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K Shinohara, T Ohigashi, S Toné, M Kado, A Ito
Soft X-ray spectromicroscopy was applied to study the quantitative distribution of DNA and protein in a mammalian chromosome at the spatial resolution of 100 nm. The quantities of DNA and protein were evaluated using 1s-π* transition in the NEXAFS spectra at the nitrogen K absorption edge. DNA was not uniformly distributed in the chromosome and DNA/protein ratio was less than 0.497. The present analysis revealed the clues to identify other molecules that contribute to the absorption spectrum of the sample...
July 5, 2018: Ultramicroscopy
D Mello, M Nacucchi, G Anastasi, M Sacchi, R Ricciari, E Burresi, L Tapfer
In fabrication of microelectronic devices two important steps are often recognized: i) all the processes performed on the wafer in order to build the active part of the devices and, ii) the assembly and packaging processes, typically performed on a chip, in order to fabricate interconnections between active part and exterior. The wafer back side is an active part of power devices and is normally coated with a stack of Ti-Ni-Au or Ti-Ni-Ag layers to ensure the best electrical contact with the frame on which the device is attached prior to the packaging...
June 30, 2018: Ultramicroscopy
Chia-Wei Kuo, Jui-Chao Kuo, Sheng-Chang Wang
This work aims to investigate the influence of intrinsic and extrinsic factors on the physical resolution of the transmission electron backscattered diffraction technique (t-EBSD) in aluminum and silver. Here, we focus on the intrinsic factors, namely, atomic number and thickness of the specimen, and extrinsic set-up factors, which include the electron beam voltage, working distance, and specimen tilt. The working distance and tilt angle, which are selected as 12 mm and 60° for Al and 12 mm and 50° for Ag, respectively, reveal a sharp pattern with high contrast...
June 30, 2018: Ultramicroscopy
R F Egerton, M Watanabe
Fitted with a field emission source, aberration-corrected optics and an energy-dispersive X-ray detector of large solid angle, a modern analytical TEM can generate a current density high enough to chemically identify a single metal atom within a fraction of a second, if the atom remains stationary within the electron probe. However, atom motion will occur if the atomic binding energy is too low, the specimen temperature too high, or the electron accelerating voltage above a certain threshold. We discuss such motion in terms of thermal diffusion, beam-induced sputtering and beam-assisted surface migration...
June 28, 2018: Ultramicroscopy
Paweł Janus, Andrzej Sierakowski, Maciej Rudek, Piotr Kunicki, Andrzej Dzierka, Paweł Biczysko, Teodor Gotszalk
In this paper we present design and application of novel piezoresistive scanning thermal microscopy (SThM) probes. The proposed probe integrates a piezoresistive deflection sensor and thermally active, resistive nanosize tip. Manufacturing technology includes standard silicon MEMS/CMOS processing and sophisticated postprocessing using Focus Ion Beam milling. Authors also describe dedicated measurement technique in order to perform quantitative nanoscale thermal probing. Performance of the developed thermal probes is validated by test scans (topography and temperature distribution) of silicon nanoresistors supplied with current...
June 25, 2018: Ultramicroscopy
Takehito Seki, Yuichi Ikuhara, Naoya Shibata
Statistical noise, or shot noise, dominates experimental image quality in scanning transmission electron microscopy because efficiencies of recent detectors are close to ideal. We establish a general framework for the statistical noise taking into account two random processes in the electron incidence and the electron scattering. Using this framework, in terms of signal-to-noise ratio, we evaluate several STEM coherent imaging techniques: annular bright field, enhanced annular bright field, differential phase contrast, and ptychography and show that ptychography is the most efficient imaging for weak phase objects...
June 23, 2018: Ultramicroscopy
He Li, Xianlong Wei, Gongtao Wu, Song Gao, Qing Chen, Lian-Mao Peng
Interlayer electrical transport between two-dimensional atomic crystals can be strongly modulated by the rotational misalignment between them. However, the experimental study on the interlayer electrical transport between rotated two-dimensional atomic crystals with variable rotation angles is challenging. Here, an in-situ scanning electron microscopy method is developed to study the interlayer electrical transport between rotated graphene layers. We employ nanoprobes installed in a scanning electron microscope to function as both "fingers" to induce interlayer rotation of a microfabricated metal-graphite-metal sandwiched island and also electrical probes to measure interlayer electrical resistivity of the rotated graphene layers...
June 19, 2018: Ultramicroscopy
Wiebke Albrecht, Arjen van de Glind, Hideto Yoshida, Yusuke Isozaki, Arnout Imhof, Alfons van Blaaderen, Petra E de Jongh, Krijn P de Jong, Jovana Zečević, Seiji Takeda
In-situ transmission electron microscopy experiments are of great interest to nanoscience and nanotechnology. However, it is known that the electron beam can have a significant impact on the structure of the sample which makes it important to carefully interpret in-situ data. In this work, we studied the thermal stability of CTAB-stabilized gold nanorods under different gaseous environments in an environmental transmission electron microscope and compared the outcome to ex-situ heating experiments. We observed a remarkable influence of the electron beam: While the nanorods were stable under inert conditions when exposed to the electron beam even at 400°C, the same nanorods reshaped at temperatures as low as 100°C under ex-situ conditions...
June 18, 2018: Ultramicroscopy
Y L Tang, Y L Zhu, Y J Wang, X L Ma
Tuning multiple strain and polar states of ferroelectrics by using strain engineering is an essential approach for designing multifunctional electric devices such as multiple state memories. However, integrating multiple strain states is still a challenge, and in addition, revealing such strains and the resultant polar behaviors on the atomic level remains difficult. In this work we prepare PbZr0.52 Ti0.48 O3 /PbTiO3 (PZT/PTO) superlattices on SrRuO3 -buffered SrTiO3 (001) substrates. Aberration-corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) reveals that the superlattice is coherent in both c (out-of-plane polar direction) and a (in-plane polar direction) domains...
June 18, 2018: Ultramicroscopy
A Fraczkiewicz, F Lorut, G Audoit, E Boller, E Capria, P Cloetens, J Da Silva, A Farcy, T Mourier, F Ponthenier, P Bleuet
In microelectronics, recently developed 3D integration offers the possibility to stack the dice or wafers vertically instead of putting their different parts next to one another, in order to save space. As this method becomes of greater interest, the need for 3D imaging techniques becomes higher. We here report a study about different 3D characterization techniques applied to copper pillars, which are used to stack different dice together. Destructive techniques such as FIB/SEM, FIB/FIB, and PFIB/PFIB slice and view protocols have been assessed, as well as non-destructive ones, such as laboratory-based and synchrotron-based computed tomographies...
June 15, 2018: Ultramicroscopy
Yong Ding, Yu Chen, Ken C Pradel, Weilin Zhang, Meilin Liu, Zhong Lin Wang
Owing to the excellent mixed-ionic and electronic conductivity and fast oxygen kinetics at reduced temperature (<800 °C), double-perovskite oxides such as PrBaCo2 O5+δ exhibit excellent properties as an oxygen electrode for solid oxide fuel cells (SOFCs). Using transmission electron microscopy (TEM), we revealed high-density antiphase domain boundaries (APBs) and 90° domain walls in PrBaCo2 O5+δ grains. Besides the regular lamellar 90° domain walls in {021} planes, irregular fine 90° domains are attached to the curved APBs...
June 15, 2018: Ultramicroscopy
Ping-Luen Ho, Chu-Ping Yu, Qiqi Zhang, Kyung Song, James P Buban, Si-Young Choi, Rafal E Dunin-Borkowski, Joachim Mayer, Nyan-Hwa Tai, Jing Zhu, Lei Jin, Xiaoyan Zhong
Superexchange-based magnetic coupling of the two B-site cations in rock-salt-ordered double perovskite oxides is extremely sensitive to the cation ratio and degree of order. However, as a result of the limited spatial resolution of most magnetic characterization techniques, it is challenging to establish a direct relationship between magnetic properties and structure in these materials, including the effects of elemental segregation and cation disorder. Here, we use electron energy-loss magnetic chiral dichroism together with aberration-corrected electron microscopy and spectroscopy to record magnetic circular dichroism (MCD) spectra at the nm scale, in combination with structural and chemical information at the atomic scale from the very same region...
June 14, 2018: Ultramicroscopy
Yuanyuan Zhu, Colin Ophus, Mychailo B Toloczko, Danny J Edwards
Dislocation imaging using transmission electron microscopy (TEM) has been an invaluable tool for characterizing crystallographic defects in metals. Compared to conventional TEM imaging, diffraction contrast imaging scanning transmission electron microscopy (DCI STEM) with appropriate setting can provide better defect contrast with almost negligible bend contour artifacts, enabling more effective analysis of dislocation structures. Here, we investigated why STEM can suppresses bend contour, and how dislocation contrast behaves along with different STEM imaging parameters...
June 7, 2018: Ultramicroscopy
S Plana-Ruiz, J Portillo, S Estradé, F Peiró, Ute Kolb, S Nicolopoulos
A general method to set illuminating conditions for selectable beam convergence and probe size is presented in this work for Transmission Electron Microscopes (TEM) fitted with µs/pixel fast beam scanning control, (S)TEM, and an annular dark field detector. The case of interest of beam convergence and probe size, which enables diffraction pattern indexation, is then used as a starting point in this work to add 100 Hz precession to the beam while imaging the specimen at a fast rate and keeping the projector system in diffraction mode...
June 6, 2018: Ultramicroscopy
Victor Boureau, Robert McLeod, Benjamin Mayall, David Cooper
In this paper we discuss developments for Lorentz mode or "medium resolution" off-axis electron holography such that it is now routinely possible obtain very high sensitivity phase maps with high spatial resolution whilst maintaining a large field of view. Modifications of the usual Fourier reconstruction procedure have been used to combine series of holograms for sensitivity improvement with a phase-shifting method for doubling the spatial resolution. In the frame of these developments, specific attention is given to the phase standard deviation description and its interaction with the spatial resolution as well as the processing of reference holograms...
June 4, 2018: Ultramicroscopy
J Barthel
The Dr. Probe software for multislice simulations of STEM images is introduced, and reference is given of the applied methods. Major program features available with the graphical user interface version are demonstrated by means of a few examples for bright-field and dark-field STEM imaging as well as simulations of diffraction patterns. The numerical procedure applied for the simulation of thermal-diffuse scattering by the frozen-lattice approach is described in detail. Intensity variations occurring in simulations with atomic-column resolution due to frozen-lattice variations are discussed in the context of atom counting...
June 4, 2018: Ultramicroscopy
B Feng, N R Lugg, A Kumamoto, N Shibata, Y Ikuhara
Atomic-resolution energy dispersive X-ray spectroscopy (EDS) in scanning transmission electron microscopy (STEM) has recently been shown to be a powerful approach to investigate local chemistry of nanoscale structures quantitatively. While most of the studies have been focused on the quantification of the chemical composition in bulk crystals, few were discussed on interfaces. In this study, we theoretically explored the applicability of STEM EDS for the quantification of local chemistry in grain boundaries (GBs), where the electron channeling can be dramatically changed compared with the bulk due to non-periodic atomic arrangement...
June 3, 2018: Ultramicroscopy
Stefan Doering, Andre Wachowiak, Hagen Roetz, Stefan Eckl, Thomas Mikolajick
Scanning spreading resistance microscopy (SSRM) with its high spatial resolution and high dynamic signal range is a powerful tool for two-dimensional characterization of semiconductor dopant areas. However, the application of the method is limited to devices in equilibrium condition, as the investigation of actively operated devices would imply potential differences within the device, whereas SSRM relies on a constant voltage difference between sample surface and probe tip. Furthermore, the standard preparation includes short circuiting of all device components, limiting applications to devices in equilibrium condition...
June 1, 2018: Ultramicroscopy
Alejandro Reyes-Coronado, Carlos Gael Ortíz-Solano, Nerea Zabala, Alberto Rivacoba, Raúl Esquivel-Sirvent
The non-physical effects on the transverse momentum transfer from fast electrons to gold nanoparticles associated to the use of non-causal dielectric functions are studied. A direct test of the causality based on the surface Kramers-Kronig relations is presented. This test is applied to the different dielectric function used to describe gold nanostructures in electron microscopy.
September 2018: Ultramicroscopy
Daniel Knez, Martin Schnedlitz, Maximilian Lasserus, Alexander Schiffmann, Wolfgang E Ernst, Ferdinand Hofer
We present a computational scheme to simulate beam induced dynamics of atoms in surface dominated, metallic systems. Our approach is based on molecular dynamics and Monte Carlo techniques. The model is tested with clusters comprised of either Ni, Ag or Au. We vary their sizes and apply different electron energies and cluster temperatures to elucidate fundamental relations between these experimental parameters and beam induced displacement probabilities. Furthermore, we demonstrate the capability of our code to simulate beam driven dynamics by using Ag and Au clusters as demonstration systems...
September 2018: Ultramicroscopy
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