• Applied Microscopy
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• v.41 no.3
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• pp.215-222
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• 2011

We discuss the experimental procedure for extracting reliable phase information from a defocus series of transmission electron microscopy (TEM) dark-field images using the transport of intensity equation (TIE). Taking InGaN/GaN multi-quantum well light-emitting diode as a model system, various factors affecting the final result of reconstructed phase such as TEM sample preparation, TEM imaging condition, image alignment, the correction of defocus values and the use of high frequency pass filter are evaluated. The obtained phase of wave function was converted to the geometric phase of the corresponding lattice planes, which was then used for the two-dimensional mapping of lattice strain following the dark-field inline holography (DIH) routine. The strain map obtained by DIH after optimized image processing is compared with that obtained by the geometric phase analysis of high resolution TEM (HRTEM) image, manifesting that DIH yields more accurate and reliable strain information than HRTEM-based GPA.

• Journal of the Korean institute of surface engineering
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• v.35 no.5
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• pp.289-294
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• 2002

ZnTe films have been grown on (100) GaAs substrate with two representative problems. The one is lattice mismatch, the other is thermal expansion coefficients mismatch of ZnTe /GaAs. It claims here, the relationship of film thickness and defects distribution with (100) ZnTe/GaAs using hot wall epitaxy (HWE) growth was investigated by transmission electron microscopy (TEM). It analyzed on the two-sort side using TEM with cross-sectional transmission electron microscopy (XTEM) and high-resolution electron microscopy (HREM). Investigation into the nature and behavior of dislocations with dependence-thickness in (100) ZnTe/ (100) GaAs hetero-structures grown by transmission electron microscopy (TEM). This defects range from interface to 0.7 $\mu\textrm{m}$ was high density, due to the large lattice mismatch and thermal expansion coefficients. The defects of low density was range 0.7$\mu\textrm{m}$~1.8$\mu\textrm{m}$. In the thicker range than 1.8$\mu\textrm{m}$ was measured hardly defects.

• Applied Microscopy
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• v.44 no.4
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• pp.133-137
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• 2014

We suggest a facile transmission electron microscopy (TEM) specimen preparation method for the direct (polymer-free) transfer of layer-area graphene from Cu substrates to a TEM grid. The standard (polymer-based) method and direct transfer method were by TEM, high-resolution TEM, and energy dispersive X-ray spectroscopy (EDS). The folds and crystalline particles were formed in a graphene specimen by the standard method, while the graphene specimen by the direct method with a new etchant solution exhibited clean and full coverage of the graphene surface, which reduced several wet chemical steps and accompanying mechanical stresses and avoided formation of the oxide metal.

• Applied Microscopy
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• v.25 no.4
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• pp.124-131
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• 1995

High resolution transmission electron microscopic observations on the $Hg_{1-x}\;Tl_{x}\;Ba_{2}(Ca_{0.86}\;Sr_{0.14})_{2}\;Cu_{3}\;O_{8+\delta}$(x=0.00, 0.25, 0.50, 0.75) were carried out using side-entry type TEM working at 300 kV. The TEM samples are prepared by powder method. The pellets are crushed in agatar motar and suspended in $CCl_4$, solution and scooped in holely carbon microgrid. The 1223 structures are observed in all samples with [010] zone axis. Except x=0.25 sample, the lattice parameter a and c tend to decrease as the thallium contents are increased ranging from 0.3936 nm to 0.3713 nm for a, and from 1.6131 nm to 1.5138 nm for c parameter. Those of x=0.25 sample are reduced too much, 0.3785 nm for a, 1.5375 nm for c. The sample with x=0.25 shows the intergrowth of 1223 and 1234 structure with the ratio of 19 to 1. As the thallium content increases, the structures become more stable without having any defect. The samples are damaged by electron beam irradiation during the observation, however the structure can endure longer as the thallium contents are increased.

• Applied Microscopy
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• v.45 no.3
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• pp.183-188
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• 2015

Due to the miniaturization of semiconductor devices, their crystal structure on the nanoscale must be analyzed. However, scanning electron microscope-electron backscatter diffraction (EBSD) has a limitation of resolution in nanoscale and high-resolution electron microscopy (HREM) can be used to analyze restrictive local structural information. In this study, three-dimensional (3D) automated crystal orientation and phase mapping using transmission electron microscopy (TEM) (3D TEM-EBSD) was used to identify the crystal structure relationship between an epitaxially grown CdS interfacial layer and a $Cu(In_xGa_{x-1})Se_2$ (CIGS) solar cell layer. The 3D TEM-EBSD technique clearly defined the crystal orientation and phase of the epitaxially grown layers, making it useful for establishing the growth mechanism of functional nano-materials.

• Korean Journal of Materials Research
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• v.28 no.10
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• pp.595-600
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• 2018

This study investigates the microstructural properties of CoCrFeMnNi high entropy alloy (HEA) oxynitride thin film. The HEA oxynitride thin film is grown by the magnetron sputtering method using nitrogen and oxygen gases. The grown CoCrFeMnNi HEA film shows a microstructure with nanocrystalline regions of 5~20 nm in the amorphous region, which is confirmed by high-resolution transmission electron microscopy (HR-TEM). From the TEM electron diffraction pattern analysis crystal structure is determined to be a face centered cubic (FCC) structure with a lattice constant of 0.491 nm, which is larger than that of CoCrFeMnNi HEA. The HEA oxynitride film shows a single phase in which constituting elements are distributed homogeneously as confirmed by element mapping using a Cs-corrected scanning TEM (STEM). Mechanical properties of the CoCrFeMnNi HEA oxynitride thin film are addressed by a nano indentation method, and a hardness of 8.13 GPa and a Young's modulus of 157.3 GPa are obtained. The observed high hardness value is thought to be the result of hardening due to the nanocrystalline microstructure.

• Transactions on Electrical and Electronic Materials
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• v.4 no.3
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• pp.15-18
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• 2003

Aluminum oxide ($Al_2O_3$) materials were coated conformally on ZnO nanorods by atomic layer deposition (ALD). The ZnO nanorods were first synthesized on a Si(100) substrate from ball-milled ZnO powders by a thermal evaporation procedure. $Al_2O_3$ films were then deposited on these ZnO nanorods by ALD at a substrate temperature of $300^{\circ}C$ using trimethylaluminum (TMA) and distilled water ($H_2O$). Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images of the deposited ZnO nanorods revealed that amorphous $Al_2O_3$ cylindrical shells surround the ZnO nanorods. These TEM images illustrate that ALD has an excellent capability to coat any shape of nanorods conformally.

• Journal of Ocean Engineering and Technology
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• v.20 no.2 s.69
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• pp.59-65
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• 2006

Steel, as a reinforcing mechanism in concrete, provides the tensile strength that is lacking in concrete, alone, and the high alkaline environment (pH 12.5) in concrete offers satisfactory protection against most corrosion of the steel. However, the corrosion of reinforcing steel in concrete can occur by chloride attack or carbonation, and it can cause a loss of integrity a section and concrete failure through cracking and spalling. In this study, a transient electro magnetic method (TEM) of a nondestructive technique is adapted to study the measuring method of steel corrosion in mortar. The sensor was made of an enameled wire, with a diameter of 0.25mm and anacril. He sensor configuration used was a coincident loop type. The secondary electro motive force (2nd EMF) was measured with SIROTEMIII, which equipped the accelerator. The accelerator allowsthe transmitter to turn off approximately $10\sim15$ times faster than normal. The high-resolution time series, used for very shallow or a high resistivity investigation was selected. After steels were corroded by the salt spray, during 4, 8, 15 and 25 days, they were embedded in mortar. The content results acquired in this study are as follows. The variation of the secondary electro motive force (2nd EMF) was shown by the change of steel surface with different corrosion time steel. It was confirmed that measurement of steel corrosion in mortar by a transient electro-magnetic method (TEM) can be possible.

• Applied Microscopy
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• v.50
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• pp.28.1-28.6
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• 2020

Contamination on two-dimensional (2D) crystal surfaces poses serious limitations on fundamental studies and applications of 2D crystals. Surface residues induce uncontrolled doping and charge carrier scattering in 2D crystals, and trapped residues in mechanically assembled 2D vertical heterostructures often hinder coupling between stacked layers. Developing a process that can reduce the surface residues on 2D crystals is important. In this study, we explored the use of atomic force microscopy (AFM) to remove surface residues from 2D crystals. Using various transmission electron microscopy (TEM) investigations, we confirmed that surface residues on graphene samples can be effectively removed via contact-mode AFM scanning. The mechanical cleaning process dramatically increases the residue-free areas, where high-resolution imaging of graphene layers can be obtained. We believe that our mechanical cleaning process can be utilized to prepare high-quality 2D crystal samples with minimum surface residues.

• Tribology and Lubricants
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• v.26 no.2
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• pp.122-128
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• 2010

Focused Ion Beam (FIB) has been used for site-specific TEM sample preparation and small scale fabrication. Moreover, analysis on the surface microstructure and phase distribution is possible by ion channeling contrast of FIB with high resolution. This paper describes FIB applications and deformed surface structure induced by sliding. The effect of FIB process on the surface damage was explored as well. The sliding experiments were conducted using high purity aluminum and OFHC(Oxygen-Free High Conductivity) copper. The counterpart material was steel. Pin-on-disk, Rotational Barrel Gas Gun and Explosively Driven Friction Tester were used for the sliding experiments in order to investigate the velocity effect on the microstructural change. From the FIB analysis, it is revealed that ion channeling contrast of FIB has better resolution than SEM and the tribolayer is composed of nanocrystalline structures. And the thickness of tribolayer was constant regardless of sliding velocities.