• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.115-130
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• 1995

In order to produce Cu nanocrystallite in silicon wafer, the implantation technique was used. The samples of silicon (100) wafers were implanted by $Cu^+$ ions at 100 keV and with varying the doses at room temperature. Post-annealing was performed at $800^{\circ}C$ with Ar environment. To investigate the formation of Cu nanocrystallite with ion doses and growth process by thermal annealing, SIMS and HRTEM(high resolution transmission electron microscopy)spectra were studied.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.726-729
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• 1995

We investigated the effects of Sm on the microstructure and magnetic properties of Fe-Co Alloy films prepared by a DC triode sputtering. The magnetostriction was found to be changed with the Sm content from positive to negative values, taking a zero magnetostriction was at about 3 at% Sm. The Sm content dependence of magnetostriction was explained by the formation of Sm enriched amorphous phase surrounding the main bcc (Fe,Co) crystalline phase, which was observed by a high resolution transmission electron microscopy.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3046-3054
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• 2013

Synthesis of Carbon Nanotube bundles has been achieved by simple and economical solvothermal procedure at very low temperature of $180^{\circ}C$. The product yield obtained was about 70-75%. The optimization of reaction conditions for an efficient synthesis of CNTs has been presented. The CNTs are obtained by reduction of hexachlorobenzene in the presence of Na/Ni in cyclohexane. The X-ray diffraction, Fourier transform infrared and Raman spectral studies have inferred us the graphene structure of the products. The CNTs formed as the bundles were viewed on scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscope. These are the multiwalled CNTs with outer diameter of 5-10 nm, the inner diameter 2-4 nm and cross sectional diameter up to 5 nm. Brunauer-Emmett-Teller (BET) based $N_2$ gas adsorption studies have been made to obtain BET surface area and $H_2$ storage capacity. Effect of the experimental variables such as reaction temperature, amount of catalyst and the amount of carbon source were investigated. It is found that they affect significantly on the product nature and yield.

• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.35-42
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• 1998

- The Si-$SiO_2$ interface of silicon on insulator (SOI) formed by 100 keV $O^+$ was ohserved using high resolution transmission electron microscopy (HRTEM), before and after annealing. The interface of as-implanted sample, ~$5\times 10^{17}\textrm{cm}^{-2}O^+$ implanted at $550^{\circ}C$ was very rough and it has many defectsoxide precipitate, stacking fault, coesite $SiO_2$ etc. However, the interface became flat by high temperature annealing at $1300^{\circ}C$ for 4 hour. It's roughness, observed by HRTEM, was comparable to the interface roughness of 3 keV $O_2^\;+$ ion beam oxide and -6 nm gate oxide formed by thermal oxidation.

• Korean Journal of Metals and Materials
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• v.46 no.7
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• pp.458-463
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• 2008

High purity Fe thin films were prepared by the ion beam deposition method with $^{56}Fe^{+}$ions on the Si substrate at the room temperature. The Fe thin films were deposited at the ion energy of 50 eV and 100 eV. Microstructural properties were investigated on the atomic scale using high-resolution transmission electron microscopy (HRTEM). It was found that the Fe thin film obtained with the energy of 50 eV having an excellent corrosion resistance consists of the amorphous layer of ~15 nm in thickness and the bcc crystalline layer of about 30 nm in grain size, while the thin film obtained with the energy of 100 eV having a poor corrosion resistance consists of little amorphous layer and the defective crystalline layer. Furthermore the crystal structures and arrangements of the oxide layers formed on the Fe thin films were analyzed by processing of the HRTEM images. It was concluded that the corrosion behavior of Fe thin films relates to the surface morphology and the crystalline structure as well as the degree of purification.

• Applied Microscopy
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• v.45 no.1
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• pp.1-8
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• 2015

We have developed a new HD-2700 (Hitachi High-Technologies Corp., Japan) scanning transmission electron microscope (STEM) that includes an automatic aberration correction function, and a large-solid-angle energy-dispersive X-ray spectroscopy detector that enables high-resolution and sensitive analysis. For observation with atomic resolution, using spherical-aberration-corrected STEM, in order that satisfactory performance of the device can be achieved readily, and within a short time, irrespective of the operator's skill level, a spherical-aberration-correction device with an automatic aberration-correction function was developed. This automatic aberration-correction function carries out the entire correction-related process (aberration measurement, selection and correction) automatically, with automatic selection of the aberrations that require correction, and automatic measurement of the appropriate corrections.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.535-536
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• 2013

본 연구에서는 DC/RF co-sputtering공법을 통해 제작한 In-Mo-O 투명 Mo doping 농도 및 열처리 온도에 따른 전기적, 광학적, 구조적 특성을 분석하고, 최적화된 In-Mo-O 투명전극을 유기태양전지(OPVs)와 유기발광다이오드(OLED)에 적용하여 그 가능성을 평가하였다. Mo doping 농도는 co-sputtering 공정 중 MoO3에 인가되는 radio-frequency (RF) power를 변화시켜 조절되었으며, 투명전극의 광학적 특성 및 전기적 특성 향상을 위해 성막 공정 후 급속 열처리 공정을 온도 별로 진행하였다. In-Mo-O 투명 전극은 Mo 도핑 농도에 영향을 받음을 확인할 수 있었고, 최적화된 Mo doping 파워에서 성막한 In-Mo-O 박막은 급속 열처리 공정 후 면저항 24.57 Ohm/square, 투과도 81.57% (400~1,200 nm wavelength)를 나타내었다. Bulk hetero-junction 기반의 고효율 유기태양전지와 유기발광다이오드 적용하기 위해 본 연구에서 제작된 IMO 투명전극의 구조적 특성, 결정성 및 표면특성은 x-ray diffraction (XRD), atomic force microscopy(AFM), field effect scanning electron microscopy (FE-SEM), High-resolution transmission electron microscopy (HRTEM) 분석을 통해 진행하였다. In-Mo-O 투명 전극상에 제작된 OLEDs와 OPV는 reference ITO 전극에 제작된 OLEDs/OPV와 비교할 때 유사하거나 향상된 특성을 나타내었으며 이는 In-Mo-O 박막이 OLED/OPV용 투명 전극으로 적용이 가능함을 말해준다.

• Korean Journal of Materials Research
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• v.31 no.1
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• pp.23-28
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• 2021

The purpose of this study is to prepare WO3 nanopowders by high-energy milling in mixture gas (7 % H2+Ar) with various milling times (10, 30, and 60 min). The phase transformation, particle size and light absorption properties of WO3 nanopowders during reduction via high-energy milling are studied. It is found that the particle size of the WO3 decreases from about 30 ㎛ to 20 nm, and the grain size of WO3 decreases rapidly with increasing milling time. Furthermore, the surface of the particles due to the pulverization process is observed to change to an amorphous structure. UV/Vis spectrophotometry shows that WO3 powder with increasing milling times (10, 30, 60 min) effectively extends the light absorption properties to the visible region. WO3 powder changes from yellow to gray and can be seen as a phenomenon in which the progress of the color changes to blue. The characterization of WO3 is performed by high resolution X-ray diffractometry, Field emission scanning electron microscopy, Transmission electron microscopy, UV/Vis spectrophotometry and Particle size analysis.

• Korean Journal of Materials Research
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• v.21 no.3
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• pp.168-173
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• 2011

Precipitation of the ordered icosahedral quasicrystal in Mg-6wt%Zn-1wt%Y alloy has been characterized by transmission electron microscopy observations. The lamellar-type icosahedral qusicrystal phases (I-phase) with the face-centered icosahedral (FCI) structure are observed in alloy after solution treatment at $550^{\circ}C$. In the alloy annealed at $400^{\circ}C$, polygon-shaped I-phases are observed in the ${\alpha}$-Mg matrix. The interfaces of the I-phase with the matrix are facetted and the facets are on five-fold and two- fold plane of the I-phase. The orientation relationship of the I-phase with the matrix is determined to be $[I5]_I//[001]_{Mg}$, $(2f)_I//(2\overline{1}0)_{Mg}$ and $[I2]_I//[311]_{Mg}$, $(5f)_I//(0\overline{1}1)_{Mg}$. The icosahedral grains are occasionally found to be twinned with one of the five-fold axis as the twin axis. The twin boundaries appear to be fairly straight and perpendicular to the fivefold twin axis. The icosahedral twin can be expressed as a rotation of $63.4^{\circ}$ or $116.62^{\circ}$ around two fold zone axis.

• Carbon letters
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• v.28
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• pp.72-80
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• 2018

In this study, an empirical relationship between the energy band gap of multi-walled carbon nanotubes (MWCNTs) and synthesis parameters in a chemical vapor deposition (CVD) reactor using factorial design of experiment was established. A bimetallic (Fe-Ni) catalyst supported on $CaCO_3$ was synthesized via wet impregnation technique and used for MWCNT growth. The effects of synthesis parameters such as temperature, time, acetylene flow rate, and argon carrier gas flow rate on the MWCNTs energy gap, yield, and aspect ratio were investigated. The as-prepared supported bimetallic catalyst and the MWCNTs were characterized for their morphologies, microstructures, elemental composition, thermal profiles and surface areas by high-resolution scanning electron microscope, high resolution transmission electron microscope, energy dispersive X-ray spectroscopy, thermal gravimetry analysis and Brunauer-Emmett-Teller. A regression model was developed to establish the relationship between band gap energy, MWCNTs yield and aspect ratio. The results revealed that the optimum conditions to obtain high yield and quality MWCNTs of 159.9% were: temperature ($700^{\circ}C$), time (55 min), argon flow rate ($230.37mL\;min^{-1}$) and acetylene flow rate ($150mL\;min^{-1}$) respectively. The developed regression models demonstrated that the estimated values for the three response variables; energy gap, yield and aspect ratio, were 0.246 eV, 557.64 and 0.82. The regression models showed that the energy band gap, yield, and aspect ratio of the MWCNTs were largely influenced by the synthesis parameters and can be controlled in a CVD reactor.