ever increasing need for three-dimensional signal capture and reconstruction often demand a large amount of time for post processing. Several types of application examples are presented demonstrating an easier workflow illustrating why an orthogonal FIB-SEM system is advantageous for providing a level of precise and accurate measurement with a high degree of repeatability.
Electron Backscatter Diffraction (EBSD), in the past 25 years, has gone from an esoteric technique to one that is routine and essential in many areas of study. The hardware and software have also advanced to the point where basic data collection and visualization have been expanded into the third dimension and the nanometer scale. This talk reviews some of those advances, including transmission Kikuchi diffraction (TKD), 3D data analysis and high resolution dynamical simulation of EBSD patterns.
Electron Backscatter Diffraction (EBSD) and automated orientation mapping (OIM) has become a well-established microstructural characterization tool for materials and earth sciences. As this technique has developed over the past two decades, the acquisition speed has improved by over three orders of magnitude, from under 1 point per second in 1996 to over 1,400 points per second in 2016. This performance has been obtained through improvements in camera and computer hardware as well as software optimization. The improvements in data collection speed are useful for both 2D and 3D EBSD experiments.
There are additional benefits that are available using this type of detector. One application is using the EBSD detector system as an electron imaging detection system. This approach allows for the simultaneous collection of multiple images with contrasts determined by the geometrical position of the EBSD phosphor screen relative to the sample. With this approach images with orientation, atomic number, and topographical contrast information can be obtained and easily correlated with traditional orientation and phase information collected during EBSD mapping. Another application is using a spatial averaging approach to reduce the noise in collected EBSD patterns to improve indexing performance. This approach allows users to operate the camera at faster frame rates and at lower beam currents than traditionally possible. In this presentation, both of these applications will be presented and applied to an array of different materials of interest to both materials and geological scientists.
STEM diffraction imaging is an accurate analysis technique to acquire information on material structure, strain, and texture. In this technique either a parallel or a convergent electron beam with a probe size as small as 0.2 nm is passed through the specimen to generate diffraction patterns. These patterns can be used to characterize individual nano particles, defects and interfaces and allow accurate measurements of strain and crystal orientation. 4D-STEM diffraction data is collected by scanning the electron probe on the specimen and collecting a diffraction pattern at each pixel of the scan. One of the main drawbacks with this technique has been the limitation of the data collection speed. Conventional CCD cameras are limited to about 30 frames per second (fps), which limits the number of diffraction patterns that can be collected in a reasonable amount of time. This is even more disadvantageous in cases where specimens are beam sensitive and/or drift. In such cases by the time data collection is complete, the sample has experienced radiation damaged or moved out of the field of view. In this talk, 4D-STEM datasets collected with both high speed CMOS and conventional CCD cameras will be compared, to show how newly developed CMOS systems with superior DQE and speed can benefit such experiments.
The world of transmission electron microscopy is rapid evolving in conjunction with advances in modern day technology. The Hitachi HT7700 pushes boundaries once not possible and redefines the 120kV class of TEMs whereby it stands apart as the only all digital microscope utilizing the latest technology to challenge traditional limitations and restrictions. Additionally, Ionic Liquids have been taking the field of electron microscopy by storm in recent years and with the addition of Hitachi HILEM IL1000 ionic liquid, new techniques for specimen processing are revolutionizing not only the field SEM but also that of TEM.
Hitachi's new AeroSurf 1500 Tabletop Atmospheric Scanning Electron Microscope (ASEM) revolutionizes SEM observation of wet samples in atmospheric pressures while also offering viewing under a traditional vacuum environment. It can accommodate specimens which are normally difficult to observe in their natural state, such as high-moisture samples, soft materials, and bio-samples. With a conventional SEM, these types of samples require some amounts of sample preparation, when viewing in a SEM is desired. The sample chamber and the SEM column are separated via membrane which allows the electron beam but not the vacuum, to reach the sample chamber. Thus the electron beam can be used to view a sample even while the sample is not under vacuum. This eliminates the need for the damaging, time-consuming sample preparation of high-moisture samples. The membrane has no contact with the sample, so the observed area can be shifted and sample surface can also be observed as if it were under traditional SEM conditions. This novel feature is also useful for timed observation of the changes that occur in high-moisture samples during a drying process, something that has been difficult with a conventional SEM.
Focused ion beam (FIB) milling is a widely used technique for preparing transmission electron microscopy (TEM) specimens. The challenge is to create specimens that are electron transparent and are free from artifacts. Fischione Instruments' PicoMill® TEM specimen preparation system is the ideal complement to FIB technology; it produces optimal specimen quality while enhancing the overall specimen preparation throughput by moving final thinning offline.
The quality of data produced using a scanning electron microscope is highly dependent upon the quality of the specimen surface following sample preparation. Mechanically prepared surfaces often contain artifacts, contaminants, or induce physical deformation along the prepared surface, which can cause key features or fine structures to be obscured or concealed. Broad ion beam (BIB) milling using the Hitachi IM4000Plus provides a contactless method to prepare sample surfaces as well as generate cross-sections, thereby reducing the number of steps employed during preparation or enhancing the surface-quality produced from existing techniques.
