• 대한기계학회논문집A
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• 제28권9호
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• pp.1270-1275
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• 2004

Standard positive photoresist techniques were adapted to generate nano-scale patterns of gold substrate using self-assembled monolayers (SAMs) and femtosecond laser. SAMs formed by the adsorption of alkanethiols onto gold substrate are employed as very thin photoresists, Alkanethiolates formed by the adsorption of alkanethiols are oxidized on exposure to UV light in the presence of air to alkylsulfonates. Specifically, it is known that deep UV light of wavelength less than 200nm is necessary for oxidation to occur. In this study, ultrafast laser of wavelength 800nm and pulse width 200fs is applied for photolithography. Results show that ultrafast laser of visible range wavelength can replace deep UV laser source for photo patterning using thin organic films. Femtosecond laser coupled near-field scanning optical microscopy facilitates not only the patterning of surface chemical structure, but also the creation of three-dimensional nano-scale structures by combination with suitable etching methods.

• Tribology and Lubricants
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• 제20권2호
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• pp.51-57
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• 2004

Micro/nano adhesion and friction properties of mixed self-assembled monolayer (SAM) with different chain length for MEMS application were experimentally studied. Many kinds of SAM having different spacer chains(C6, C10 and C18) and their mixtures (1:1) were deposited onto Si-wafer, where the deposited SAM resulted in the hydrophobic nature. The adhesion and friction properties between tip and SAM surfaces under nano scale applied load were measured using an atomic force microscope (AFM) and under micro scale applied load were measured using ball-on-flat type micro-tribotester. Surface roughness and water contact angles were measured with SPM (scanning probe microscope) and contact anglemeter. Results showed that water contact angles of mixed SAMs were similar to those of pure SAMs. The morphology of coating surface was roughened as mixing of SAM. Nano adhesion and nano friction decreased as increasing of the spacer chain length and mixing of SAM. Micro friction was decreased as increasing of the spacer chain length, but micro friction of mixed SAM showed the value between pure SAMs. Nano adhesion and friction mechanism of mixed SAM was proposed in a view of stiffness of spacer chain modified chemically and topographically.

• 센서학회지
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• 제13권2호
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• pp.90-95
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• 2004

Protein and gene detection have been growing importance in medical diagnostics. Field effect transistor (FET) - type biosensors have many advantages such as miniaturization, standardization, and mass-production. In this work, we have fabricated metal-oxide-semiconductor (MOS) FET that operates as molecular recognitions based electronic sensor. Measurements were taken with the devices under phosphate buffered saline solution. The drain current ($I_{D}$) was decreased after forming self-assembled mono-layers (SAMs) used to capture the protein, which resulted from the negative charges of SAMs, and increased after forming protein by 11.5% at $V_{G}$ = 0 V due to the positive charges of protein.

• 한국전기전자재료학회논문지
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• 제19권3호
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• pp.246-249
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• 2006

We fabricated self-assembled monolayers(SAMs) onto quartz crystal microbalance(QCM) using viologen, which has been widely used as electron acceptor and electron transfer mediator. We determined the time dependence on resonant frequency shift during self-assembly process and observed the morphology of self-assembled monolayers by STM and investigated the electrochemical behavior of SAMs by cyclic voltammetry. Electrochemical deposition of viologen was investigated using electrochemical quartz crystal microbalance(EQCM). The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redok reactions. The total frequency change was about 9.5 Hz, and 7.1 Hz. From the data, we could know the mass change was about 10.16 ng and 7.60 ng, respectively. Finally, the EQCM has been employed to monitor the electrochemically induced adsorption of self-assembled monolayers on Au surfaces.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.56-63
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• 2003

Micro/nano adhesion and friction properties of mixed self-assembled monolayer (SAM) with different chain length for MEMS application were experimentally studied. Many kinds of SAM having different spacer chains(C6, C10 and C18) and their mixtures (1:1) were deposited onto Si-wafer, where the deposited SAM resulted in the hydrophobic nature. The adhesion and friction properties between tip and SAM surfaces under nano scale applied load were measured using an atomic force microscope (AFM) and micro scale applied load were measured using ball-on-flat type micro-tribotester. Surface roughness and water wetting angles were measured with SPM (scanning probe microscope) and contact anglemeter. Results showed that wetting angles of mixed SAMs showed the similar value of pure SAMs. The coating surface morphology was increased as mixing of SAM. Nano adhesion and nano friction decreased as increasing of the spacer chain length and mixing of SAM. Micro friction was decreased as increasing of the spacer chain, but micro friction of mixed SAM showed the value between pure SAMs. Nano adhesion and friction mechanism of mixed SAM was proposed in a view of stiffness of spacer chain modified chemically and topographically.

• 공업화학
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• 제23권3호
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• pp.289-292
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• 2012

용액공정이 가능한 저분자 유기반도체, triethylsilylethynyl anthradithiophene (TES ADT)을 기반으로 한 유기박막 트랜지스터에서 금 전극의 일함수를 제어하기 위해 표면을 자기조립 단분자막(self-assembled monolayers, SAMs)으로 개질하였다. Benzothiol (BT)과 pentafluorobenzothiol (PFBT) 자기조립 단분자막을 이용해 금 전극의 일함수를 조절하고 이를 통해 TES ADT의 HOMO 준위에 대한 정공주입장벽을 최소화 하고자 하였다. 또한, solvent annealing 후처리 공정을 통해 TES ADT 박막의 결정성을 향상시켰고, 이를 PFBT로 개질된 금 전극을 기반으로 한 유기박막 트랜지스터에 적용한 경우 $0.05\;cm^2/Vs$의 높은 전계효과 이동도와 $10^6$의 높은 점멸비를 보고하였다.

• 공업화학
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• 제16권4호
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• pp.542-548
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• 2005

몇 가지 금속 산화물에 플루오르르 치환된 카르복시산의 자기조립박막을 제조하였다. 사슬 길이의 영향을 비교하기 위하여 퍼플루오르도테칸 산과 퍼플루오르옥타데칸 산을 사용하였다. 사용된 금속 산화물은 알루미나, 탄탈리아, 티타니아, 지르코니아였다. 자기조립박막의 형성은 DRIFT (Diffuse Reflectance Infrared Fourier Transform) 분광법으로 확인하였다. 퍼플루오르탄화수소는 소수성을 가지므로 형성된 자기조립박막도 소수성을 지닐 것으로 예측된다. 형성된 자기조립박막의 DRIFT 스펙트럼의 품질은 금속산화물의 성분 원소뿐만 아니라 분말으 크기에 따라서도 달라졌다.

• Bulletin of the Korean Chemical Society
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• 제30권6호
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• pp.1309-1312
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• 2009

Surface potential and growth processes of hexadecanethiol (HDT) self-assembled monolayers (SAMs) on Au(111) surfaces were examined by Kelvin probe method and scanning tunneling microscopy. It was found that surface potential strongly depends on surface structure of HDT SAMs. The surface potential shift for the striped phase of HDT SAMs chemisorbed on Au(111) surface was +0.45 eV, which was nearly the same as that of the flat-lying hexadecane layer physisorbed on Au(111) surface. This result indicates that the interfacial dipole layer induced by adsorption of alkyl chains is a main contributor to the surface potential change. In the densely-packed HDT monolayer, further change of the surface potential was observed, suggesting that the dipole moment of the alkanethiol molecules is an origin of the surface potential change. These results indicate that the work function of a metal electrode can be modified by controlling the molecular orientation of an adsorbed molecule.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1998년도 제14회 학술발표회 논문개요집
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• pp.141-142
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• 1998

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.55-56
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• 2002

Nanotribological characteristics of hydrophobic surfaces were studied experimentally using an atomic force microscope (AFM). Two kinds of thiolic self-assembled monolayers (SAM) having different spacer chains and their mixture were deposited onto gold-coated mica, where the deposited SAM resulted in the hydrophobic nature. Results showed that the mixed thiolic SAMs resulted in low adhesion and friction in nano-scale contact. It was argued that the water wetting characteristics played a central role on nano-scale adhesion and friction. Also the effect of mixing the thiolic SAMs were discussed on the basis of real area on contact and the stiffness of the SAM layers.