• Journal of Electrochemical Science and Technology
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• v.3 no.3
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• pp.116-122
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• 2012

As an effort to address the chronic capacity fading of Si anodes and thus achieve their robust cycling performance, herein, we develop a unique electrode in which silicon nanoparticles are embedded in the carbon nanotubes network. Utilizing robust contacts between silicon nanoparticles and carbon nanotubes, the composite electrodes exhibit excellent electrochemical performance : 95.5% capacity retention after 140 cycles as well as rate capability such that at the C-rate increase from 0.1C to 1C to 10C, the specific capacities of 850, 698, and 312 mAh/g are obtained, respectively. The present investigation suggests a useful design principle for silicon as well as other high capacity alloying electrodes that undergo large volume expansions during battery operations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.202-205
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• 2002

The photoluminescence (PL) characteristics of the silicon-oxygen(Si-O) superlattice formed by molecular beam epitaxy (MBE) were studied. To confirm the presence of the nanocrystalline Si structure, Raman scattering measurement was performed. The blue shift was observed in the PL peak of the oxygen-annealed sample, compared to the hydrogen-annealed sample, which is due to a contribution of smaller crystallites. Our results determine the right direction for the fabrication of silicon-based optoelectronic and quantum devices as well as for the replacement of silicon-on-insulator (SOI) in high-speed and low-power silicon MOSFET devices in the future.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.4
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• pp.242-245
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• 2021

In this work, we fabricated oxide on an n-type silicon substrate through local anodic oxidation (LAO) using atomic force microscopy (AFM). The resulting oxide thickness was measured and its correlation with load force, scan speed and applied voltage was analyzed. The surface oxide layer was stripped using a buffered oxide etch. Ohmic contacts were created by applying silver paste on the silicon substrate back face. LAO was performed at approximately 70% humidity. The oxide thickness increased with increasing the load force, the voltage, and reducing the scan speed. We confirmed that LAO/AFM can be used to create both lateral and, to some extent, vertical shapes and patterns, as previously shown in the literature.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1073-1077
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• 2003

This study aims to investigate the fabrication process of nano silicon mold using electron beam lithography (EBL) to generate the nanometer level patterns by nano-imprinting technology. the nano-patterned mold including 100mm pattern size has been fabricated by EBL with different doses ranged from 22 to 38 ${\mu}C/cm^2$ on silicon using the conventional polymethylmetharcylate(PMMA) resist. The silicon mold is fabricated with various patterns such as circles, rectangles, crosses, oblique lines and mixed forms, The effect of dosage on pattern density in EBL is discussed based on SEM (Scannning Electron Microscopy) analysis of fabricated molds. The mold surface is modified by hydrophobic fluorocarbon (FC) thin films to avoid the stiction during nano-imprinting process.

• Journal of Powder Materials
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• v.22 no.1
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• pp.15-20
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• 2015

The composite of porous silicon (Si) and amorphous carbon (C) is prepared by pyrolysis of a nano-porous Si + pitch mixture. The nano-porous Si is prepared by mechanical milling of magnesium powder with silicon monoxide (SiO) followed by removal of MgO with hydrochloric acid (etching process). The Brunauer-Emmett-Teller (BET) surface area of porous Si ($64.52m^2g^{-1}$) is much higher than that before etching Si/MgO ($4.28m^2g^{-1}$) which indicates pores are formed in Si after the etching process. Cycling stability is examined for the nano-porous Si + C composite and the result is compared with the composite of nonporous Si + C. The capacity retention of the former composite is 59.6% after 50 charge/discharge cycles while the latter shows only 28.0%. The pores of Si formed after the etching process is believed to accommodate large volumetric change of Si during charging and discharging process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.339-346
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• 2003

Molecular dynamic simulations of nano indentation on single-crystal silicon (100) surface were performed using diamond indentor. Silicon substrate and diamond indentor were modeled diamond structure with Tersoff potential model. Phase transformation of silicon, incipient plastic deformation, change of incident temperature distribution are investigated through the change of potential energy distribution, displacement-load diagram, the change of kinetic energy distribution and displacements of silicon atoms. Phase transformation is highly localized and consists of a high-density region surrounding the tip. Axial load linearly increased according to the indenting depth. Number of atoms with high kinetic energy increased at the interface between substrate and indentor tip.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.268-271
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• 2005

Etch resistance of mask layer on silicon substrate modified by AFM-based Tribo-Nanolithography (TNL) in Aqueous Solution in an aqueous solution was demonstrated. n consists or sequential processes, nano-scratching and wet chemical etching. The simple scratching can form a mask layer on the silicon substrate, which acting as an etching mask. For TNL, a specially designed cantilever with diamond tip, allowing the formation of mask layer on silicon substrate easily by a simple scratching process, has been applied instead of conventional silicon cantilever fur scanning. This study demonstrates how the TNL parameters can affect the etch resistance of mask layer, hence introducing a new process of AFM-based maskless nanolithography in aqueous solution.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.4
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• pp.332-335
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• 2008

PMMA light guiding plate with nano pattern was fabricated by nano imprint lithography method. A silicon mold for electroplating of nickel was fabricated by conventional photolithography process. A nickel stamp for nano imprint lithography was fabricated by electroplating process using silicon mold. The nano imprint lithography was performed on PMMA plate at $140^{\circ}C$ under pressure of 20kN. The nano pattern on PMMA plate was investigated using FE-SEM. It is shown that the patterns were well transferred for several steps and the nano imprint lithography method could be applied for fabricating patterns of light guiding plate.

• KSTLE International Journal
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• v.9 no.1_2
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• pp.10-12
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• 2008

Silicon micro-patterns were fabricated on Si (100) wafers using photolithography and DRIE (Deep Reactive Ion Etching) fabrication techniques. The patterned shapes included micro-pillars and micro-channels. After the fabrication of the patterns, the patterned surfaces were chemically modified by coating Z-DOL (perfluoropolyether, PFPE) thin films. The surfaces were then evaluated for their micro-friction behavior in comparison with those of bare Si (100) flat, Z-DOL coated Si (100) flat and uncoated Si patterns. Experimental results showed that the chemically treated (Z-DOL coated) patterned surfaces exhibited the lowest values of coefficient of friction when compared to the rest of the test materials. The results indicate that a combination of both the topographical and chemical modification is very effective in reducing the friction property. Combined surface treatments such as these could be useful for tribological applications in miniaturized devices such as Micro/Nano-Electro-Mechanical-Systems (MEMS/NEMS).

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1402-1404
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• 2009

The silicon nitride films for gate dielectric were deposited by catalytic chemical vapor deposition at low temperature (${\leq}200^{\circ}C$). The mixture of $SiH_4$, $NH_3$ and $H_2$ was used as source gases. The current-voltage (I-V) and the capacitance-voltage (C-V) characteristics of the films were measured. The breakdown voltage and the flat band voltage shift of samples were improved by increase of the $NH_3$ contents and $H_2$ dilution ratio. The defect states were analyzed by photoluminescence (PL) spectra. As the defect states decreased, the breakdown voltage and the flat band voltage shift increased.