• KSTLE International Journal
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• v.10 no.1_2
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• pp.1-5
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• 2009

This paper reports an investigation on nanotribological properties of silicon nanochannels coated by a diamond-like carbon (DLC) film. The nanochannels were fabricated on Si (100) wafers by using photolithography and reactive ion etching (RIE) techniques. The channeled surfaces (Si channels) were then further modified by coating thin DLC film. Water contact angle of the modified and unmodified Si surfaces was examined by an anglemeter using the sessile-drop method. Nanotribological properties, namely friction and adhesion forces, of the Si channels coated with DLC (DLC-coated Si channels) were investigated in comparison with those of the flat Si, DLC-coated flat Si (flat DLC), and Si channels, using an atomic force microscope (AFM). Results showed that the DLC-coated Si channels greatly increased hydrophobicity of silicon surfaces. The DLC coating and Si channels themselves individually reduced adhesion and friction forces of the flat Si. Further, the DLC-coated Si channels exhibited the lowest values of these forces, owing to the combined effect of reduced contact area through the channeling and low surface energy of the DLC. This combined modification could prove a promising method for tribological applications at small scales.

• Journal of the Korean Ceramic Society
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• v.28 no.12
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• pp.961-968
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• 1991

The nature and composition of the surfaces of silicon nitride and β-Sialon powders were investigated using high voltage and high resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). β-Sialon powder was produced from Hadong kaolin by the carbothermic reduction and simultaneous nitridation. XPS showed that Al was contained in the surface of β-Sialon powder besides Si, N and O components, which is different from that of silicon nitride. It was supposed that Al in the surface of β-Sialon was bonded with oxygen from the oxygen-nitrogen ratio and the measurement of Al 2p binding energies. After both silicon nitride and β-Sialon powders were oxidized at 800℃ for 24h in air, nitrogen didn't exist in the surfaces and the depth of the oxide layer increased. The measurement of Si 2p binding energies showed that the chemical shifts occurred from Si3N2O and/or Si2N2O to SiO2 phase.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.547-553
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• 2004

A hemispherical asperity moving over a flat plane is simulated based on classical molecular dynamics. The asperity and the plane consist of silicon atoms whose interactions are governed by the Tersoff three-body potential. The gap between the asperity and the plane is maintained to produce attractive normal force in order to investigate the adhesive friction and wear. The simulation focuses on the influence of crystallographic orientation of the contacting surfaces and the moving direction. It is demonstrated that the adhesive friction and wear are lower when crystallographic orientations of the contacting surfaces are different, and also depend on the moving direction relative to the crystal1ographic orientation.

• Journal of Integrative Natural Science
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• v.4 no.4
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• pp.282-288
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• 2011

We describe the synthesis and characterization of silicon nanoparticles prepared by the solution reduction of silicon tetrachloride by lithium naphthalenide and subsequently with n-butyllithium at room temperature. These reactions produce silicon nanoparticles with surfaces that are covalently terminated with butyl group. Reaction with lithium aluminium hydride instead of n-butyllithium produces hydride-terminated silicon nanoparticles. The butyl or hydride terminated silicon nanoparticles can be suspended in hexane and their optical behavior have been characterized by photoluminescence spectroscopy. Stabilization of silicon nanoparticles were investigated upon illumination, indicating that as-prepared silicon nanoparticles are very stable at room temperature for several days.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.3025-3032
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• 2012

Carbon microcapsules containing silicon nanoparticles (Si NPs)-carbon nanotubes (CNTs) nanocomposite (Si-CNT@C) have been fabricated by a two step polymerization method. Silicon nanoparticles-carbon nanotubes (Si-CNT) nanohybrids were prepared with a wet-type beadsmill method. A polymer, which is easily removable by a thermal treatment (intermediate polymer) was polymerized on the outer surfaces of Si-CNT nanocomposites. Subsequently, another polymer, which can be carbonized by thermal heating (carbon precursor polymer) was incorporated onto the surfaces of pre-existing polymer layer. In this way, polymer precursor spheres containing Si-CNT nanohybrids were produced using a two step polymerization. The intermediate polymer must disappear during carbonization resulting in the formation of an internal free space. The carbon precursor polymer should transform to carbon shell to encapsulate remaining Si-CNT nanocomposites. Therefore, hollow carbon microcapsules containing Si-CNT nanocomposites could be obtained (Si-CNT@C). The successful fabrication was confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These final materials were employed for anode performance improvement in lithium ion battery. The cyclic performances of these Si-CNT@C microcapsules were measured with a lithium battery half cell tests.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1218-1223
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• 2004

Porous silicon materials have been shown to have bright prospects for applications in light emitting, solar cell, as well as light- and chemical-sensing devices. In this report, structures of porous silicon prepared by anodic etching in HF-based solution with various etching times were studied in detail by Atomic Force Microscopy and Small Angle X -ray Scattering technique using the high energy beam line at Pohang Light Source in Korea. The results showed the coexistence of the various pores with nanometer and submicrometer scales. For nanameter size pores, the mixed ones with two different shapes were identified: the larger ones in cylindrical shape and the smaller ones in spherical shape. Volume fractions of the cylindrical and the spherical pores were about equal and remained unchanged at all etching times investigated. On the whole uniform values of the specific surface area and of the size parameters of the pores were observed except for the larger specific surface area for the sample with the short etching time. The results implies that etching process causes the inner surfaces to become smoother while new pores are being generated. In all SAXS data at large Q vectors, Porod slope of -4 was observed, which supports the fact that the pores have smooth surfaces.

• Journal of the Korean Society of Visualization
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• v.16 no.2
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• pp.16-22
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• 2018

This study investigates dynamic wetting behaviors of a water droplet placed on surfaces with different wettability and nano-structures. Hydrophobic and hydrophilic properties on as-received silicon wafers were prepared by fabricating thin films of hydrophobic polymer and hydrophilic nanoparticles via layer-by-layer coating. Dynamic advancing contact angle of droplets on the prepared surfaces was measured at various moving velocities of triple contact line with a high-speed video camera. As advancing velocity of triple contact line increased, dynamic advancing contact angle on the as-received silicon and hydrophobic surfaces sharply increased up to $80^{\circ}$ in the range of order of mm/sec whereas the SiO2 nanoparticle-coated hydrophilic surface maintained low contact angles of about $30^{\circ}$ and then it gradually increased in the velocity range of order of hundred mm/sec. The improved dynamic wetting ability observed on the nanostructured hydrophilic surface can benefit the performance of various phase-change heat transfer phenomena under forced convective flow.

• Journal of Integrative Natural Science
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• v.2 no.1
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• pp.28-31
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• 2009

We describe the synthesis and characterization of silicon nanoparticles prepared by the soluton reduction of SiCl4. These reactions produce Si nanoparticles with surfaces that are covalently terminated. The resultant organic derivatized Si nanoparticles as well as a probable distribution of Water-soluble Si nanoparticles are observed and characterized by photoluminescence(PL) spectroscopy. This work focuses originally on the organic- and water-soluble silicon nanoparticles in terms of the photoluminescence. Further this work displays probably the first layout of hydrogen terminated Si nanoparticles synthesized in solution at room temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.497-502
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• 1998

To understand the effect of surface roughness on silicon wafer bonding, a continuum mechanical model is presented. This model is based on Obreimoff's experiment and the contact theory of rough surfaces. The surface energy of silicon was calculated to be much reduced than the theoretical value. Problems are discussed concerning surface film effects and the assumption of constant asperity radius and statistical distribution function.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.239-243
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• 1999

At Present, 200mm wafer technology is being applied for commercial fabrications of 64, 128, and 256 M DRAM devices, and 300mm technology will be evolved for 1G DRAM devices in the early 21th century, recognizing limitations of several process technologies. In particular recognition has been realized in harmful effects of surface contamination of trace metals introduced during devicing processes. Such a guide line for surface metal contamination has been proposed as 1E9 and 1E10 atoms/$\textrm{cm}^2$ of individual metal contamination for wafering and devicing of 1G DRAM, respectively, and so its measurement limit should be at least 1E8 atoms/$\textrm{cm}^2$. The detection limit of present measurement systems is 2E9 atoms/$\textrm{cm}^2$ obtainable with TRXFA(Total Reflection X-Ray Fluorescence Analysis). TRXFA is nondestructive and the simplest in terms of operation, and it maps the whole wafer surfaces but needs detection improvement. X-Ray intensity produced with synchrotron accelerator is much higher than that of conventional X-ray sources by order of 4-5 magnitudes. Hence theoretically its reactivity with silicon surfaces is expected to be much higher than the conventional one, realizing improvement of detection limit. X-ray produced with synchrotron accelerator is illuminated at a very low angle with silicon wafer surfaces such as 0.1 degree and reflects totally. Hence informations only from surface can be collected and utilized without overlapping with bulk informations. This study shows the total reflection phenomenon and quantitative improvement of detection limit for metallic contamination. It is confirmed that synchrotron X-ray can be a very promising alternative for realizing improvement of detection limit for the next generation devices.