• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.632-632
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• 2013

We generated single-crystal organic nanowire arrays using a direct printing method (liquidbridge- mediated nanotransfer molding) that enables the simultaneous synthesis, alignment and patterning of nanowires from molecular ink solutions. Using this method, single-crystal organic nanowires can easily be synthesized by self-assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. The position of the nanowires on complex structures is easy to adjust, because the mold is movable on the substrates before the polar liquid layer, which acts as an adhesive lubricant, is dried. Repeated application of the direct printing process can be used to produce organic nanowire-integrated electronics with twoor three-dimensional complex structures on large-area flexible substrates. This efficient manufacturing method is used to fabricate all-organic nanowire field-effect transistors that are integrated into device arrays and inverters on flexible plastic substrates.

• Journal of Electrical Engineering and Technology
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• v.7 no.3
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• pp.396-400
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• 2012

Novel fabrication method of nanobridge array of various materials was proposed using suspended silicon nanowire array as a sacrificial template structure. Nanobridges of various materials can be simply fabricated by direct deposition with thermal evaporation on the top of prefabricated suspended silicon nanobridge arrays, which are used as a sacrificial structure. Since silicon nanowire can be easily removed by selective dry etching, nanobridge arrays of an intended material are finally obtained. In this paper, metal nanobridges of Ti/Au, around 50-200 nm in thickness and width, 5-20 ${\mu}m$ in length were fabricated to prove the advantages of the proposed nanowire or nanobridge fabrication method. The nanobridges of Ti/Au after complete removal of sacrificial silicon nanowire template were well-established and bending of nanobridge caused by the tensile stress was observed after silicon removing. Up to 50 nm and 10 ${\mu}m$ of silicon nanowire in diameter and length respectively was also very useful for nanowire templates.

• Journal of Integrative Natural Science
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• v.5 no.4
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• pp.211-215
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• 2012

Single-crystalline silicon nanowire arrays (SiNWAs) using electroless metal-assisted etchings of p-type silicon were successfully fabricated. Ag nanoparticle deposition on silicon wafers in HF solution acted as a localized micro-electrochemical redox reaction process in which both anodic and cathodic process took place simultaneously at the silicon surface to give SiNWAs. The growth effect of SiNWs was investigated by changing of etching times. The morphologies of SiNWAs were obtained by SEM observation. Well-aligned nanowire arrays perpendicular to the surface of the silicon substrate were produced. Optical characteristics of SiNWs were measured by FT-IR spectroscopy and indicated that the surface of SiNWs are terminated with hydrogen. The thicknesses and lengths of SiNWs are typically 150-250 nm and 2 to 5 microns, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.560-560
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• 2012

We report a one-step fabrication method of Poly(9,9-dioctylfluorene) (PFO) nanowire array with pronounced ${\beta}$-Phase. We use liquid-bridge-mediated nanotransfer molding (LB-nTM) which is a new direct nano-patterning method based on the direct transfer of various materials from a mold to a substrate via liquid layer. The formation of the ${\beta}$-phase morphology in the resulting PFO nanowire array was evidenced by the presence of an absorption peak at 435nm. With the collection polarizer oriented parallel to the wire long axis, the PL emission was most intense and an emission dichroic ratio, DRE, of 3.7 was determined. The nanowire array have been investigated by scanning electron microscopy (SEM). Also, we simply fabricated structure of device of ITO/PFO nanowire arrays/Al and the electroluminescence spectra were recorded at various applied voltage.

• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1341-1345
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• 2004

We developed a novel synthesis strategy of titania nanowire arrays by employing simple hydrothermal reaction and ion-exchange reaction techniques. Hydrothermal reactions of metallic titanium powder with $H_2O_2$ in a 10 M NaOH solution produced a new sodium titanate compound, $Na_2Ti_6O_{13}{\cdot}xH_2O$ (x~4.2), as arrays of nanowires of lengths up to 1 mm. Acid-treatment followed by calcination of this material produced arrays of highly crystalline anatase nanowires as evidenced by x-ray diffraction, Raman spectroscopy, and transmission electron microscopy studies. In both cases of sodium titanate and anatase, the nanowires have exceptionally large aspect ratios of 10,000 or higher, and they form arrays over a large area of $1.5 {\times} 3 cm^2$. Observations on the reaction products with varied conditions indicate that the array formation requires simultaneously controlled formation and crystal growth rates of the $Na_2Ti_6O_{13}{\cdot}xH_2O$ phase.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.57-60
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• 2001

We prepared uniform CdS nanowire arrays ways with lengths up to 5 $\mu\textrm{m}$ and diameters as small as 20 nm by electrochemically depositing the semiconductor directly into the pores of anodic alumina films from an electrolyte containing $CdCl_2$ and S in dimethyl sulfoxide. The nanowire arrays were characterized by scanning electron microscopy and X-ray diffraction. The deposited materials are composed mainly of hexagonal CdS with (100) preferential orientation.

• Journal of Powder Materials
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• v.22 no.3
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• pp.216-220
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• 2015

Vertically oriented nickel nanowire arrays with a different diameter and length are synthesized in porous anodic aluminium oxide templates by an electrodeposition method. The pore diameters of the templates are adjusted by controlling the anodization conditions and then they are utilized as templates to grow nickel nanowire arrays. The nickel nanowires have the average diameters of approximately 25 and 260 nm and the crystal structure, morphology and microstructure of the nanowires are systematically investigated using XRD, FE-SEM and TEM analysis. The nickel nanowire arrays show a magnetic anisotropy with the easy axis parallel to the nanowires and the coercivity and remanence enhance with decreasing a wire diameter and increasing a wire length.

• Korean Journal of Materials Research
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• v.20 no.1
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• pp.25-30
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• 2010

Si nanowire/multiwalled carbon nanotube nanocomposite arrays were synthesized. Vertically aligned Si nanowire arrays were fabricated by Ag nanodendrite-assisted wet chemical etching of n-type wafers using $HF/AgNO_3$ solution. The composite structure was synthesized by formation of a sheath of carbon multilayers on a Si nanowire template surface through a thermal CVD process under various conditions. The results of Raman spectroscopy, scanning electron microscopy, and high resolution transmission electron microcopy demonstrate that the obtained nanocomposite has a Si nanowire core/carbon nanotube shell structure. The remarkable feature of the proposed method is that the vertically aligned Si nanowire was encapsulated with a multiwalled carbon nanotube without metal catalysts, which is important for nanodevice fabrication. It can be expected that the introduction of Si nanowires into multiwalled carbon nanotubes may significantly alter their electronic and mechanical properties, and may even result in some unexpected material properties. The proposed method possesses great potential for fabricating other semiconductor/CNT nanocomposites.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.90.2-90.2
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• 2013

Vertically-aligned silicon nanostructure arrays (SNAs) have been drawing much attention due to their useful electrical properties, large surface area, and quantum confinement effect. SNAs are typically fabricated by chemical vapor deposition, reactive ion etching, or wet chemical etching. Recently, metal-assisted chemical etching process, which is relatively simple and cost-effective, in combination with nanosphere lithography was recently demonstrated for vertical SNA fabrication with controlled SNA diameters, lengths, and densities. However, this method exhibits limitations in terms of large-area preparation of unperiodic nanostructures and SNA geometry tuning independent of inter-structure separation. In this work, we introduced the layerby- layer deposition of polyelectrolytes for holding uniformly dispersed polystyrene beads as mask and demonstrated the fabrication of well-dispersed vertical SNAs with controlled geometric parameters on large substrates. Additionally, we present a new means of building in vitro neuronal networks using vertical nanowire arrays. Primary culture of rat hippocampal neurons were deposited on the bare and conducting polymer-coated SNAs and maintained for several weeks while their viability remains for several weeks. Combined with the recently-developed transfection method via nanowire internalization, the patterned vertical nanostructures will contribute to understanding how synaptic connectivity and site-specific perturbation will affect global neuronal network function in an extant in vitro neuronal circuit.

• Transactions on Electrical and Electronic Materials
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• v.7 no.2
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• pp.58-61
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• 2006

Carefully designed ZnO nanowire-film hybrid nanostructure, composed of a bottom ZnO film, ZnO nanowire arrays, and a top ZnO film, was consecutively fabricated by adjusting the supersaturation conditions using a metal-organic chemical vapor deposition (MOCVD) to utilize the vertically aligned ZnO nanowires as the oxygen sensors. The decrease of current flow through ZnO nanowire arrays increasing oxygen pressure showed the high potential for the application of the ZnO hybrid nanostructure to the oxygen sensors. In addition, it was confirmed that the oxygen sensing characteristics of this hybrid nanostructure were attributed to the defects near the surface of the nanowires.