• 한국재료학회지
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• 제20권11호
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• pp.600-605
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• 2010

In order to meet the requirements of faster speed and higher packing density for devices in the field of semiconductor manufacturing, the development of Cu/Low k device material is explored for use in multi-layer interconnection. SiOC(-H) thin films containing alkylgroup are considered the most promising among all the other low k candidate materials for Cu interconnection, which materials are intended to replace conventional Al wiring. Their promising character is due to their thermal and mechanical properties, which are superior to those of organic materials such as porous $SiO_2$, SiOF, polyimides, and poly (arylene ether). SiOC(-H) thin films containing alkylgroup are generally prepared by PECVD method using trimethoxysilane as precursor. Nano voids in the film originating from the sterichindrance of alkylgroup lower the dielectric constant of the film. In this study, methyltriphenylsilane containing bulky substitute was prepared and characterized by using NMR, single-crystal X-ray, GC-MS, GPC, FT-IR and TGA analyses. Solid-state NMR is utilized to investigate the insoluble samples and the chemical shift of $^{29}Si$. X-ray single crystal results confirm that methyltriphenylsilane is composed of one Si molecule, three phenyl rings and one methyl molecule. When methyltriphenylsilane decomposes, it produces radicals such as phenyl, diphenyl, phenylsilane, diphenylsilane, triphenylsilane, etc. From the analytical data, methyltriphenylsilane was found to be very efficient as a CVD or PECVD precursor.

• Bulletin of the Korean Chemical Society
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• 제25권5호
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• pp.639-646
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• 2004

Metal treated activated carbons are prepared using various metals. Adsorption behaviors, morphologies, as well as antibacterial effects of metal treated samples are compared before and after solvent washing. Adsorption isotherms are used to characterize the porous structure of metal treated activated carbons before and after the solvent washing with acetone or ethyl alcohol. From these data, it is noticed that the changes in physicochemical properties of metal treated activated carbons depend on the solvents employed. Similar results are observed from BET data obtained from nitrogen adsorption isotherms. From scanning electron microscopy (SEM) studies, the changes in shape and size of metal particles are observed after the samples are washed with solvents. These changes result in different blocking effects, which, in turn, affect the adsorption behavior of metal treated activated carbons. X-ray diffraction (XRD) patterns of the samples treated with different metals are different each other. High intense sharp peaks attributed to metals are observed from silver treated samples, while the peaks are not observed from copper treated samples. To compare thermodynamic behavior of metal treated activated carbons washed with different type of solvents, differential scanning calorimetric (DSC) analysis is carried out. The analysis shows similar endothermic curves for all of the samples. Finally, antibacterial effects of metal treated activated carbon against Escherichia coli are discussed. Comparing the effects among the metals employed, highest effects are obtained from Cd, while lowest effects are obtained from Cu. Antibacterial activity becomes higher with the increase of the amount of metals treated, Optimum concentrations of metals to treat activated carbons, obtained from a shake flask test, are known to be 0.4, 0.1, and 0.6 moles for Ag, Cd, and Cu, respectively.

• Carbon letters
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• 제6권3호
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• pp.158-165
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• 2005

Room temperature kinetics of degradation of nerve agent simulants and sarin, an actual nerve agent at the surface of different carbon based adsorbent materials such as active carbon grade 80 CTC, modified whetlerite containing 2.0 and 4.0 % NaOH, active carbon with 4.0 % NaOH, active carbon with 10.0 % Cu (II) ethylenediamine and active carbon with 10.0 % Cu (II) 1,1,1,5,5,5-hexafluoroacetylacetonate were studied. The used adsorbent materials were characterized for surface area and micropore volume by $N_2$ BET. For degradation studies solution of simulants of nerve agent such as dimethyl methylphosphonate (DMMP), diethyl chlorophosphate (DEClP), diethyl cyanophosphate (DECnP) and nerve agent, i.e., sarin in chloroform were prepared and used for the uniform adsorption on the adsorbent systems using their incipient volume at room temperature. Degradation kinetics was monitored by GC/FID and was found to be following pseudo first order reaction. Kinetics parameters such as rate constant and half life were calculated. Half life of degradation with modified whetlerite (MWh/NaOH) system having 4.0 % NaOH was found to be 1.5, 7.9, 1206 and 20 minutes for DECnP, DEClP, DMMP and sarin respectively. MWh/NaOH system showed maximum degradation of simulants of nerve agents and sarin to their hydrolysis products. The reaction products were characterized using NMR technique. MWh/NaOH adsorbent was also found to be active against sulphur mustard.

• Current Photovoltaic Research
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• 제8권2호
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• pp.45-49
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• 2020

Molybdenum (Mo) thin films are widely used as back contact in copper indium diselenide (CISe) solar cells. However, despite this, there are only few published studies on the properties of Mo and characteristics of CISe solar cells formed on such Mo substrates. In this studies, we investigated the properties of sputter deposited Mo bilayer, and fabricated non-vacuum CISe solar cells using bilayer Mo substrates. The changes in surface morphology and electrical resistivity were traced by varying the gas pressure during deposition of the bottom Mo layer. In porous surface structure, it was confirmed that the electrical resistivity of Mo bilayer was increased as the amount of oxygen bonded to the Mo atoms increased. The resulting solar cell characteristics vary as the bottom Mo layer deposition pressure, and the maximum solar cell efficiency was achieved when the bottom layer was deposited at 7 mTorr with a thickness of 100 nm and the top layer deposited at 3 mTorr with a thickness of 400 nm.

• 한국재료학회지
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• 제34권9호
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• pp.409-421
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• 2024

Among the products of the electrocatalytic reduction of carbon dioxide (CO₂RR), CO is currently the most valuable product for industrial applications. However, poor stability is a significant obstacle to CO₂RR. Therefore, we synthesized a series of bimetallic organic framework materials containing different ratios of tungsten to copper using a hydrothermal method and used them as precursors. The precursors were then subjected to pyrolysis at 800 ℃ under argon gas, and the M-N bimetallic sites were formed after 2 h. Loose porous structures favorable for electrocatalytic reactions were finally obtained. The material could operate at lower reduction potentials than existing catalysts and obtained higher Faraday efficiencies than comparable catalysts. Of these, the current density of WCu-C/N (W:Cu = 3:1) could be stabilized at 7.9 mA·cm^-2 and the FE of CO reached 94 % at a hydrogen electrode potential of -0.6 V (V vs. RHE). The novel materials made with a two-step process helped to improve the stability and selectivity of the electrocatalytic reduction of CO₂ to CO, which will help to promote the commercial application of this technology.

• 전기화학회지
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• 제2권2호
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• pp.98-105
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• 1999

본 연구에서는 전기장에 의하여 유발되는 자연대류의 영향을 줄이기 위하여 수평 다공성 유체층에 열적 성충화를 유지하여 부력과 유체층의 안정화 효과를 체계적으로 조사하였다. 이를 위하여 수평 다공성 유체층에서 이중확산대류에 의한 물질전달 상관식을 이론적으로 유도하고, 전기화학 실험을 통하여 이론에 의한 모델을 보완하였다. 물질전달 상관식은 다공성 매질층에 대한 유동 방정식으로 Forchheimer모델을 사용하고 미세 난류 모델을 적용하여, 용질 및 열 Darcy-Rayleigh수와 Lewis 수로 유도하였다. 실험에서는 다공성매질에 포화된 황산구리황산용액내의 구리이온을 전기 화학적 방법을 통하여 확산 또는 자연대류에 의한 물질전달 실험을 수행하였다. 이론 및 실험적 해석 결과를 종합하면 다공성 매질 내에서 구리이온의 이중확산대류에 의한 물질전달 상관식은 다음과 같다. $$Sh=\frac{0.03054(Rs_D-LeRa_D)^{1/2}}{1-3.8788(Rs_D-LeRa_D)^{-1/10}}$$ 본 연구의 결과는 실험치와 잘 부합되었으며, 모델식의 원형은 열 및 물질전달계에서 자연대류의 영향을 효과적으로 제어할 수 있는 방안으로 활용될 수 있을 것이다.

• 마이크로전자및패키징학회지
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• 제26권1호
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• pp.9-15
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• 2019

본 연구에서는 3차원 기공구조를 지닌 금속 및 고분자 소재를 이용한 수직 마찰모드의 정전기반 나노발전기(triboelectric nanogenerator, TENG) 제조기술을 소개하고 이에 관한 응용 연구를 수행하였다. 다양한 장점을 지닌 3차원 기공구조를 활용하여 설계된 간단하며 효율적인 나노발전기로, 반복적인 접촉/분리를 통해, 120 V에 이르는 순간 전압특성과 최대 출력 $0.74mW/m^2$을 획득하였다. 실제적인 응용 연구로 48개의 발광소자 구동 실험을 실시하였으며, 저전력 소비 전자소자 장치로의 응용 확장성을 확인하기 위해 회로 구성을 통한 커패시터 축적기능을 확인하였다. 본 연구에서 소개하는 정전기반 에너지 하베스팅 기술은 매우 경제적으로 제조할 수 있는 실용적인 접근방식으로, 반복적으로 가해지는 마찰에 의한 정전력을 효율적으로 획득하여 가까운 미래에 자가발전(self-powered)형 소형 전기소자 구동, 휴대형 전자기기 및 대규모의 전자 발전 장치에 적용 가능할 것으로 기대된다.

• 한국해양학회지:바다
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• 제6권1호
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• pp.13-26
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• 2001

망간각의 조직 및 지화학적 특성과 코발트 연대측정법(Co-chronometry)을 이용하여, 망간각 형성 이후의 서태평양 지역 고해양환경 변화를 파악하기 위하여 마샬제도 배타적 경제수역 내 Lomilik과 Litakpooki 해저산에서 채취된 6개의 망간각을 분석하였다. 망간각은 조직과 지화학적 성분 차이에 의해, 치밀한 조직(층 1), 퇴적물이나 철산화물이 충진되어 있는 다공성 조직(층 2),그리고 탄산염불화 인회석(Carbonate Fluoapatite)이 충진 또는 치환하고 있는 흑색의 균질한 조직(층 3)의 3개 층으로 구분된다. 층 1은 층 2에 비해 Mn, Co, Ni, Mg의 함량이 높고, 층 2는 Fe, Al, Ti, Ba, Cu, Zn의 함량이 높다. 층 3은 Ca, p의 함량이 층 1과 층 2에 비해 현저히 높으며, Mn, Fe, Co, Ni등의 함량은 층 1과 층 2에 비해 낮다. 코발트 연대측정법 결과에 근거할 때, 연구지역의 망간각은 최소 56~31 Ma(초기 에오세${\sim}$올리고세)전에 형성되기 시작한 것으로 추정된다. 층 1과 층 2, 층 2와 층 3의 경계면은 7${\sim}$3 Ma, 26${\sim}$14 Ma정도이다. 층 3은 층 2가 형성되기 이전의 인산화 작용으로 Ca와 P의 함량이 높으며, 미세조직들이 잘 보존되어 있는 것으로 보아 층 3의 철${\cdot}$망간산화물들이 아산화(suboxic)환경에서 재결정되었다고 보기는 힘들다. 또한 층 3에서 Mn에 비해 상대적으로 더 낮은 Co 함량 등을 고려할 때 과거 지질시대동안 Co 공급량이 일정치 않았을 가능성도 있다. 다공성 조직의 층 2는 약 26${\sim}$9 Ma 동안 형성되었다. 공극사이에 유공충을 포함한 생물기원퇴적물이 포함되어 있으며, Ba, Cu, Zn 등 수층 생물과 관련된 원소의 함량이 높은 것으로 보아 층 2는 고에너지환경에서 형성되었음을 시사한다. 또한 층 2에서 Al의 증가는 쇄설기원 물질의 유입에 의한 것으로 추정된다. 플라이오세 이후에 형성된 층 1은 치밀한 조직을 보이며, 형성 이후 속성작용을 받지 않았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1098-1101
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• 1995

NbTi thin films were prepared on Si wafer and Cu substrate by rf magnetron sputtering in the range of sputtering pressure $3{\times}10^{-2}$torr to $3{\times}10^{-4}$torr at room temperature. The influence of sputtering pressure and substrate type on crystallographic orientation and morphology of NbTi thin films was investigated by using X-ray diffraction(XRD) and scanning electron microscopy(SEM), respectively. And the effect of crystallographic orientation and morphology of NbTi film on electromagnetic behaviors was estimated by measuring critical current in various applied magnetic field. The film morphology changed from porous structure consisting of tapered crystallites to densely deposited film decreasing with sputtering pressure. The change of crystallographic orientation with the sputtering pressure and rf power was calculated from the texture coefficient of(002) plane based on XRD patterns. It was found that a change of texture coefficient of(002) plane increased with decreasing sputtering pressure. From observation of critical current in various applied magnetic field, we have identified that the change of critical current abruptly decrease applying with magnetic field and NbTi film produced at high sputtering pressure does not exhibit superconductivity but at low sputtering pressure shows superconductivity.

• 한국산업융합학회 논문집
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• 제21권1호
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• pp.29-36
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• 2018

Low pressure casting process for unidirectional carbon fiber reinforced aluminum (UD-CF/Al) composites which is an infiltration route of molten Al into porous UD-CF preform has been a cost-effective way to obtain metal matrix composites (MMCs) but, easy to cause non-uniform fiber distribution as CF clustering. Such clustered CFs have been a problem to decrease the density and thermal conductivity (TC) of composites, due to the existence of pores in the clustered area. To obtain high thermal performance composites for heat-sink application, the relationship between fiber distribution and porosity has to be clearly investigated. In this study, the CF distribution was evaluated with quantification approach by using two-dimensional spatial distribution method as local number 2-dimension (LN2D) analysis. Note that the CFs distribution in composites sensitively changed by sizes of Cu bridging particles between the CFs added in the UD-CF preform fabrication stage, and influenced on only $LN2D_{var}$ values.