• 한국진공학회지
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• 제9권4호
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• pp.315-320
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• 2000

본 연구에서는 강유전체 박막을 게이트 산화물로 사용한 $Pt/Sr_{0.8}Bi_{2.4}Ta_2O_{9}(SBT)/ZrO_2Si$(MFIS)와 Pt/SBT/Si(MFS)구조의 결정 구조 및 전기적 성질을 고찰하였다. XRD 및 SEM측정 결과 SBT/ZrO$_2$/Si 구조의 경우 SBT/Si구조에 비해 SBT 박막이 더 큰 결정립이 형성되었다. AES분석 결과 $ZrO_2$ 박막을 완충층으로 사용함으로써 SBT 박막과 Si 기판의 상호반응을 적절히 억제할 수 있음을 확인하였다. Pt/SBT/$ZrO_2/Pt/SiO_2$/Si와 Pt/SBT/Pt/$SiO_2$/Si 구조에서 Polarization-Voltage(P-V) 특성을 비교해 본 결과 $ZrO_2$ 박막의 도입에 따라 잔류분극값은 감소하였고 항전계값은 증가하였다. MFIS 구조에서 메모리 윈도우값은 항전계값과 직접적 관련이 있으므로 이러한 항전계값의 증가는 MFIS 구조에서의 메모리 윈도값이 증가할 수 있음을 나타낸다. Pt/SBT(210 nm)/$ZrO_2$/ (28 m)/Si 구조에서 Capacitance-Voltage(C-V) 측정 결과로부터 인가전압 4~6 V에서 메모리 윈도우 가 1~1.5V정도로 나타났다. Pt/SBT/ZrO$_2$/Si구조에서 전극을 갓 증착한 경우와 산소분위기 $800^{\circ}C$에서 후열처리한 경우의 전류 밀도는 각각 약 $8\times10^{-8} A/\textrm{cm}^2$와 $4\times10^{-8}A/\textrm{cm}^2$ 정도의 값을 나타내었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.298-301
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• 2007

Magnesium alloy sheets have unique mechanical properties such as high in-plane anisotropy/asymmetry of yield stress and hardening response. The unusual mechanical behavior of magnesium alloys has been understood by the limited symmetry crystal structure of HCP metals or by deformation twinning. In the present study, the continuum plasticity models considering the unusual plastic behavior of magnesium alloy sheet were derived for a finite element analysis. A new hardening law based on two-surface model was developed to consider the general stress-strain response of metal sheets such as Bauschinger effect, transient behavior and the unusual asymmetry. Three deformation modes observed during the continuous tension/compression tests were mathematically formulated with simplified relations between the state of deformation and their histories. In terms of the anisotropy and asymmetry of the initial yield stress, the Drucker-Prager's pressure dependent yield surface was modified to include the anisotropy of magnesium alloys.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1514-1516
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• 1999

This paper covers our efforts to improve the low carrier mobility and light instability of hydrogenated amorphous silicon (a-Si:H) films with microcrystalline silicon $({\mu}c-Si)$ films. We successfully prepared ${\mu}c-Si$ films on $CaF_2$/glass substrate by decomposition of $SiH_4$ in RPCVD system. The $CaF_2$ films on glass served as a seed layer for ${\mu}c-Si$ film growth. The XRD analysis on $CaF_2$/glass illustrated a (111) preferred $CaF_2$ grains with the lattice mismatch less than 5 % of Si. We achieved ${\mu}c-Si$ films with a crystalline volume fraction of 61 %, (111) and (220) crystal orientations. grain size of $706\AA$, activation energy of 0.49 eV, and Photo/dark conductivity ratio of 124. By using a $CaF_2$/glass structure. we were able to achieve an improved ${\mu}c-Si$ films at a low substrate temperature of $300^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.85.2-85.2
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• 2010

$Cu_2ZnSnSe_4$ (CZTSe) is one of candidate to alternate $Cu(In,Ga)Se_2$ as solar absorber material for solar cell. The expensive elements of In and Ga are replaced by Zn and Sn, respectively to lower the material cost. In this study we fabricated CZTSe thin film by selenization of single precursor layer consisted metallic constituent. Precursor compositions ratio were selected to have Cu-poor and Zn-rich content and prepared by RF magnetron sputtering. Thermal processing was applied to introduce selenium into as-deposited films at temperatures ranging from 350 to 500 for time up to 120 minutes. Single precursor films showed amorphous structure and consist of individual elements of Cu, Zn, and Sn. It was confirmed by XRD analysis that synthesis of CZTSe compound is occurred from lower temperature process, although concurrently additional phases such as binary cooper selenides are also existed. The quality of CZTSe crystal was improved as temperature increased. We also investigated the optical and electrical properties of as-selenized CZTSe as well.

• Bulletin of the Korean Chemical Society
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• 제25권4호
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• pp.480-484
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• 2004

$LiGaO_2$ films have been grown on Si (100) substrates using a new single precursor $[Li(OCH_2CH_2OCH_3)_2-Ga(CH_3)_2]_2$ under high vacuum conditions $(5{\times}10^{-6}Torr)$. The $[Li(OCH_2CH_2OCH_3)_2Ga(CH_3)_2]_2$ was synthe-sized and characterized by using spectroscopic methods and single-crystal X-ray diffraction analysis. The chemical composition, crystalline structure, and morphology of the deposited films were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. The results show that polycrystalline $LiGaO_2$ films preferentially oriented in the [010] direction can be deposited on Si (100) at 500-550$^{\circ}C$ by metal organic chemical vapor deposition (MOCVD). The single precursor $[LiOCH_2CH_2OCH_3)_2-Ga(CH_3)_2]_2$ has been found suitable for chemical vapor deposition of $LiGaO_2$ thin films on Si substrates.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.2981-2984
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• 2012

Active site mapping has been done for ${\Delta}^5$-3-ketosteroid isomerase (KSI) by analyses of paramagnetic effect on $^1H-^{15}N$ HSQC spectra using 4-hydroxyl-2,2,6,6-tetramethylpiperidinyl-1-oxy (HyTEMPO) and an intermediate analog (equilenin). Our result revealed that residues in hydrophobic cavity of KSI, particularly active site region, mainly experienced a high line-broadening effect of NMR signal with HyTEMPO, while they experienced full recovery of a lineshape upon the addition of equilenin. The mapped region was very similar to the active site of KSI as described by the crystal structure. These observations indicate that a combined use of paramagnetic reagent and substrate (or analog) could rapidly identify the residues in potential active site of KSI, and can be applied to the analysis of both active site and function in unknown protein.

• 한국물환경학회지
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• 제16권4호
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• pp.555-563
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• 2000

The study was conducted to evaluate the adsorption equilibrium of heavy metals on bone charcoal made of livestock bone which was sintered at $550{\sim}600^{\circ}C$. Analysis of bone charcoal by XRD and FT-IR showed that crystal structure was similar to that of synthetic hydroxyapatite. Adsorption equilibrium capacity of single component (Pb, Cd, and Zn) on bone charcoal could be expressed as Langmuir, Freundlich, and Sips equations. Sips isotherm was best among the three isotherms. The values predicted by IAST(ideal adsorbed solution theory) showed good relationship to the experimental data in multicomponent adsorption equilibrium. Adsorption affinity was in order of Pb, Cd, and Zn. The order was same in case of activated carbon or synthetic hydroxyapatite. Through the study results. it would be expected that bone charcoal made of livestock could be used in field of wastewater treatment plants as adsorbent to remove heavy metal.

• Bulletin of the Korean Chemical Society
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• 제27권10호
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• pp.1572-1576
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• 2006

A dimeric precursor, $[Cu(dmae)(OCOCH_3)(H_2O)]_2$ for the CVD of copper metal films, (dmaeH = N,N-dimethylaminoethanol) was synthesized by the reaction of copper(II) acetate monohydrate ($Cu(OCOCH_3)_2{\cdot}H_2O$) and dmaeH in toluene. The product was characterized by m.p. determination, elemental analysis and X-ray crystallography. Molecular structure of $[Cu(dmae)(OCOCH_3)(H_2O)]_2$ shows that a dimeric unit $[Cu(dmae)(OCOCH_3)(H_2O)]_2$ is linked to another through hydrogen bond and it undergoes facile decomposition at 300 C to deposit granular copper metal film under nitrogen atmosphere. The decomposition temperature, thermal behaviour, kinetic parameters, evolved gas pattern of the complex, morphology, and the composition of the film were also investigated.

• Bulletin of the Korean Chemical Society
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• 제23권9호
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• pp.1213-1221
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• 2002

Friedel-Crafts alkylation reaction of an isomeric mixture of 1,2,3,4,5,6,7,8- (2) and 1,2,3,4,5,6,7,8-octahydrophenanthrene (2') with excess vinylchlorosilanes such as vinyl(methyl)dichlorosilane (1a) and vinyltrichlorosilane (1b) in the presence of aluminum chloride catalyst at 80 $^{\circ}C$ gives only one dialkylated products, 9,10-bis[2-(chlorosilyl)ethyl]-1,2,3,4,5,6,7,8-octahydroanthrenes [(Cl2XSiCH2CH2)2C14H16: X = Me (4a), Cl (4b)] in good yields, but 9,10-bis[2-(chlorosilyl)ethyl]-1,2,3,4,5,6,7,8-octahydrophenanthrenes are not obtained. However, monoalkylation of 2 with 1 affords a mixture of both isomeric compounds, 9-[2-(chlorosilyl)ethyl]-1,2,3,4,5,6,7,8-octahydroanthracenes 3 and -phenanthrenes 3'. The yield of product 3' is always higher than that of 3. When a mixture of 3 and 3' is alkylated again with 1, only product 4 without phenanthrene type compounds is obtained, indicating that the isomerizations between 2 and 2', or 3 and 3'occur under the alkylation condition. The alkylation with dimethylvinylchlorosilane or trimethylvinylsilane did not proceed. The structure of 4a is determined by X-ray single crystal diffraction analysis.

• 한국재료학회지
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• 제26권4호
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• pp.222-227
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• 2016

Tin oxides have been studied for various applications such as gas detecting materials, transparent electrodes, transparent devices, and solar cells. p-type SnO is a promising transparent oxide semiconductor because of its high optical transparency and excellent electrical properties. In this study, we fabricated p-type SnO thin film using rf magnetron sputtering with an SnO/Sn composite target; we examined the effects of various oxygen flow rates on the SnO thin films. We fundamentally investigated the structural, optical, and electrical properties of the p-type SnO thin films utilizing X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV/Vis spectrometry, and Hall Effect measurement. A p-type SnO thin film of $P_{O2}=3%$ was obtained with > 80% transmittance, carrier concentration of $1.12{\times}10^{18}cm^{-3}$, and mobility of $1.18cm^2V^{-1}s^{-1}$. With increasing of the oxygen partial pressure, electrical conductivity transition from p-type to n-type was observed in the SnO crystal structure.