• Applied Microscopy
• /
• v.24 no.4
• /
• pp.132-144
• /
• 1994

The application of TEM in investigating the evolution of microstructure during solid phase crystallization of the amorphous Si, $Si_{1-x}Ge_x,\;and\;Si_{1-x}Ge_x/Si$ films deposited on $SiO_2$ substrate, in identifying the failure mechanism of the TiN barrier layer in the Cu-metallization scheme, and in comparing the microstructure of the as-deposited Cu-Cr and Cu-Ti alloy films are discussed. First, it is identified that the evolution of microstructure in Si and $Si_{1-x}Ge_x$ alloy films strongly depends on the concentration of Ge in the film. Second, the failure mechanism of the TiN diffusion barrier in the Cu-metallization is the migration of the Cu into the Si substrate, which results in the formation of a dislocation along the Si {111} plane and precipitates (presumably $Cu_{3}Si$) around the dislocation. Finally, the microstructure of the as-deposited Cu-Cr and Cu-Ti alloy films is also quite different in these two cases. From these several cases, we demonstrate that the information which we obtained using TEM is critical in understanding the behavior of materials.

• Applied Microscopy
• /
• v.42 no.4
• /
• pp.218-222
• /
• 2012

Modern aberration-corrected transmission electron microscope (TEM) with appropriate electron beam energy is able to achieve atomic resolution imaging of single and bilayer graphene sheets. Especially, atomic configuration of bilayer graphene with a rotation angle can be identified from the direct imaging and phase reconstructed imaging since atomic resolution Moir$\acute{e}$ pattern can be obtained successfully at atomic scale using an aberration-corrected TEM. This study boosts a reliable stacking order analysis, which is required for synthesized or artificially prepared multilayer graphene, and lets graphene researchers utilize the information of atomic configuration of stacked graphene layers readily.

• Applied Microscopy
• /
• v.46 no.3
• /
• pp.167-169
• /
• 2016

Solder/electroless nickel immersion gold (ENIG) joint sample which is comprised of dissimilar materials with different mechanical properties has limited the level of success in preparing thin samples for transmission electron microscopy (TEM). This short technical note reports the operation parameters for ultramicrotomy of solder joint sample and TEM analysis results. The solder joint sample was successfully sliced to 50~70 nm thick lamellae at slicing speed of 0.8~1.2 mm/s using a boat-type $45^{\circ}$ diamond knife. Ultramicrotomy can be applied as a routine sample preparation technique for TEM analysis of solder joints.

• Applied Microscopy
• /
• v.27 no.3
• /
• pp.257-263
• /
• 1997

Microstructural characterizations of II-VI blue laser diodes which consist of quaternary $Zn_{1-x}Mg_xS_ySe_{l-y}$ cladding layer, ternary $ZnS_ySe_{l-y}$ guiding layer and $Zn_{0.8}Cd_{0.2}Se$ quantum well as active layer were carried out using the transmission electron microscope working at 300 kV. Even though the entire structure is pseudomorphic to GaAs substrate, the structure had contained numerous extended stacking faults and dislocations which had created at ZnSe/GaAs interfaces and then further grown to the top of the epilayers. These faults might be expected to cause the degradation and shortening the lifetime of laser devices.

• Applied Microscopy
• /
• v.38 no.4
• /
• pp.383-386
• /
• 2008

In performing in situ heating transmission electron microscopy (TEM) for materials characterizations, arising concerns such as specimen drifts and unintentional Cu contamination are discussed. In particular, we analysed the thermal and mechanical characteristics of in situ heating holders to estimate thermal drift phenomena. From the experimental results, we suggest an empirical model to describe the thermal drift behavior so that we can design an effective plan for in situ heating experiment. Practical approaches to minimize several hindrances arisen from the experiment are proposed. We believe that our experimental recommendations will be useful for a microscopist fascinated with the powerful potential of in situ heating TEM.

• Ceramist
• /
• v.22 no.4
• /
• pp.417-428
• /
• 2019

Even though, nanoscale materials of various shapes and compositions have been synthesized in the liquid, their underlying growth and transformation mechanisms are not well understood due to a lack of analytical methods. The advent of liquid cell for transmission electron microscope (TEM) enables the direct imaging of chemical reactions that occur in liquids with nanometer resolution of the electron microscope (EM). Here, the technical development of liquid cell TEM equipment and their applications to the study of nanomaterials analysis in liquid are discussed. Also new findings discovered through liquid cell TEM studies such as nucleation & growth, coalescence process and transformation are discussed.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.9
• /
• pp.1303-1307
• /
• 2003

The low molecular water-soluble chitosan nanoparticles (LMWSC-NPs) were prepared, which was modified with hydrophilic and hydrophobic moieties to evaluate the potential for pharmaceutics application. The synthesis of LMWSC-NPs was identified by FT-IR and $^1H$-NMR spectra. Also, we measured the photon correlation spectroscopy (PCS), transmission electron microscope (TEM) and atomic force microscope (AFM) to investigate the characteristics and morphology of the LMWSC-NPs. At the PCS measurement, the more increase the number of substitutive group, the more decrease the positive charge of LMWSC-NP surface. From the results of TEM and AFM, spherical morphologies were observed, and their sizes were 30-150 nm. Resultantly, LMWSC-NPs prepared in this experiment will be expected as a suitable device for the drug targeting system.

• Transactions on Electrical and Electronic Materials
• /
• v.7 no.4
• /
• pp.173-179
• /
• 2006

Due to the limitations of the channel length, the lateral spread for two-dimensional impurity distributions is critical for the analysis of devices including the integrated complementary metal oxide semiconductor (CMOS) circuits and high frequency semiconductor devices. The developed codes were then compared with the two-dimensional implanted profiles measured by transmission electron microscope (TEM) as well as simulated by a commercial TSUPREM4 for verification purposes. The measured two-dimensional TEM data obtained by chemical etching-method was consistent with the results of the developed analytical model, and it seemed to be more accurate than the results attained by a commercial TSUPREM4. The developed codes can be applied on a wider energy range $(1KeV{\sim}30MeV)$ than a commercial TSUPREM4 of which the maximum energy range cannot exceed 1MeV for the limited doping elements. Moreover, it is not only limited to diffusion process but also can be applied to implantation due to the sloped and nano scale structure of the mask.

• Macromolecular Research
• /
• v.16 no.2
• /
• pp.163-168
• /
• 2008

Polystyrene/gold nanoparticle (PS/AuNP) composite fibers were fabricated using an electrospinning technique. Transmission electron microscopy (TEM) showed that the diameters of the naphthalenethiol-capped gold nanoparticles (prior to incorporation into the PS fibers) ranged from 2 to 5 nm. UV-vis spectroscopy revealed the surface plasmon peaks of the gold nanoparticles centered at approximately 512 nm, indicating that nano-sized Au particles are well-dispersed in solution. This was consistent with the TEM observations. The electrospun nanofibers of PS/AuNP composites were approximately 60-3,000 nm in diameter. The surface morphology of the PS/AuNP composite and the dispersability of the Au nanoparticles inside of PS after electrospinning process were investigated by SEM and TEM. The thermal behavior of the pure PS and PS/AuNP nanocomposites and fibers were examined by DSC.

• Bulletin of the Korean Chemical Society
• /
• v.22 no.9
• /
• pp.948-952
• /
• 2001

Periodic mesoporous organosilicas with rope-based morphology from a reaction gel composition of 1 BTME : 0.57 ODTMABr : 2.36 NaOH : 353 H2O were synthesized. While long rope-shaped product dominated in case of static synthesis condition , gyroid type products instead of rope shaped product appeared and rope shaped product disappeared with agitation. PMO with such a long rope shaped morphology is firstly reported. Additionally, various rope-based morphologies depending on the degree of bending, twisting, folding and winding of rope such as spirals, discoids, toroids, and worm-like aggregates were observed. White powdered products were characterized by X-ray diffraction, N2 sorption measurement, SEM and TEM. From XRD pattern and TEM image, ODTMA-PMO with hexagonal symmetry was identified. The pore diameter and BET surface area of ODTMA-PMO are $32.9{\AA}$ and 799 m2g-1 , respectively. Hexagonally arrayed channels run with long axis of rope and rope-based shapes with various degree of curvature, which was elucidated by using TEM images.