• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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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.

• Proceedings of the KIEE Conference
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• 2005.11a
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1539-1542
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• 2005

Self-assembled monolayers (SAMs) formed by the adsorption of alkanethiols, $HS(CH_2)_nX$, where X is an organic functional group, onto gold surfaces have attracted widespread interest as templates for the fabrication of molecular and biomolecular microstructures. Previously photopatterning has been thought of as being restricted to the micron scale, because of the wellknown diffraction limit. So, we have explored a novel approach to nanofabrication by utilizing a femtosecond laser coupled to a near-field scanning optical microscope (NSOM).

• Polymer(Korea)
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• v.29 no.4
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• pp.331-337
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• 2005

In general, alkanethiolates having carboxylic acid in the tail group have been used as biorecepton. In this study, we have immobilized a cytochrome c protein using conjugated aromaticthiolates in order to improve the electrical property and physical stability of alkanethilolates. The pattern formation of self-assembled aromaticthiolate monolayers was as follow. Aromatic thiolates bound on the gold surface by the adsorption of 4'-mercapto-biphenyl-4-carboxylic acid and 4-mercapto-[1,1';4',1']terphenyl-4'-carboxylic acid were oxidized by the irradiation of deep UV light through a negative mask. The negative type pattern of the self-assembled monolayer (SAM) was obtained by developing with a deionized water. The pattern formation and electrical conductivity of aromaticthiolate SAMs was investigated by the measurements of STM and AFM. In addition, cytochrome c or ferrocene amide was immobilized onto the patterned substrate. We also studied on the effect of conjugated aromatic thiolates on the electrical activity of cytochrome c or ferrocene amide by cyclic voltammetry.

• Journal of Integrative Natural Science
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• v.4 no.4
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• pp.311-314
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• 2011

Application of self-assembled monolayers (SAMs) to the fabrication of organic thin film transistor has been recently reported very often since it can help to provide ohmic contact between films as well as to form simple and effective electrode pattern. Accordingly, quality of these ultra-thin films is becoming more imperative. In this study, in order to manufacture a high quality SAM pattern, a hydrophobic alkylsilane monolayer and a hydrophilic aminosilane monolayer were selectively coated on $SiO_2$ surface through the consecutive procedures of a micro-contact printing (${\mu}CP$) and dip-coating methods under extremely dry condition. On a SAM pattern cleaned with SC1 solution immediately after ${\mu}CP$, poly(3,4-ethylenedioxythiophene) (PEDOT) source and drain electrode array were very selectively and nicely vapour phase polymerized. On the other side, on a SC1-untreated SAM pattern, PEDOT array was very poorly polymerized. It strongly suggests that the SC1 cleaning process effectively removes unwanted contaminants on SAM pattern, thereby resulting in very selective growth of PEDOT electrode pattern.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1893-1895
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• 2001

In this paper, novel release technique using wet etch is proposed. The results of this technique and the results of SAMs (Self-Assembled monolayers) coated after release using this technique are compared. Fabricated structure have 100 um in width and experimental length is from 100 um to 1 mm. Thickness of aluminum sacrificial layer is 2 um and structure thickness is 2.5 um. Cantilevers and bridges are fabricated with electroplated gold and silicon nitride deposited on substrate. An aluminium sacrificial layer was evaporated thermally and removed in various wet etching solutions. Detachment length of cantilever is 200 um and detachment length of bridge is 1 mm after isooctane rinsing. And the SAMs coating condition which is appropriate for gold and nitride are studied respectively.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.981-987
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• 2002

Monodispersed colloidal silica was prepared by Stober process. We have synthesized monodispersed colloidal silica of carious sizes (100 nm, 200 nm, 300 nm) by controlling volume ratios of TEOS(Tetraethylorthosilicate), $NH_4OH$, Ethanol and D. I. water. Shape and monodispersity of the synthesized colloidal particles were observed by Scanning Electron Microscopy(SEM) and laser light scattering particle analyzer. Self-assembled monolayer of monodispersed colloids was achieved by dipping Si substrate into a well-dispersed silica suspension. It was determined that uniformity and spatial extent of the self-assemble monolayer of monodispersed colloids are significantly influenced by the experimental parameters such as concentration, pH and surface tension of the colloidal suspension. We have observed a hexagonally well-ordered packing colloidal monolayer in a relatively large area (1.5 mm ${\times}$ 1.5 mm) as confirmed by SEM.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1582-1584
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• 2008

This paper reports a simple fabrication method for creating the superhydrophobic polymer surface using a plasma etching. Generally, it is necessary for the superhydrophobic surfaces to have a rough structure on surface with the composition of the low surface energy. In this study, Poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET), acrylonitrile butadiene styrene (ABS) with superhydrophobic surface were fabricated using $O_2$ plasma etching and vapor deposition with the fluoroalkylsilane self-assembled monolayers. The plasma treated polymer surfaces are covered with the nano-pillar shaped structures after treatment for $1{\sim}2min$. And these samples with FOTS SAMs coating are showed the superhydrophobicity having the water contact angle of around $150^{\circ}$ and sometimes around $180^{\circ}$ depending on the treatment time. Furthermore the nanostructured polymer is transparent for the visible light.

• Journal of Adhesion and Interface
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• v.24 no.2
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• pp.64-68
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• 2023

Organic field-effect transistors (OFETs) are attracting attention in the field of next-generation electronic devices, and they can be fabricated on a flexible substrate using an organic semiconductor as a channel layer. In particular, DPP-based semiconducting conjugated polymers are actively used because they have higher charge carrier mobility than other organic semiconductors, but they are still lower than inorganic semiconductors, so various studies are being conducted to improve the charge carrier mobility. In this study, the charge carrier mobility is improved by controlling the surface energy of the substrate by forming self-assembled monolayers (SAMs). As the surface energy of the substrate is controlled by the SAMs, the crystallinity increases, thereby improving the charge carrier mobility by 14 times from 3.57×10^-3 cm²V^-1s^-1 to 5.12×10^-2 cm²V^-1s^-1

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.91-92
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• 2006

The electrical properties of viologen derivatives were studied in terms of the tunneling current characteristics on the length of the viologen derivatives using self-assembling techniques and ultra high vacuum scanning tunneling microscopy (UHV-STM). We fabricated the Au substrate were deposited by thermal evaporation system ($420^{\circ}C$. Self-assembled monolayers (SAMs) were prepared on Au (111), which had been thermally deposited onto freshly cleaved, heated mica. The Au substrate was exposed to a 1 mM solution of viologen derivatives in ethanol for 24 hours to form a monolayer. We measurement of the morphology on the single viologen molecules ($VC_{8}SH$, $VC_{10}SH$, $HSC_{8}VC_{8}SH$, and $HSC_{10}VC_{10}SH$). The current-voltage (I-V) and differential conductance (dl/dV-V) properties were measured while the electrical properties of the formed monolayer were scanned by using a STS. The effective barrier height of viologen derivatives ($VC_{8}SH$, $VC_{10}SH$, $HSC_{8}VC_{8}SH$, and $HSC_{10}VC_{10}SH$) were calculated to be 1.076 eV, 1.56 ${\pm}$ 0.3 eV, 1.85 eV, 2.28 eV, respectively.