• Applied Science and Convergence Technology
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• 제26권4호
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• pp.55-61
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• 2017

Graphene, with a carrier mobility achieving up to $140,000cm^2/Vs$ at room temperature, makes it an ideal material for application in semiconductor devices. However, when the metal comes in contact with the graphene sheet, an energy barrier forms at the metal-graphene interface, resulting in a drastic reduction of the carrier mobility of graphene. In this review, the various methods of forming metal-graphene covalent contacts to lower the contact resistance are discussed. Furthermore, the graphene sheet in the area of metal contact can be cut in certain patterns, also discussed in this review, which provides a more efficient approach to forming covalent contacts, ultimately reducing the contact resistance for the realization of high-performance graphene devices.

• 한국진공학회지
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• 제15권5호
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• pp.485-492
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• 2006

새로운 1가 구리 전구체인 $[Cu^I(hfac)]_2(DVTMSO)$ and $[Cu^I(hfac)]_2(HD)$ (hfac=hexa- fluoroacetylacetonate, DVTMSO=1,2-divinyltetramethyldisiloxane, HD=1,5-hexadiene)를 합성하였으며, 또한 유기금속 화학증착법을 사용하여 증착특성을 확인하였다. 새로운 전구체는 기존 구리 1가 전구체와는 다르게 두 개의 Cu(hfac)가 하나의 중성리간드에 결합된 형태를 가지고 있다. 또한 새롭게 합성된 두 종류의 전구체는 기존에 알려진 1가 구리 고체 전구체에 비해 높은 안정성 및 높은 증기압을 가지고 있는 것이 확인하였다. 아울러 기존의 전구체와는 달리 새로운 전구체로 화학증착하면 막 (films)을 형성하지 않고 구리점 (dots)을 형성하는 것을 확인하였으며 이는 새로운 구조로부터 기인된 현상이라고 생각된다. 구리점의 모양은 증착온도에 따라 급격하게 변하는 것도 관찰되었다.

• 자원리싸이클링
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• 제19권5호
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• pp.31-43
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• 2010

석탄가스화 복합발전 시스템의 집진설비용 다공성 탄화수소 캔들 필터 제조를 위해 래밍성형과 진공 압출성형 공정에 외해 캔들필터 성형체를 제조하였다. 다양한 입도를 갖는 탄화규소 분말을 출발원료로 하였으며, 비점토계 무기 소결조제로 뮬라이트와 칼슘 카보네이트 분말을 사용하였다. 래밍성형과 진공 압출성형에 의한 캔들 필터 성형체들은 대기 분위기 $1400^{\circ}C$에서 2시간 소성하여 제조하였다. 캔들 필터 성형공정과 출발원료 입도가 소결된 다공성 캔들 필터 지지층의 기공율, 밀도, 강도 (굽힘강도, 압축강도)와 미세구조에 미치는 영향을 조사하였다. 래밍성형 공정에 외한 제조원 다공성 탄화규소 캔들 필터 소결체가 압출성형된 필터에 비해 높은 밀도 및 강도를 나타내고 있었으며, 그 최고 값은 각각 $2.0\;g/cm^3$과 45 MPa이었다. 한편 캔들 필터 지지층의 장기 내식성 평가 예측을 위하여 소결된 시편에 대해 석탄가스화 복합발전 $600^{\circ}C$의 모사 합성가스 분위기에서 2400시간 부식실험을 수행하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.229-229
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• 2012

Adhesion of Copper film on the aluminum oxide layer formed by anodizing an aluminum plate was enhanced by applying ion beam mixing method. Forming an conductive metal layer on the insulating oxide surface without using adhesive epoxy bonds provide metal-PCB(Printed Circuit Board) better thermal conductivities, which are crucial for high power electric device working condition. IBM (Ion beam mixing) process consists of 3 steps; a preliminary deposition of an film, ion beam bombardment, and additional deposition of film with a proper thickness for the application. For the deposition of the films, e-beam evaporation method was used and 70 KeV N-ions were applied for the ion beam bombardment in this work. Adhesions of the interfaces measured by the adhesive tape test and the pull-off test showed an enhancement with the aid of IBM and the adhesion of the ion-beam-mixed films were commercially acceptable. The mixing feature of the atoms near the interface was studied by scanning electron microscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy.

• 소성∙가공
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• 제18권3호
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• pp.217-222
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• 2009

Automobile industries have been focusing their efforts on the development of exhaust manifolds using high temperature stainless steels. Exhaust manifolds fabricated with stainless steels can be categorized into tubular and cast ones. The former is usually manufactured by forming and welding process and the latter by vacuum casting process. In the present study, high temperature mechanical properties of 5 austenitic and 4 ferritic stainless steels were investigated by performing a series of high temperature tensile and low cycle fatigue tests. One of the austenitic stainless steels was vacuum cast and the others sand cast. Fatigue life of ferritic stainless steels was higher than that of austenitic ones.

• Journal of Korean Vacuum Science & Technology
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• 제3권1호
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• pp.24-29
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• 1999

The characteristic behaviors of CH3Br were examined first for the dry etching of polysilicon in a Cl2/CH3Br/O2 plasma. CH3Br is revealed one of the excellent additive gases to control anisotropy of etching profile and to give no undercutting for various typed of polysilicons. CH3Br acts as a passivation precursor on the side wall in etch cavity by forming polymer-like films such as CHxBry(x+y=1,2). The decrease of etch selectivity due to the reaction if the C-containing species from CH3Br with the surface O atoms of SiO2 was overcome by the addition of O2 into plasma, resulting that the selectivity increased by 2~3 times. According to the results of optical emission signals, CH3Br should be dissociated into several fragments to give more hydrogen atoms than bromine atoms in our helical resonator system.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2008년도 제34회 동계학술대회 초록집
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• pp.343-343
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• 2008

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.314-317
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• 2007

Domestic automobile industries have been focusing their effort on development of exhaust manifolds using high temperature stainless steel. Exhaust manifolds fabricated with stainless steels can be categorized into tubular and cast ones. The former is usually manufactured by forming and welding process and the latter by vacuum casting process. In the present study, high temperature mechanical properties of 5 austenitic stainless steels, one was sand cast and the others vacuum cast, were investigated by performing a series of high temperature tensile tests and high temperature low cycle fatigue tests.

• 한국진공학회지
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• 제12권S1호
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• pp.21-27
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• 2003

Micro-arc discharge oxidation (MDO) is a cost-effective plasma electrolytic process which can be used to improve the wear and corrosion resistance of Al-alloy parts by forming a alumina coating on the component surface. However, the MDO coated Al-alloy components often exhibit relatively high friction coefficients and low wear resistance fitted with many counterface materials, additionally, the pitting corrosion for the MDO coated AI-alloy components, especially for a thinner alumina coating, often occurs in atmosphere circumstance due to the porous alumina coats. Therefore, a duplex treatment, combining a MDO coated ahumina thin layer with a TiN coating, prepared by magnetron sputtering (MS), has been investigated. The Vicker's microhardness, pin-on-disc, electrochemical measurement, salt spray, XRD and SEM tests were used to characterize and analyze the treated samples. The work demonstrates that the MDO/MS coated samples have a combination of a very low friction coefficient and good wear resistance as well as corrosion since the micro-holes on alumina coating are partly or fully covered by TiN material.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.151-151
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• 2000

We have studied the atomic structure of Si(100)-c(4$\times$4) reconstruction using scanning tunneling microscopy(STM). The c(4$\times$4) reconstruction can be formed by annealing the hydrogen exposured surface at temperatures between 850 and 960 K. At this temperature ranges, adsorbed hydrogen atoms are all desorbed. Therefore, the c(4$\times$4) reconstruction is due to the Si dimers on surface. The filled and empty state images of the STM were interpreted in terms of Si dimers in c(4$\times$4) primitive cell forming the reconstruction. Based on the STM images and hydrogen adsorption experiment on c(4$\times$40 surface, we suggest that Si dimers in c(4$\times$40 unit cell are perpendicular ad-dimer to the underlying Si dimer rows.