• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.452-455
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• 2004

In this paper, investigations of the SAMs(self-assembled monolayers) of a thiol-fuctionalized viologen derivatives, $V_8SH$ and $SH_8V_8SH$, where, V is N,N'-dialkylbipyridinium (i.e. a viologen group), have been carried out by elucidate voltammetry date. The redox reactions are highly reversible and can be cycled many times without significant side reaction, which has been known as a nano-gram order mass detector through resonant frequency change self-assembly process of the viologen has been investigated with $QCM({\Delta}F)$. The assembling process of the $V_8SH$ and $SH_8V_8SH$ monolayers can be finished completely in about 1 hour. The measured frequency shift for $V_8SH$ and $SH_8V_8SH$ were about 351 and 172 Hz, respectively. From these values, we calculated that the mass adsorbed $V_8SH$ and $SH_8V_8SH$ were about 375 and 183 ng. We believe that this mass loss is caused by the simultaneous loss of the anions present within the monolayer for charge compensation of the viologen dications and some solvent.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.139-141
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• 2005

It is possble to study charge transfer property which is caused by height variation because we can see the organic materials barrier height and STM tip by organic materials energy band gap. Here, we investigated the negative differential resistance(NDR) and charge transfer property of self-assembled 4,4-Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene, which has been well known as a conducting molecule. Self-assembly monolayers(SAMs) were prepared on Au(111), which had been thermally deposited onto pre-treatment($H_{2}SO_{4}:H_{2}O_{2}$=3:1) Si. The Au substrate was exposed to a 1 mM/l solution of 1-dodecanethiol in ethanol for 24 hours to form a monolayer. After thorough rinsing the sample, it was exposed to a $0.1{\mu}M/1$ solution of 4,4-Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene in dimethylformamide(DMF) for 30 min and kept in the dark during immersion to avoid photo-oxidation. After the assembly, the samples were removed from the solutions, rinsed thoroughly with methanol, acetone, and $CH_{2}Cl_{2}$, and finally blown dry with $N_2$. Under these conditions, we measured electrical properties of self-assembly monolayers(SAMs) using ultra high vacuum scanning tunneling microscopy(UHV-STM). The applied voltages were from -1.50 V to -1.20 V with 298 K temperature. The vacuum condition is $6{\times}10^{-8}$ Torr. As a result, we found that NDR and charge transfer property by a little change of height when the voltage is applied between STM tip and electrode.

• 폴리머
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• 제29권3호
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• pp.308-313
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• 2005

광감응성 azobenzene 그룹이 분자의 주위 환경에 따라 광이성화 반응이 변화하는 것을 in-situ UV/Vis 분광 실험법과 광학 이방성 측정법을 이용하여 조사하였다. 4-Hyhoxyazobenzene을 포함하는 필름에 광조사함과 동시에 trans-isomer와 cis-isomer 특성 피크의 세기 변화를 측정하여 azobenzene 그룹의 가역적이며 반복적인 광이성화 반응을 알수 있었다. Azobenzene 자기조립체 박막이 입혀진 기판을 액정 셀의 배향막으로 사용하여 액정의 배향을 유도하였을 때, trans-azobenzene 그룹들이 조밀한 packing을 하며 기판에 수직으로 배열한 자기조립체 구조 때문에 액정 분자들도 수직 homeotropic 배향을 하였다. 이와 같은 자기조립체 박막의 액정 셀에 UV 빛을 노광하면 azobenzene그룹이 광이 성화 반응을 일으켜 cis-isomer로 변하게 되며, 이로 인해 액정의 배향이 수직에서 수평 planar 배향으로 변함을 알 수있었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.22.2-22.2
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• 2009

Currently, metal silicides become increasingly more essential part as a contact material in complimentary metal-oxide-semiconductor (CMOS). Among various silicides, NiSi has several advantages such as low resistivity against narrow line width and low Si consumption. Generally, metal silicides are formed through physical vapor deposition (PVD) of metal film, followed by annealing. Nanoscale devices require formation of contact in the inside of deep contact holes, especially for memory device. However, PVD may suffer from poor conformality in deep contact holes. Therefore, Atomic layer deposition (ALD) can be a promising method since it can produce thin films with excellent conformality and atomic scale thickness controllability through the self-saturated surface reaction. In this study, Ni thin films were deposited by thermal ALD using bis(dimethylamino-2-methyl-2-butoxo)nickel [Ni(dmamb)2] as a precursor and NH3 gas as a reactant. The Ni ALD produced pure metallic Ni films with low resistivity of 25 $\mu{\Omega}cm$. In addition, it showed the excellent conformality in nanoscale contact holes as well as on Si nanowires. Meanwhile, the Ni ALD was applied to area-selective ALD using octadecyltrichlorosilane (OTS) self-assembled monolayer as a blocking layer. Due to the differences of the nucleation on OTS modified surfaces toward ALD reaction, ALD Ni films were selectively deposited on un-coated OTS region, producing 3 ${\mu}m$-width Ni line patterns without expensive patterning process.

• 한국정보전자통신기술학회논문지
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• 제8권1호
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• pp.37-44
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• 2015

본 논문에서 전계효과 트랜지스터 (field effect transistor; FET) 제작을 위한 표면 프로그램된 aminopropylethoxysilane(APTES)와 1-octadecyltrichlorosilane(OTS) 패턴을 이용하여 단일벽 탄소 나노튜브(single-walled carbon nanotube; SWCNT)를 실리콘 기판 위에 선택적으로 흡착시키는 공정방법을 제안하였다. 양성 표면 분자 패턴을 만들기 위해 형성된 APTES 패턴은 많은 양의 SWCNT의 흡착을 위해 제작되었고, OTS 만을 이용한 공정보다 효과적인 SWCNT 흡착이 가능하다. 산화막(silicon dioxide)이 형성된 실리콘 기판 위에 사진공정(photolithography process)을 이용하여 임의의 감광액(photoresist; PR) 패턴이 형성되었다. PR 패턴이 형성된 기판은 헥산 용매를 이용하여 1:500 (v/v)로 희석된 OTS 용액 속에 담가진다. OTS 박막이 표면 전체에 만들어지고, PR 패턴이 제거되는 과정에서 PR 위에 형성되었던 OTS 박막도 같이 제거되어, 선택적으로 형성된 OTS 박막 패턴을 얻을 수 있다. 이 기판은 다시 에탄올 용매를 이용하여 희석된 APTES 용액 속에 담가진다. APTES 박막은 OTS 박막 패턴이 없는 노출된 산화막 위에 형성된다. 마지막으로 이처럼 APTES와 OTS에 의해 표면 프로그램된 기판은 SWCNT가 분산된 다이클로로벤젠(dichlorobenzene) 용액 속에 담가진다. 결과적으로 SWCNT는 양 극성을 띠는(positive charged) APTES 박막 패턴 위에만 흡착된다. 반면 중성O TS 박막 패턴 위에는흡착되지 않는다. 이러한 표면 프로그램 방법을 사용하여 SWCNT는 원하는 영역에 자기 조립시킬 수 있다. 우리는 이 방법을 이용하여 소오스와 드레인 전극사이에 SWCNT가 멀티 채널로 구성된 다중채널 FET를 성공적으로 제작하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.393-393
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• 2012

Optically active nanostructures such as subwavelength moth-eye antireflective structures or surface enhanced Raman spectroscopy (SERS) active structures have been demonstrated to provide the effective suppression of unwanted reflections as in subwavelength structure (SWS) or effective enhancement of selective signals as in SERS. While various nanopatterning techniques such as photolithography, electron-beam lithography, wafer level nanoimprinting lithography, and interference lithography can be employed to fabricate these nanostructures, roll-to-roll (R2R) nanoimprinting is gaining interests due to its low cost, continuous, and scalable process. R2R nanoimprinting requires a master to produce a stamp that can be wrapped around a quartz roller for repeated nanoimprinting process. Among many possibilities, two different types of mask can be employed to fabricate optically active nanostructures. One is self-assembled Au nanoparticles on Si substrate by depositing Au film with sputtering followed by annealing process. The other is monolayer silica particles dissolved in ethanol spread on the wafer by spin-coating method. The process is optimized by considering the density of Au and silica nano particles, depth and shape of the patterns. The depth of the pattern can be controlled with dry etch process using reactive ion etching (RIE) with the mixture of SF6 and CHF3. The resultant nanostructures are characterized for their reflectance using UV-Vis-NIR spectrophotometer (Agilent technology, Cary 5000) and for surface morphology using scanning electron microscope (SEM, JEOL JSM-7100F). Once optimized, these optically active nanostructures can be used to replicate with roll-to-roll process or soft lithography for various applications including displays, solar cells, and biosensors.

• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.672-678
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• 2006

A new approach to fabricate an enzyme electrode was described based on the immobilization of horseradish peroxidase (HRP) on dithiobis-N-succinimidyl propionate (DTSP) self-assembled monolayer (SAM) formed on gold-nanoparticles (Au-NPs) which were electrochemically deposited onto glassy carbon electrode (GCE) surface. The overall surface area and average size of Au-NPs could be controlled by varying deposition time and were examined by Field Emission-Scanning Electron Microscope (FE-SEM). The $O_2$ reduction capability of the surface demonstrated that Au-NPs were thermodynamically stable enough to stay on GCE surface. The immobilized HRP electrode based on Au-NPs/GCE presented faster, more stable and sensitive amperometric response in the reduction of hydrogen peroxide than a HRP immobilized on DTSP/gold plate electrode not containing Au-NPs. The effects of operating potential, mediator concentration, and pH of buffer electrolyte solution on the performance of the HRP biosensor were investigated. In the optimized experimental conditions, the HRP immobilized GCE incorporating smaller-sized Au-NPs showed higher electrocatalytic activity due to the high surface area to volume ratio of Au-NPs in the biosensor. The HRP electrode showed a linear response to $H_2O_2$ in the concentration range of 1.4 $\mu$M-3.1 mM. The apparent Michaelis-Menten constant ($K _M\; ^{app}$) determined for the immobilized HRP electrodes showed a trend to be decreased by decreasing size of Au-NPs electrodeposited onto GCE.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.74-78
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• 2003

본 논문에서는 금속의 표면 플라즈몬 공명으로 인한 금속-유전체 경계면에서의 국소적 전자기장의 강화 효과를 이용하여 표면 플라즈몬을 유발하는 금 박막을 유리 기판위에 증착하고, 프리즘 커플러를 이용한 소산장의 공명 흡수현상을 이차원 영상 으로 얻었다. 특히 DNA/단백질 칩 등 향후 가능한 다채널 시스템에의 응용을 고려하여11-MUA, 11-MUOH 등 자기조립 단분자막(SAM)을 크롬 마스크와 리토그래피, 그리고 Shadow mask와 광 산화반응을 이용하여 금 표면 위에 패터닝 하였다. 텅스텐-할로겐 램프와 중심파장이 ${\lambda}_0=633$ nm의 대역통과 필터를 사용하여 이 평행광을 프리즘 커플러에 입사시켜 반사되어 나오는 반사광의 이차원 영상을 얻었다. 이와는 별도로 ${\lambda}_0=633$ nm의 레이저를 이용하여 단분자막이 코팅되어 있을 때와 없을 때의 공명각의 변화를 관찰하였다. 얻어진 이차원 영상의 위치에 따른 화소 값의 변화를 단분자 막의 두께의 변화에 따라 보정하고, 알려진 매질의 SPR 특성을 Fresnel 방정식에 따라 이론적으로 계산하면 다채널 표면 영상으로부터 항원-항체 등 단백질의 결합 정도를 정량적으로 측정할 수 있다.

• 센서학회지
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• 제15권3호
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• pp.192-198
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• 2006

In this study, the light addressable potentiometric sensors (LAPS) with $Si_{3}N_{4}/SiO_{2}/Si$, and $Ta_{2}O_{5}/SiO_{2}/Si$ structures were fabricated. The penicillinsae was immobilized on the devices to hydrolyze the penicillin using self-assembled monolayer (SAM) method. Then response characteristics according to the penicillin concentrations were measured and compared. The measuring system was simplified by using LabVIEW. The pH response characteristics of fabricated devices are 56 mV/pH ($Si_{3}N_{4}$ sensing membrane) and 61 mV/pH ($Ta_{2}O_{5}$ sensing membrane). The sensitivity of sensor by enzyme reaction result of the enzyme reaction were 60 mV/decade and 74 mV/decade for $Si_{3}N_{4}/SiO_{2}/Si$ and $Ta_{2}O_{5}/SiO_{2}/Si$ structure, respectively, in the range of $0.1\;mM{\sim}10\;mM $of the penicillin concentration.

• Progress in Superconductivity
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• 제11권1호
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• pp.47-51
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• 2009

For many large-scale applications of high-temperature superconducting materials, large critical current density ($J_c$) in high applied magnetic fields are required. A number of methods have been reported to introduce artificial pinning centers in $YBa_2Cu_3O_{7-{\delta}}$ films for enhancement of their $J_c$. We studied the microstructures and characteristic of $YBa_2Cu_3O_{7-{\delta}}$ films fabricated on $SrTiO_3$ (100) substrates with ZnO nanorods as pinning centers. Au catalyst nanoparticles were synthesized on STO substrates with self assembled monolayer to control the number of ZnO nanorods. The density of Au nanoparticles is approximately $240{\sim}260{\mu}m^{-2}$ with diameters of $41{\sim}49nm$. ZnO nanorods were grown on STO by hot-walled PLD with Au nanoparticles. Typical size of ZnO nanorod was around 179 nm in diameter and $2{\sim}6{\mu}m$ in length respectively. YBCO films deposited directly on STO substrates show the c-axis orientation, while YBCO films with ZnO nanorods exhibit any mixed phases without any typical crystal orientation.