• 마이크로전자및패키징학회지
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• 제20권1호
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• pp.27-31
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• 2013

Copper-oxide (CuO) thin films were prepared by reactive sputtering of Cu onto Si wafers and characterized using a statistical design of experiments approach. The most significant factor in controlling the electrical resistivity and deposition rate was determined to be the $O_2$ fraction. The deposited CuO thin films were characterized in terms of their physical and chemical properties, using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), X-ray diffraction (XRD), and 4-point resistance measurements. The deposited copper thin films were characterized by XPS and XRD analyses to consist of $Cu^{2+}$. The CuO thin films of highest resistivity exhibited superior rectifying responses with regard to n-type Si wafers, with a current ratio of $3.8{\times}10^3$. These superior responses are believed to be associated with the formation of a charge-depletion region originating from the p-type CuO and n-type Si materials.

• Carbon letters
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• 제7권1호
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• pp.34-41
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• 2006

The objective of this paper is to compare the variation of surface properties by hydrochloric acid pre-treatment and of metallic potassium and their salts loading effect for activated carbon after surfaces transformation by acid. From the results of nitrogen adsorption, each isotherm shows a distinct knee band, which is closely related to the characteristic of microporous carbons with capillary condensation in micropores. In order to present the causes of the differences in surface properties and $S_{BET}$ after the samples were treated with hydrochloric acid, pore structure and surface morphology are investigated by adsorption analysis. X-ray diffraction (XRD) patterns indicate that activated carbons show better performance for metallic potassium and potassium salts by pre-treatment with hydrochloric acid. Scanning electron microscopy (SEM) pictures of potassium/activated carbon particles provide information about the homogeneous distribution of metal or metal complex on the surface. For the chemical composition microanalysis for potassium treatment of the activated carbon pre-treated with hydrochloric acid, samples were analyzed by energy disperse X-ray (EDX). Finally, the type and quality of oxygen groups are determined from the method proposed by Boehm. A positive influence of the acidic groups on the carbon surface by acid treatment is also demonstrated by an increase in the contents of potassium salts with increasing of acidic groups calculated from Boehm titration.

• Transactions on Electrical and Electronic Materials
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• 제1권2호
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• pp.12-17
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• 2000

Helicon waves were excited by a Nagoya type III antenna in magnetized plasma, and hydrogen and methane are fed through a Mass Flow Controller(MFC). We made a diagnosis of properties of helicon plasma by H$_2$gaseous discharge, and fabricated the diamond thin film. The maximum measured electron density was 1${\times}$10$\^$10/ cm$\^$-3/. Diamond films have been growo on (100) silicon substrate using the helicon plasma chemical vapor deposition. Diamond films were deposited at a pressure of 0.1 Torr, deposition time of 40~80 h, a substrate temperature of 700$^{\circ}C$ and methane concentrations of 0.5~2.5%. The growth characteristics were investigated by means of X-ray Photoelectron (XPS) and X-ray Diffraction(XRD), XRD and XPS analysis revealed that SiC was formed, and finally diamond particles were definitely deposited on it. With increasing deposition time, the thickness and crystallization of the daimond thin film increased, For this system the optimum condition of methane concentration was estimated to near to 1.5%.

• Carbon letters
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• 제18권
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• pp.37-42
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• 2016

Graphene was grown on molybdenum (Mo) foil by a chemical vapor deposition method at different growth temperatures (1000℃, 1100℃, and 1200℃). The properties of graphene were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and Raman spectroscopy. The results showed that the quality of the deposited graphene layer was affected by the growth temperature. XRD results showed the presence of a carbide phase on the Mo surface; the presence of carbide was more intense at 1200℃. Additionally, a higher I_2D/I_G ratio (0.418) was observed at 1200℃, which implies that there are fewer graphene layers at this temperature. The lowest I_D/I_G ratio (0.908) for the graphene layers was obtained at 1200℃, suggesting that graphene had fewer defects at this temperature. The size of the graphene domains was also calculated. We found that by increasing the growth temperature, the graphene domain size also increased.

• Transactions on Electrical and Electronic Materials
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• 제3권3호
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• pp.29-33
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• 2002

A procedure was developed for preparing bulk carbon nitride crystals from a polymeric $\alpha$ -C$_3$N$\_$4.2/ at high pressure and temperature in the presence of seeds of crystalline carbon nitride films prepared by a high voltage discharge plasma combined with pulsed laser ablation of graphite target. The samples were evaluated by x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, Auger electron spectroscopy (AES), secondary-ion mass spectrometry (SIMS), scanning electron microscopy (SEM) and x-ray diffraction (XRD). Notably, XPS studies of the film composition before and after thermobaric treatments demonstrate that the nitrogen composition in $\alpha$ -C$_3$N$\_$4.2/ material initially containing more than 58% nitrogen decreases during the annealing process and reaches a common, stable composition of ~45%. The thermobaric experiments were performed at 10-77 kbar and 350-1200 $\^{C}$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.363-366
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• 2000

In this study, SrBi$_2$Ta$_2$$O_{9}$ (SBT) thin films were etched at different Cl$_2$gas mixing ratio in Cl$_2$/Ar. The maximum etch rate of SBT was 883 $\AA$/min in Cl$_2$(20%)/Ar(80%). The result indicates that physical sputtering of charged particles is dominant to chemical reaction in etching SBT thin films. To evaluate the changes of morphology and crystallinity on the near surface of etched SBT, atomic force microscopy (AFM) and x-ray diffraction (XRD) were used. The rms values of etched samples in Ar only or Cl$_2$ only plasma were higher than that of as-deposited, Cl$_2$/Ar Plasma. The SBT (105) crystalinity of the etched samples decreased in Af only or Cla only plasma, but maintain constant in ClyAr plasma. This can be illustrated by a decrease of Bi content or nonvolatile etching products (Sr-Cl and Ta-Cl), resulting in the changes of stoichiometry on the etched surface of the SBT thin films. The decrease of Bi content and nonvolatile etch products were revealed by x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS).).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.190.2-190.2
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• 2013

Vanadium dioxide ($VO_2$) has been widely attracted for academic research and industrial applications due to its metal-insulator transition (MIT) temperature close to room temperature. We synthesized VOx film on (0001) sapphire substrate with vanadium target (purity: 99.9%) using DC magnetron sputtering in Ar ambience at a pressure of $10^{-3}$ Torr at $400{\sim}700^{\circ}C$. The VOx film subsequently was annealed at difference temperatures in ambience of Ar and $O_2$ gas mixture at $60{\sim}800^{\circ}C$. The structural properties of the films were investigated using scanning electron microscopic (SEM), x-ray diffraction (XRD) and x-ray absorption fine structure (XAFS) measurements. SEM reveal that small grains formed on the substrates with a roughness surface. XRD shows oriented $VO_2$(020) crystals was deposited on the $Al_2O_3$(006) substrate. From I-V measurements, the electric resistance near its MIT temperature were dramatically changed by ${\sim}10^4$ during heating and cooling the films. We will also discuss the temperature-dependent local structural changes around vanadium atoms using XAFS measurements.

• 대한금속재료학회지
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• 제48권7호
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• pp.674-682
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• 2010

Fe-fullerene/$TiO_2$ composite photocatalysts were prepared with titanium (IV) n-butoxide (TNB) by a sol-gel method. The samples were characterized by scanning electron microscopy (SEM), Transmission electron microscope (TEM), specific surface area (BET), X-ray diffraction analysis (XRD) and energy dispersive X-ray spectroscopy (EDX). The photocatalytic activities were evaluated by the photocatalytic degradation of methylene blue (MB) solution. XRD patterns of the composites showed that the Fe-fullerene/$TiO_2$ composite contained a typical single and clear anatase phase. The surface properties shown by SEM present a characterization of the texture on Fe-fullerene/$TiO_2$ composites and showed a homogenous composition in the particles for the titanium sources used. The EDX spectra for the elemental identification showed the presence of C and Ti with strong Fe peaks for the Fe-fullerene/$TiO_2$ composite. From the photocatalytic results, the excellent activity of the Fe-fullerene/$TiO_2$ composites for degradation of methylene blue under UV light irradiation could be attributed to both the effects between photocatalytic reaction of the supported $TiO_2$, decomposition of the organometallic reaction by the Fe compound and energy transfer effects such as electron and light of the fullerene.

• Bulletin of the Korean Chemical Society
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• 제21권7호
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• pp.679-684
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• 2000

The Sr2Co0.5Nb(Ta)0.5O4 and Sr3CoNb(Ta)O7 compounds, both with Ruddlesden-Popper structures, have been synthesized by the ceramic method at $1150^{\circ}C$ under atmospheric pressure. The crystallographic structure of the compounds was assigned to the tetr agonal system with space group 14/mmm by X-ray diffraction(XRD) Rietveld refinement. The reduced lattice volume and lattice parameters increased as the Ta with 5d substitutes for the Nb with 4d in the compounds. The Co/Nb(Ta)O bond length has been determined by X-ray absorption spectroscopic(EXAFS/XANES) analysis and the XRD refinement. The CoO6,octahedra were tetragonally distorted by elongation of Co-O bond along the c-axis. The magnetic measurement shows the compounds Sr2Co0.5Nb(Ta)0.5O4 and Sr3CoNb(Ta)O7 have paramagnetic properties and the Co ions with intermediate spin sates between high and low spins in D4h symmetry. All the compounds showed semiconducting behavior whose electrical conductivity increased with temperature up to 1000 K. The electrical conductiviy increased and the activation energy for the conduction decreased as the number of perovskite layers increased in the compounds with chemical formula An+1BnO3n+1.

• 한국지반환경공학회 논문집
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• 제12권5호
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• pp.37-42
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• 2011

본 연구는 부산항만 내에 퇴적된 퇴적물에 대한 현재의 성분 및 혐기성 상태에서의 잠재메탄발생량을 평가하기 위해 수행되었다. 부산항만 내 10곳의 지점을 선정하여 퇴적물을 채취하였고, 퇴적물 특성을 파악하기 위해 특성을 강열감량, 원소분석, XRD, XRF 분석을 실시하였다. 모든 특성을 구성성분은 균일하였으며, 강열감량 경우 8~10% 높은 값을 보였다. 총 5개의 시료에 대한 BMP 실험 경우 최대메탄발생량은 11.9~15.5mL methane/g VS로 시료간에 편차가 존재하였다. 기존 연구와 비교 시 음식물과 종이류에 비해 발생되는 메탄양은 작으나 발생속도는 5배에서 20배가량 큰 값을 보여주었다.