For in-situ analysis, the capability to capture data at high speed and dose efficiency is critical for capturing data over the desired range of in-situ conditions.Single electron counting direct detection cameras are the ideal detector choice for in-situ (scanning) transmission electron microscopy due to their inherently high detective quantum efficiency (DQE) and high frame rates [1].Furthermore, the rejection of read noise by such detectors, allows collection of a large number of in-situ frames, which can then be summed together as needed to balance signal-to-noise against temporal resolution during data analysis.A prototype method for in-situ spectrum image (SI) acquisition was recently demonstrated using a current generation EELS spectrometer (GIF Continuum) and Gatan DigitalMicrograph [2].Copper (II) oxide was reduced in-situ by heating in a MEMS based heating holder (Wildfire, DENSSolutions).ELNES mapping of Cu L 2,3 spectra performed both live and postacquisition showed a trend of decreasing Cu oxidation state from majority Cu(II) to Cu(0) at the end of the experiment alongside spontaneous changes in CuO particle morphology at specific temperatures.Limitations in the prototype approach were also observed.Non-zero dead time between successive spectrum image passes was found to account for a large fraction of total acquisition time if the time to acquire each SI pass was short.A requirement to keep the full SI time series in system memory limited the temperature range and increment that could be used.Finally, a lack of native software features for processing SI time series data made processing times impractical for larger datasets including multiple ionization edges.Here we demonstrate recent advances in in-situ spectrum imaging capability that have been made possible by a flexible next generation scan control system (Digiscan3) and an expansion of the in-situ software features in DigitalMicrograph.Continuous multiple pass scanning can now be performed, allowing successive spectrum image passes to be acquired with zero dead time between scans.Hardware synchronized sub-pixel scanning can also be performed, giving an increase in scan speed of up to 90x that of the previous generation scan system.These features combined, dramatically increase the time resolution at which in-situ spectrum image acquisition can be performed.New software features include full support of all SI processing functions for in-situ, allowing rapid data analysis.Finally, all SI data acquired is now streamed to disk by the software, drastically increasing the size of datasets that may be captured.In-situ heating has been performed on a variety of materials including: metal nanoparticles, and oxide nanopowders such as Fe 2 O 3 .H 2 O as shown in figure 1. Heating cycles were performed both with and without holder synchronization and control.The benefits of both approaches are discussed.To explore a more complex experimental setup, the ferroic phase changes of improper ferroelectric Cu, Cl, and Fe, I based boracites were investigated by in-situ heating and cryogenic cooling.Changes in the fine structure of the Cu, and Fe with corresponding O were analyzed at the ferroelectric domain walls during temperature induced phases changes and when moved by an applied bias.As the transition metal coordination chemistry dictates the resulting functionality (i.e.charge or magnetism) it is essential to be able to analyse the EELS fine structure during domain wall dynamics.

Journal Article Autonomous Multimodal Spectrum Imaging for High Throughput Data Acquisition Get access Liam Spillane, Liam Spillane Gatan Inc., Pleasanton, CA, United States Corresponding author: liam.spillane@ametek.com Search for other works by this author on: Oxford Academic Google Scholar Bernhard Schaffer, Bernhard Schaffer Gatan Inc., Pleasanton, CA, United States Search for other works by this author on: Oxford Academic Google Scholar Paul J Thomas, Paul J Thomas Gatan Inc., Pleasanton, CA, United States Search for other works by this author on: Oxford Academic Google Scholar Michael Zachman Michael Zachman Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, TN, United States Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 29, Issue Supplement_1, 1 August 2023, Pages 1902–1903, https://doi.org/10.1093/micmic/ozad067.982 Published: 22 July 2023

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Electron energy-loss spectroscopy (EELS) performed in the scanning transmission electron microscope (STEM) is a powerful technique for probing local electronic structure at high spatial resolution via the spectrum imaging (SI) paradigm. For in-situ analysis, the capability to capture spectral data at both high speed and high dose efficiency is critical. Traditional CCD based detectors used for EELS are capable of high spectral rates but give inherently low collection efficiency at high speed due to fixed readout dead time. Spectral quality is further compromised by the need to perform high levels of asymmetric binning to achieve the maximum frame rate. The current generation of CMOS based EELS detectors do not rely on binning for performance gains and utilize rolling shutter readout. With the use of fast electrostatic deflectors, these detectors can achieve nearly 100% live time readout at high spectral rates ( > 8 kHz) giving high dose efficiency. Incorporating such a detector into an optimized STEM EELS acquisition system gives a highly efficient platform for in-situ STEM EELS experiments.

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Journal Article Simultaneous High-Speed DualEELS and EDS acquisition at atomic level across the LaFeO3 / SrTiO3 interface Get access P Longo, P Longo Gatan Inc. 5794 W Las Positas Blvd, Pleasanton, CA, 94588, USA Search for other works by this author on: Oxford Academic Google Scholar T Topuria, T Topuria IBM Research Division, Almaden Research Center, San Jose, CA, 95120, USA Search for other works by this author on: Oxford Academic Google Scholar P Rice, P Rice IBM Research Division, Almaden Research Center, San Jose, CA, 95120, USA Search for other works by this author on: Oxford Academic Google Scholar A Aitouchen, A Aitouchen Gatan Inc. 5794 W Las Positas Blvd, Pleasanton, CA, 94588, USA Search for other works by this author on: Oxford Academic Google Scholar PJ Thomas, PJ Thomas Gatan Inc. 5794 W Las Positas Blvd, Pleasanton, CA, 94588, USA Search for other works by this author on: Oxford Academic Google Scholar RD Twesten RD Twesten Gatan Inc. 5794 W Las Positas Blvd, Pleasanton, CA, 94588, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 21, Issue S3, 1 August 2015, Pages 1857–1858, https://doi.org/10.1017/S1431927615010065 Published: 23 September 2015

Journal Article Simultaneous High-Speed DualEELS and EDS Acquisition at Atomic Level Get access P Longo, P Longo Gatan Inc. 5794 W Las Positas Blvd, Pleasanton, CA, 94588, USA Search for other works by this author on: Oxford Academic Google Scholar T Topuria, T Topuria IBM Research Division, Almaden Research Center, San Jose, CA, 95120, USA Search for other works by this author on: Oxford Academic Google Scholar P Rice, P Rice IBM Research Division, Almaden Research Center, San Jose, CA, 95120, USA Search for other works by this author on: Oxford Academic Google Scholar A Aitouchen, A Aitouchen Gatan Inc. 5794 W Las Positas Blvd, Pleasanton, CA, 94588, USA Search for other works by this author on: Oxford Academic Google Scholar PJ Thomas, PJ Thomas Gatan Inc. 5794 W Las Positas Blvd, Pleasanton, CA, 94588, USA Search for other works by this author on: Oxford Academic Google Scholar RD Twesten RD Twesten Gatan Inc. 5794 W Las Positas Blvd, Pleasanton, CA, 94588, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 20, Issue S3, 1 August 2014, Pages 128–129, https://doi.org/10.1017/S1431927614002360 Published: 27 August 2014

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

N-type III-V materials are one of the potential candidates to replace Si MOSFET technology. In particular n-type GaAs shows carrier mobility 5 times higher than that of Si [1]. Until recently, the realization of GaAs based MOSFET devices has been limited by the difficulties of making a good dielectric oxide layer in terms of leakage current and unpinned Fermi level. However, it has been shown that the evaporation of O2 onto a GaAs surface leads to the formation of a pinned Fermi level at the interface. The O2 initially displaces surface As atoms and then bonds to the Ga atoms in the second layer. When two O atoms are bonded to a central Ga atom, they withdraw charge from the second Ga atom determining the state formation within the gap. The presence of this central atom between two O atoms is the main reason why the Fermi level results to be pinned by direct oxidation. On the other hand, when Ga2O is absorbed onto the GaAs surface, it appears to insert into As dimer pairs. Once it has been fully absorbed, a surface reconstruction occurs leaving the surface with 2x2 periodicity. This new surface appears to passivate the surface and change the charge on the initial As surface atoms towards more bulk like value. The new Ga atoms in the chemisorbed Ga2O layer as well as the second layer Ga atoms in the substrate have no states in the band gap. The presence of this Ga2O monolayer bonded to the GaAs surface determines the Fermi level to be unpinned. Deposition of an amorphous GdGaO layer is needed in order to keep the leakage current to a low value [2]. Thus, the performance of the entire transistor is largely influenced by the morphology and chemistry across the interface. Scanning Transmission Electron Microscopy ((S)TEM) related techniques are particularly suited to investigate the structure and the chemistry of this interface. In particular the combination of electron energy loss spectroscopy (EELS) and STEM enables spectrum imaging (SI) which is the acquisition of one or more spectra at each point of the scanned image. With the development of aberration corrected microscopes, EELS SI is now routinely used to study the chemistry across interfaces at atomic resolution. However when the sample is electron beam sensitive, atomic resolution level analysis becomes more challenging unless fast spectrometers are used. This is the case of the GaAs/Ga2O3 interface where the amorphous oxide layer tends to crystalize under the electron beam. The GIF Quantum® [3] with its spectral rate of 1000 spectra per second allows the acquisition of atomic EELS maps at a speed fast enough that beam damage is avoided. In addition the lens system present in the GIF Quantum® with the capability to correct the aberration up to the 5th order, leads to the possibility to use large collection angles allowing more signal to enter the spectrometer whilst maintaining the energy resolution.

With advancements in aberration correction, the spatial resolution of scanning transmission electron microscopy (STEM) has been enormously improved. In addition to the reduction of the STEM probe size, a dramatic increase in the STEM probe current has been realized, leading to the routine acquisition of high-resolution elemental and chemical maps using electron energy loss spectrometry (EELS). Using EELS combined with these advanced STEM instruments, atomic-level resolution information can be obtained from various types of materials, revealing the nature of interfaces, elemental distribution, presence of defects, and much more. In addition to simple elemental composition distributions, EELS is capable of delivering information about the chemical bonding, local atomic coordination, oxidation states, band gaps, and chemical phases of a broad range of materials at the fundamental resolution limit of the property being probed. Atomic-level EELS maps of these fundamental material properties can now be obtained with the acquisition time, to a large extent, limited only by the speed of the EELS spectrometer and not by the signal being measured. The availability of fast EELS spectrometers with large angular collection efficiencies has closed the gap between the rate of signal generation in the specimen and the speed at which this signal can be detected. This significantly increases the amount of information that can be acquired using EELS. Using the most recent generation of spectrometers, EELS data can be acquired at well over 1,000 spectra per second with a high-duty cycle. Fifth-order spectral aberration correction in this generation of spectrometers allows the use of the large collection angles needed to match the increased convergence angle that Cs-probe-corrected systems present, improving collection efficiency while maintaining energy resolution. These advances, when taken together, result in a well matched source/detector system capable of recording high-energy EELS edges at atomic resolution at a rate fast enough to limit electron beam damage to the sample.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

We describe a new post-column imaging energy filter for (scanning) transmission electron microscopy from 60 to 300kV operating voltage. The completely redesigned GIF quantum has a gradient magnetic prism, dodecapole optics, a 10-times faster 40Mpixel/sec CCD camera, a 1μs electrostatic shutter, and new user interface, control, and auto-alignment software. An 8 dodecapole lens system, performs full 2nd and 3rd, and partial 4th and 5th order aberration correction. The improved aberration correction has allowed the size of the entrance aperture to be nearly doubled to 9.0mm compared to current generation post-column designs. The electrostatic shutter provides exposure control down to 1μs, extending the exposure time range to over 7 orders of magnitude. Spectroscopy operation has been improved with a larger 2keV field of view at 200kV, and a maximum acquisition rate of 1000 spectra per second. A high-speed DualEELS mode simultaneously acquires core- and low-loss spectra up to 2keV apart. A more intuitive user interface includes new capabilities such as automated exposure control and optimized full spectrum acquisition. The auto-alignment software has been significantly enhanced to use the full flexibility of the dodecapole lens system.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009