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The Transmission Electron Microscope

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Nguyễn Gia Hào

Academic year: 2023

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Ying Li, Gaoyang Zhao, Zhibo Kou, Long Jin and Yajing Wang Section 3 Transmission electron microscopy for biological samples 191. The main instruments are the scanning electron microscope, the electron probe X-ray microanalyzer and the analytical transmission electron microscope.

In Situ Transmission Electron Microscopy

It is my hope that this book will help readers to characterize their material more efficiently and give them the opportunity to strengthen their knowledge.

Combined Transmission Electron Microscopy — In situ Measurements of Physical and Mechanical Properties of

Introduction

  • Electrical Property of NCs
  • Structure of NCs
  • Mechanical property of NCs
  • Deformation of NCs

The repetition of elastic and plastic regions is believed to appear in the deformation process of Au NCs. They observed Au ASW in the final stage of the tensile deformation process of Au NCs.

Figure 1. Schematics of atomistic scale devices. (a) NC, (b) ASW, (c) nano-gap structure, and (d) SMJ.
Figure 1. Schematics of atomistic scale devices. (a) NC, (b) ASW, (c) nano-gap structure, and (d) SMJ.

In situ HRTEM

  • Experimental – In situ HRTEM -

When measuring the force acting on a contact, we attached a silicon cantilever used in AFM to one of the sample holders. This time is often shorter than the time resolution of the image acquisition system for TEM (~17 ms / 1 image).

Structure, conductance, and mechanical properties

  • Observation of tensile deformation process
  • Conductance histogram
  • Mechanical properties of Ag NCs during thinning
  • Stable contact with a certain conductance
  • Structures of Ag NCs exhibiting a conductance of 1 G 0

At the same time, we measured the force acting on the contacts to examine the voltage of the NCs. It was also deduced from the estimation of the critical shear stress of NCs that the.

Figure 12. Time variation of HRTEM images in tensile deformation process of Ag NC. Bias voltage of 13 mV is applied.
Figure 12. Time variation of HRTEM images in tensile deformation process of Ag NC. Bias voltage of 13 mV is applied.

Current-voltage characteristics measurement

  • Non-linearity of conductance and scattering of electrons in the Ag NC
  • Metal-specific differences

The current density of the ASW is 2 TA/m2, which is a fifth of that of the 2-atom wide NC. These findings show that the density of states of the ASW differs from that of the NCs.

Figure 21. Time variation in HRTEM images of Ag NCs applying alternative current voltage of 13 mV.[83]
Figure 21. Time variation in HRTEM images of Ag NCs applying alternative current voltage of 13 mV.[83]

Conclusions

This tendency changed when contact transformed into ASW; the nonlinear component became positive. The variation of the nonlinear parameter of Ag NCs with respect to conductivity was similar to that of Au NCs, while it was different from that of Pt NCs.

Acknowledgements

Author details

In Situ TEM system for electric measurements

TEM holders developed for in situ electronic experiments

  • Holders having four or multiple terminals to investigate patterned devices
  • Holder generating in-plane magnetic field
  • TEM/STM holder

The sample (turned upside down) was placed in the center of the holder so that it faced the terminals (Fig. The in-plane field of film devices can be varied by tilting the sample in the remanence field of the TEM objective lens (LowMag mode).

Figure 2. (a) TEM holders for four-terminal electrical measurements. Enlarged image of TEM holder head for (b) JEM2010 and (c) JEM200CX
Figure 2. (a) TEM holders for four-terminal electrical measurements. Enlarged image of TEM holder head for (b) JEM2010 and (c) JEM200CX

Sample preparation method

  • Patterned devices on SiN/Si substrate with observation window
  • Needle-shaped and wedge-shaped probes and substrates
  • Easy method to prepare miniaturized multilayer devices for in situ TEM

At this magnification no carbon particle residues can be identified and we can expect a small fragment of the film on the stylus. There should be areas of needles suitable for in situ TEM somewhere on the substrate, independent of milling time.

Figure 5. (a) Schematic and (b) photograph of TEM/STM holder for JEM200CX. Electrode and sample were placed in‐
Figure 5. (a) Schematic and (b) photograph of TEM/STM holder for JEM200CX. Electrode and sample were placed in‐

Application of developed TEM holders

  • Electromigration
  • Magnetic domains and magnetoresistance of ferromagnetic devices
  • Quantum conductance of metallic nanowires
  • Single electron tunnelling of nanoparticle system
  • Resistance switching of the resistive random access memory

Thus, all regions contributing to the MR effect in Fig. a) MR curve measured by TEM. The Fe particle in this experiment was sandwiched between two large electrodes (i.e., the probe and the substrate).

Figure 8. (a) Schematic of ion-shadow process. (b) SEM of needles formed at Si substrate
Figure 8. (a) Schematic of ion-shadow process. (b) SEM of needles formed at Si substrate

Summary and conclusion

Although the current almost reached Ic at C, the filament did not connect to the Cu TE. When we further increased the negative voltage to −2.6 V, the negative current increased above −300 μA (No. 12), and the filament contracted toward the Cu TE. This region must have had a higher resistance than other areas in the filament and generated Joule heat.

In-situ TEM Study of Dislocation-Interface Interactions

Twin boundaries in Cu

  • Dislocation structure of Σ3 {112} ITB
  • Migration of Σ3 {112} ITBs
  • Dislocation-Σ3 {112} ITBs interactions
  • Dislocation multiplication at coherent twin boundaries

For simplicity, CTB-1 is labeled as “0”, which corresponds to the reference position of the twin plane (Figure 4 a'). There is an additional {111} plane corresponding to the edge component of the dislocation normal to the CTB plane. Accompanying the migration of CTB-2', CTB-3 also migrates up five atomic planes (from -3 to +2), which is the result of the slip of three partial Shockley dislocations of the newly nucleated.

Figure 1. (a) HRTEM image showing atomic structures of both Σ3 {111} CTB and Σ3 {112} ITB
Figure 1. (a) HRTEM image showing atomic structures of both Σ3 {111} CTB and Σ3 {112} ITB

Metallic interphase interfaces

  • Interface structure
  • Dislocation nucleation
  • Confined layer slip
  • Dislocations climb in interfaces
  • Interface shear strength

The bright field TEM micrograph of the cross-sectional view of the 20 nm Cu/Nb multilayers is shown in Figure 7 a. However, the change in adhesion speed occurs at a distance of 1.7 nm (Figure 10b), suggesting that the thermal process starts below this critical distance. Compared with the recorded video, we found that the steady decrease in strength corresponds to shearing of the pillar along the Cu-Nb interface.

Figure 8. (a) HRTEM image shows several stacking faults generated in Cu, with the trailing partials trapped at Cu-Nb interface
Figure 8. (a) HRTEM image shows several stacking faults generated in Cu, with the trailing partials trapped at Cu-Nb interface

Metal/ceramic interfaces

  • Interface structures
  • Deformation mechanism at large individual layer thickness (≥ 50 nm)
  • Deformation mechanism when layer thickness is small (≤ 5 nm)

Morphology change of the first TiN layer during indentation, (a) initial shape of TiN layer before indentation and (b) deformed TiN layer before cracking. The stress field was solved in the TiN layer with a displacement boundary condition determined by the change in morphology from (a) to (b). The tilt boundary between the first TiN layer and the second Al layer, which is related to the accumulation of dislocations in the Al layer and at the interface.

Figure 12. TEM images of the as-deposited films with the individual layer thickness (a) 50 nm and (b) 5 nm.
Figure 12. TEM images of the as-deposited films with the individual layer thickness (a) 50 nm and (b) 5 nm.

Summary

A large plastic deformation was measured according to the change in the first five bilayers under the indenter, the thickness reduction in the first three bilayers from 17.5 nm to 6.3 nm, corresponding to a deformation of -64% (Figure 17d and 17e). The bold dashed lines indicate the Al-TiN interfaces and the thin dashed lines indicate the TiN-Al interfaces. d) and (e) Plastic deformation in first three bilayers corresponds to the thickness reduction from 17.5 nm to 6.3 nm. The bold dashed lines indicate the Al-TiN interfaces and the thin dashed lines indicate the TiN-Al interfaces. d) and (e) Plastic deformation in first three bilayers corresponds to the thickness reduction from 17.5 nm to 6.3 nm.

Shave-Off Profiling for TEM Specimens

Shave-off profiling

  • Shave-off depth profiling
  • Shave-off vector profiling

Shave depth profiling basically originated from the process of shaving with a focused ion beam (FIB) and secondary ion mass spectrometry (SIMS). The specimen volume for shaving depth profiling is almost the same as that prepared for TEM. Shave depth profiling is able to be applied to almost all solid state materials, even for rough structures and heterojunction interfaces.

Experiment

With respect to planing depth profiling, the "depth" only has meaning for the planing directions of the specimen. Shave-off depth profiling has been successfully used to visualize the migration of Cu ions from electrodes to the resin within a point of failure [6]. In this study, the shearing direction was vectorized in the direction from the anode to the cathode.

Results and discussion

The spatial resolution of non-shaving profiling is estimated to be at most 40 nm for multilayers [7]. The critical difference is found by the shaving vector profiling gradient curve between the anodic and cathodic regions. A critical difference was identified by a gradient profile shave profile from anode to cathode.

Figure 3 shows TEM bright-field image and SE image of the same piece picked up from a failed package
Figure 3 shows TEM bright-field image and SE image of the same piece picked up from a failed package

Transmission Electron Microscopy at Nanoscale

We cross-checked the TEM sample images against the shave-free profiling results and introduced a new approach to shave-free vector profiling. In the same work, unshaving profiling can be used to visualize the weak gradient of migrated ions that could not be observed in the TEM image.

Advanced Electron Microscopy Techniques in Nanomaterials Characterization

Aerogels

For the formation ions, dry nitrogen gas (N2) is introduced near the surface of the sample. However, considering that most SE (~90%) have a KE of 10 eV (or even less), which is lower than the ionization energy for N, ionization events by SE should be rare. However, considering that most SE (~90%) have a KE of 10 eV (or even less), which is lower than the ionization energy for N, ionization events by SE should be rare.

Figure 1a is a SEM image of an aluminosilicate aerogel in which charging effects are noticeable.
Figure 1a is a SEM image of an aluminosilicate aerogel in which charging effects are noticeable.

CNT/polymer nanocomposites

However, in the case of electrical properties and single-walled carbon nanotubes (SWCNTs), although the distribution is important, the main control should be focused on a reliable method to identify the abundance of metallic/semiconductor type of nanotubes via chirality [41]. It can be observed that while the SWCNT walls can be resolved in the hole region (free standing), its contrast is lost in the polymer region. From these distances Di the SWCNT diameter and chirality can be estimated.

Figure 4. HRTEM simulations of SWCNT in PE matrix. Reproduced from reference 9 with permission from Wiley.
Figure 4. HRTEM simulations of SWCNT in PE matrix. Reproduced from reference 9 with permission from Wiley.

Graphene/Cu-based nanocomposites

Extensive microscopic analysis showed that the graphene material was decorated with Cu-based nanoparticles of various shapes and sizes. Numerical analysis of neck formation between two nanoparticles was performed to explore the initial steps of coalescence; the data are presented in Figure 8. Molecular dynamics simulations were also performed, taking into account aspects of the nanoparticles that agreed with the experimental results [12].

Porous SnO 2 nanostructures

Likewise, some nanoparticles such as those marked with solid arrows in the figure were oxygen-free. Furthermore, EELS analysis confirmed the SnO2 structure by two methods (see fig. 10): (1) determining the fingerprint of this rutile structure by the presence of unique peaks at 530–. The rutile structure of tin dioxide was also resolved by atomic resolution HAADF imaging as shown in the inset image of Figure 10 .

CNT Yarns

Here, small segments of CNT yarns are exposed to e-beam irradiation in a TEM operating at 200 keV and different doses. To obtain possible explanations for the effects of e-beam irradiation on resistivity, HRTEM analysis of the CNT yarn microstructure was performed. The increase in resistivity at 10 min of e-beam irradiation can be explained by the formation of lattice defects that did not produce enough cross-linked sites to increase conductivity.

Figure 7. SEM images of microstructural evolution of a graphene sheet decorated with Cu nanoparticles in full view, as a function of temperature and time (a)–(f)
Figure 7. SEM images of microstructural evolution of a graphene sheet decorated with Cu nanoparticles in full view, as a function of temperature and time (a)–(f)

WSi 2 /SiGe composites

This must be with the kinetics of defects (production rate, dynamics) at specific locations in the C lattice and agglomeration of point defects leading to larger defects. The inset in Figure 13f is the surface view of the NI SEM image (also taken at 54 degrees), where the radial cracks can be noted. Based on the data obtained in this work, especially on the superior hardness values ​​and decent fracture toughness of the matrix (~45% upper value compared to pure WSi2 phase), we proposed the following to obtain a robust TE WSi2/SiGe material: (1) the segregation problem must be corrected, and (2) the porosity content as well as the mechanical demand must be improved, as well as the mechanical conduction properties. ence ZT).

Figure 13 presents SEM images showing examples of nanoindentation impressions (NI) for WSi 2  phase (13b), matrix (13c), WSi 2 /matrix interface (13d), and Ge rich phase (13e)
Figure 13 presents SEM images showing examples of nanoindentation impressions (NI) for WSi 2 phase (13b), matrix (13c), WSi 2 /matrix interface (13d), and Ge rich phase (13e)

Transmission Electron

Microscopy for the Characterization of Cellulose Nanocrystals

Native cellulose and the production of cellulose nanocrystals

Crystalline and disordered regions alternate along the microfibrils (Figure 1a) [1-4]. a) Structural hierarchy of the cellulosic fiber components from the tree to the anhydroglucose molecule (SEM image of wood cell structure: courtesy of D. Dupeyre, CERMAV); b) preparation of nanocrystals by selective acid hy‐Na diffusion of the acid into the substrate, the glycosidic bonds in disordered, more accessible and reactive regions are preferentially broken. Consequently, as the hydrolysis progresses, the degree of polymerization of the cellulose macrostructures decreases, while the crystallinity of the insoluble particles increases [8].

Cellulose nanocrystal properties

In the late 1940s, cellulose crystallites were first isolated by chemical treatment of a cotton substrate in hot concentrated sulfuric acid [5]. These combined factors led to the opening of the first commercial plant by CelluForce Inc. Several review articles and books have been published in recent years that cover in detail the various aspects of the CNC functions and applications.

Figure 2. TEM images of negatively stained preparations of CNCs of various origins: a) wood (courtesy of G
Figure 2. TEM images of negatively stained preparations of CNCs of various origins: a) wood (courtesy of G

Need for CNC characterization

Lists of different sizes of CNCs obtained from various sources can be found in recent reviews and in Table 1. Particle size is a good indicator of the quality of a CNC dispersion, but direct observation of nanoparticles is still challenging and high-resolution direct imaging or light scattering techniques are required. Particle size is a good indicator of CNC dispersion quality, but direct observation of nanoparticles is still challenging and high-resolution direct imaging or light scattering techniques are required.

Microscopy and spectroscopy techniques used for CNC characterization

Accurate knowledge of the size and morphology of CNCs plays a key role in the development of many applications where these properties directly affect the properties of the final product. The stability of the suspension is due to the electrostatic repulsive forces created by the negatively charged sulfate ester groups located on the surface of the crystals. An in-depth description of sample preparation procedures and observation techniques is followed by a review of the literature on CNC TEM imaging.

TEM techniques used for the observation of CNCs

  • Selected milestones in the characterization of nanocellulose by TEM
  • Sample preparation
  • Observation techniques

More single bars were observed in the latter than in either of the other two. It therefore accumulates on one side of the nanoparticles (electron-dense region) and is absent on the other side (electron-transparent region). In that case, an increase in the lethal dose by a factor of 3 has been reported in the literature.

Figure 3. Comparison of images of unstained (a) and negatively stained (b) preparations of cotton CNCs
Figure 3. Comparison of images of unstained (a) and negatively stained (b) preparations of cotton CNCs

Review of cellulose nanocrystal imaging and size analysis

  • TEM images and size distributions of CNCs
  • TEM of CNC-hybrid composites
  • TEM of CNC-polymer nanocomposites

The measured width thus indeed corresponds to the projection of the CNC in a given orientation. For needle-shaped (and possibly ribbon-like) CNCs, the influence of the statistical errors on the measurement is. Pd on wood pulp CNCs (reproduced from [40] with permission from The Royal Society of Chemistry); B). sion of The Royal Society of Chemistry);.

Figure 10. TEM images illustrating the diversity of shapes and structures of CNCs prepared by acid hydrolysis of cot‐
Figure 10. TEM images illustrating the diversity of shapes and structures of CNCs prepared by acid hydrolysis of cot‐

Conclusion and perspectives: Challenges and solutions in imaging CNCs

Extraction and characterization of cellulose nanocrystals from corn for application as a reinforcing agent in nanocom-. One-turn biopolymer templated glass: control of chirality, porosity, and photonic properties of silica with cellulose nanocrystals. Network imaging from ultrathin sections of cellulose microfibrils in the cell wall of Valonia macrophysa Kütz.

TEM Morphology of

Carbon Nanotubes (CNTs) and its Effect on the

Life of Micropunch

  • Experimental material and procedures
    • Experimental material
    • Experimental procedures 1. CNTs synthesis
    • SEM and TEM Morphology of CNTs Coated on Micropunch CNTs micropunch
  • Results and discussion
    • SEM and TEM morphology of CNTs coated on micropunch
    • Wear loss of micropunches
    • Surface texture of CNT-coated micropunch
    • Profile of punched microholes
    • Benefit of micropunching
  • Mechanism of CNTs’ effect
  • Conclusion

When the punching is in the almost stable period, the surface texture of the micropunch is shown in Fig. When the punching process is in the almost stable period, the diameter of the punched micro‐. 8 well aligned with the wear loss of micropunches during the punching period, as shown in fig.

Figure 1. Surface texture of micropunch
Figure 1. Surface texture of micropunch

HRTEM Study on Resistive Switching ZrO 2 Thin Films and Their Micro-Fabricated Thin Films

Experiment

  • ZrO 2 thin films preparation
  • ZrO 2 lattice preparation

ZrO2 gratings were prepared by double exposure of two-beam laser interference through 90° rotation of the sample in its own plane between.

  • ZrO 2 lattice preparation
  • I-V measurement with ZrO 2 thin films
  • I-V measurement with ZrO 2 lattice
  • HRTEM sample preparation
  • Discussion and results
    • Normal probe station I-V curves
    • Local I-V curves by LC-AFM measurement systems
    • HRTEM observations
  • Conclusion

When the voltage goes to 0.5V, the current rises rapidly, which means that the OFF state changes to the ON state. When the voltage goes to 18V, the current rises rapidly, which means that the OFF state changes to the ON state. When the voltage goes to 0.8V, the current rises rapidly, which means that the OFF state changes to the ON state.

Figure 1. Observation of ZrO 2  lattice dot by AFM measurement systems.
Figure 1. Observation of ZrO 2 lattice dot by AFM measurement systems.

Hình ảnh

Figure 1. Schematics of atomistic scale devices. (a) NC, (b) ASW, (c) nano-gap structure, and (d) SMJ.
Figure 7. Conductance variation versus tip displacement in Au NCs measured by STM-AFM method.[64]
Figure 9. Time variation in elementary step of slip in shear deformation of Au NCs.[72]
Figure 9. Time variation in elementary step of slip in shear deformation of Au NCs.[72]
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