• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.474-475
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• 2018

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1661-1664
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• 2010

The photocatalytic decomposition of toluene vapor by bare and $TiO_2$-coated carbon fibers was studied. Atomic layer deposition (ALD) was used to perform the $TiO_2$ coating. We show that, under our conditions, the photocatalytic activity of bare carbon fibers was comparable with that of $TiO_2$ films, which are known to be good photocatalysts. The origin of the high photocatalytic activity of bare carbon fibers is discussed.

• Korean Journal of Materials Research
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• v.30 no.12
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• pp.660-665
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• 2020

Silicon heterojunction solar cells can achieve high conversion efficiency with a simple structure. In this study, we investigate the passivation characteristics of VOx thin films as a hole-selective contact layer using ALD (atomic layer deposition). Passivation characteristics improve with iVoc (implied open-circuit voltage) of 662 mV and minority carrier lifetime of 73.9 µs after post-deposition annealing (PDA) at 100 ℃. The improved values are mainly attributed to a decrease in carbon during the VOx thin film process after PDA. However, once it is annealed at temperatures above 250 ℃ the properties are rapidly degraded. X-ray photoelectron spectroscopy is used to analyze the chemical states of the VOx thin film. As the annealing temperature increases, it shows more formation of SiOx at the interface increases. The ratio of V5+ to V4+, which is the oxidation states of vanadium oxide thin films, are 6:4 for both as-deposition and annealing at 100 ℃, and 5:5 for annealing at 300 ℃. The lower the carbon content of the ALD VOx film and the higher the V5+ ratio, the better the passivation characteristics.

• Transactions on Electrical and Electronic Materials
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• v.4 no.4
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• pp.1-6
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• 2003

Aluminum oxide ($Al_2O_3$) nanotubes and nanorods were fabricated by coating and filling of multiwalled carbon nanotubes (MWNTs) with atomic-layer deposition (ALD). $Al_2O_3$ material was deposited on the MWNTs at a substrate temperature of $300^{\circ}C$ using trimethylaluminum and distilled water. Transmission electron microscopy, high resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and selected area electron diffraction of the deposited MWNTs revealed that amorphous $Al_2O_3$ material coats the MWNTs conformally and that this material fills the inside of the MWNTs. These illustrate that ALD has an excellent capability to coat and fill any three-dimensional shapes of MWNTs conformally without producing any crystallites.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.282-284
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• 2011

Based on graphene oxide and multi-walled carbon nanotube layers, a wireless bi-layer actuator that can be remotely controlled with an electromagnetic induction system has been developed. The graphene-based bi-layer actuator exhibits a large one-way bending deformation under eddy current stimuli due to asymmetrical responses originating from the temperature difference of the two different carbon layers. In order to validate one-way bending actuation, the coefficients of thermal expansion of carbon nanotube and graphene oxide are mathematically formulated in this study based on the atomic bonding energy related to the bonding length. The newly designed graphene-based bi-layer actuator is highly sensitive to electromagnetic wave irradiation thus it can trigger a new actuation mode for the realization of remotely controllable actuators and is expected to have potential applications in various wireless systems.

• Journal of Powder Materials
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• v.25 no.1
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• pp.43-47
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• 2018

Carbon nanofibers (CNF) are widely used as active agents for electrodes in Li-ion secondary battery cells, supercapacitors, and fuel cells. Nanoscale coatings on CNF electrodes can increase the output and lifespan of battery devices. Atomic layer deposition (ALD) can control the coating thickness at the nanoscale regardless of the shape, suitable for coating CNFs. However, because the CNF surface comprises stable C-C bonds, initiating homogeneous nuclear formation is difficult because of the lack of initial nucleation sites. This study introduces uniform nucleation site formation on CNF surfaces to promote a uniform $SnO_2$ layer. We pretreat the CNF surface by introducing $H_2O$ or $Al_2O_3$ (trimethylaluminum + $H_2O$) before the $SnO_2$ ALD process to form active sites on the CNF surface. Transmission electron microscopy and energy-dispersive spectroscopy both identify the $SnO_2$ layer morphology on the CNF. The $Al_2O_3$-pretreated sample shows a uniform $SnO_2$ layer, while island-type $SnO_x$ layers grow sparsely on the $H_2O$-pretreated or untreated CNF.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1001-1002
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• 2013

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.1
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• pp.7-11
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• 2020

Carbon solubility on the paste deposition methods in the carbon-doped TiZrN coating was investigated in terms of lattice distortion and atomic concentration. After depositing the carbon paste by the dip coating, spin coating and screen printing, the laser was ablated to form the carbon gradient layer. Thickness and the concentration of doped carbon depended on the paste deposition method. Crystal structure analysis indicated that more lattice distortion occurred when coating layers were doped with spin coating and screen printing than when coating layers were doped with dip coating. The XPS depth profile showed that the thickness of carbon gradient layer by dip coating was about 30 nm, spin coating and screen printing are approximately 100 nm, formed more gradient layer. The hardness before laser carburization was about 30 GPa, and the hardness of 31 GPa with dip coating and 37 GPa with spin coating and screen printing. It was indicated that paste deposition methods for laser carburization contributed to lattice distortion and gradient layer.

• Korean Journal of Materials Research
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• v.17 no.3
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• pp.160-166
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• 2007

TRISO coatings on $ZrO_{2}$ surrogate kernels were conducted by a fluidized-bed chemical vapor deposition (FBCVD) method. Effects of the deposition temperature and the gas flow rate on the properties of SiC layer were investigated in the TRISO-coated particles. Deposition rate of the SiC layer decreased as the deposition temperature increased in the temperature range of $1460^{\circ}-1550^{\circ}C$. At the deposition temperature of $1550^{\circ}C$ the SiC layer contained an excess carbon, whereas the SiC layers had stoichiometric compositions at $1460^{\circ}C\;and\;1500^{\circ}C$. Hardness and elastic modulus measured by a nanoindentation method were the highest in the SiC layer deposited at $1500^{\circ}C$. The SiC layer deposited at the gas flow rate of 4000 sccm exhibited a high porosity and contained large pores more than $1{\mu}m$, being due to a violent spouting of particles. On the other hand, the SiC layer deposited at 2500 sccm revealed the lowest porosity.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.345-345
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• 2010

Thin film of $TiO_2$ deposited on carbon paper was fabricated by atomic layer deposition (ALD) using titanium isopropoxide (TTIP) and $H_2O$ as precursors. In this work, the photocatalytic activities of $TiO_2$ films with and without e-beam treatment were compared. The samples were treated by e-beam using e-beam energy of 1MeV and exposure range between 5 and 15kGy. The photocatalytic activity was evaluated by the photocatalytic degradation of methyleneblue (MB) under UV irradiation (365nm) at room temperature using an UV-vis spectroscopy. The surface properties were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The sample treated by the low radiation dose has more catalytic activity than other ones. SEM images show that the high radiation dose caused the $TiO_2$ to aggregation on carbon paper. Due to the aggregation of $TiO_2$, the partially exposed carbon paper was oxidized.