• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.20.1-20.1
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• 2007

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.368-368
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• 2012

We report solution-processed, high-performance single-crystal organic nanowire transistors fabricated from a novel indolocarbazole (IC) derivative. The direct printing process was utilized to generate single-crystal organic nanowire arrays enabling the simultaneous synthesis, alignment and patterning of nanowires using 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. These new molecules are particularly suitable for p-channel organic field-effect transistors (OFETs) because of the high level of crystallinity usually found in IC derivatives. Selected area diffraction (SAED) and X-ray diffraction (XRD) experiments on these solution-processed nanowires showed high crystallinity. Transistors fabricated with these nanowires gave a hole mobility as high as 1.0 cm2V-1s-1 with nanowire arrays with the direct printing process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.178-179
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• 2006

나노 크기를 가지는 DNA 분자를 template로 사용하여 전도성 고분자의 일종인 polypyrrole nanowire를 합성하였다. 본 논문에서 합성된 polypyrrole nanowire는 단량체인 pyrrole과 산화제와의 화학적인 반응에 의해 만들어졌다. 먼저 DNA 분자를 APTES(3-aminopropyltriethoxysilane) modified Si surface 위에 정렬한다. 그리고 이 기판을 농도를 달리한 pyrrole solution에서 incubationn한다. 마지막으로 APS (ammonium persulfate)와 반응시켜 conductive nanowire를 합성하였다. SEM을 이용하여 silicon 기판위에 1차원적으로 정렬된 나노 크기를 가지는 polypyrrole nanowire를 관찰할수 있었다. 그리고 pyrrole의 농도에 따라 nanowire의 uniformity를 조절할 수 있었다.

• Korean Journal of Materials Research
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• v.24 no.10
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• pp.509-514
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• 2014

We demonstrate a simple and effective method to accurately position silicon nanowires (Si NWs) at desirable locations using drop-casting of Si NW inks; this process is suitable for applications in nanoelectronics or nanophotonics. Si NWs were assembled into a lithographically patterned sacrificial photoresist (PR) template by means of capillary interactions at the solution interface. In this process, we varied the type of solvent of the SiNW-containing solution to investigate different assembly behaviors of Si NWs in different solvents. It was found that the assembly of Si NWs was strongly dependent on the surface energy of the solvents, which leads to different evaporation modes of the Si NW solution. After Si NW assembly, the PR template was cleanly removed by thermal decomposition or chemical dissolution and the Si NWs were transferred onto the underlying substrate, preserving its position without any damage. This method enables the precise control necessary to produce highly integrated NW assemblies on all length scales since assembly template is easily fabricated with top-down lithography and removed in a simple process after bottom-up drop-casting of NWs.

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.266.1-266.1
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• 2013

Large-scale single-crystal organic nanowire arrays were generated 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. Repeated application of the direct printing process can be used to produce organic nanowire-integrated electronics with two- or 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 KIISE:Computer Systems and Theory
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• v.37 no.5
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• pp.257-271
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• 2010

As the end of photolithographic integration era is approaching fast, numerous nanoscale devices and systems based on novel nanoscale materials and assembly techniques are recently emerging. Notably, various reconfigurable architectures with considerable promise have been proposed based on nanowire crossbar structure as the primitive building block. Unfortunately, high-density sys-tems consisting of nanometer-scale elements are likely to have numerous physical imperfections and variations. Therefore, defect-tolerance is considered as one of the most exigent challenges in nanowire crossbar systems. In this work, three different defect-avoidant logic mapping algorithms to circumvent defective crosspoints in nanowire reconfigurable crossbar systems are evaluated in terms of various performance metrics. Then, a novel method to find the most cost-effective repair solution is demonstrated by considering all major repair parameters and quantitatively estimating the performance and cost-effectiveness of each algorithm. Extensive parametric simulation results are reported to compare overall repair costs of the repair algorithms under consideration and to validate the cost-driven repair optimization technique.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.2
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• pp.101-105
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• 2006

Nanoscale floating-gate characteristic of colloidal Au nanoparticles electrostatically assembled on the oxidized surface of Si nanowires have been investigated. The Si nanowire split-gate transistor structure was fabricated by electron beam lithography and subsequent reactive ion etching. Colloidal Au nanoparticles with ${\sim}5$ nm diameters were selectively deposited onto the Si nanowire surface by 2 min electrophoresis. It was found that electric fields applied to the self-aligned split side gates allowed charge to be transferred on the Au nanoparticles. It was observed that the depletion mode cutoff voltage, induced by the self-aligned side gates, was shifted by more than 1 V after Au nanoparticle electrophoresis. This may be due to the semi-one dimensional nature of the narrow Si nanowire transport channel, having much enhanced sensitivity to charges on the surface.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.267-267
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• 2013

Band engineering of a nanowire is related to the question what is the minimum size of a nanowire-based device. At the subnanometer scale, there has been a long standing problem whether it is possible to both control an energy band of an isolated nanowire by a dopant and measure it using angle-resolved photoemission spectroscopy (ARPES). This is because an extra atom in the subnanometer wire plays as a defect rather than a dopant and it is challenging to assemble isolated subnanometer wires into an array for an ARPES measurement. We demonstrate that only one of multiple metallic subnanometer wires canbe controlled electronically by a dopant maintaining the whole metallic bands of other wires, which was observed directly by ARPES. Here,the multiple metallic subnanometer wires were produced on a stepped Si(111) surface by a self-assembly method. The selective band engineering proves that the selectively-controlled metallic wire is nearly isolated electronically from other metallic wires and an electronic structure controlcan be realized down to subnanometer scale.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.385-389
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• 2010

This paper presents a microfabricated nanowire diluter which dilutes the concentration of nanowires in solution instead of by the conventional centrifuge process. The device has 16 pairs of gold electrodes in a micro channel composed of a glass substrate and PDMS. We prepared nickel nanowires by the template-directed electrodeposition method using nanoporous anodized aluminum template (AAO). We injected the Dimethylformamide (DMF) solution containing nanowires into the inlet of the diluter while applying square wave voltages on the electrodes to trap the nanowires at the subsequent gold electrodes by means of dielectrophoretic attraction forces. The concentration of nanowires at the outlet of the micro channel was changed as we expected, which illustrates that the device can effectively dilute nanowires and can be applied to a controlled assembly of nanowires.