• Korean Journal of Metals and Materials
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• v.48 no.7
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• pp.660-666
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• 2010

30 nm thick Ni layers were deposited on a glass substrate by e-beam evaporation. Subsequently, 30 nm or 60 nm ${\alpha}-Si:H$ layers were grown at low temperatures ($<220^{\circ}C$) on the 30 nm Ni/Glass substrate by catalytic CVD (chemical vapor deposition). The sheet resistance, phase, microstructure, depth profile and surface roughness of the $\alpha-Si:H$ layers were examined using a four-point probe, HRXRD (high resolution Xray diffraction), Raman Spectroscopy, FE-SEM (field emission-scanning electron microscopy), TEM (transmission electron microscope) and AES depth profiler. The Ni layers reacted with Si to form NiSi layers with a low sheet resistance of $10{\Omega}/{\Box}$. The crystallinty of the $\alpha-Si:H$ layers on NiSi was up to 60% according to Raman spectroscopy. These results show that both nano-scale NiSi layers and crystalline Si layers can be formed simultaneously on a Ni deposited glass substrate using the proposed low temperature catalytic CVD process.

• Journal of Industrial Technology
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• v.39 no.1
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• pp.33-39
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• 2019

This paper addresses effects of nanoscale structures on structural colors of micropatterned transparent substrate by light diffraction. Structural colors is widely investigated because they present colors without any chemical pigments. Typically structural colors is presented by diffraction of light on a micropatterned surface or by multiple interference of light on a surface containing a periodic or quasi-periodic nano-structures. In this paper, each structural colors induced by quasi-periodic nano-structures, periodic micro-structures, and nano/micro dual structures is measured in order to investigate effects of nanoscale and microscale structures on structural colors in the transparent substrate. Using pre-fabricated pattern mold and hot-embossing process, nanoscale and microscale structures are replicated on the transparent PMMA(Poly methyl methacrylate) substrate. Nanoscale and microscale pattern molds are prepared by anodic oxidation process of aluminum sheet and by reactive ion etching process of silicon wafer, respectively. Structural colors are captured by digital camera, and their optical transmittance spectrum are measured by UV/visible spectrometer. From experimental results, we found that nano-structures provide monotonic colors by multiple interference, and micro-structures induce iridescent colors by diffraction of light. Structural colors is permanent and unchangeable, thus it can be used in various application field such as security, color filter and so on.

• Journal of Industrial Technology
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• v.39 no.1
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• pp.7-14
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• 2019

Carbon nanotubes (CNT) on metal substrates are definitely beneficial because they can maintain robust mechanical stability and high conductivity between CNT and metal interfaces. Here, we report direct growth of CNT on Ni-based superalloy, Inconel 600, using thermal chemical vapor deposition (CVD) with acetylene feedstock in the growth temperature range of $400-725^{\circ}C$. Furthermore, we studied the effect of substrate pretreatment on the growth yield enhancement and growth temperature decrease of CNT on Inconel 600. Activation energy (AE) for CNT growth was estimated from the CNT height change with respect to the growth temperature. The AE values significantly decreased from 205.03 to 24.35 kJ/mol by the pretreatment of thermal oxidation of Inconel substrate at $725^{\circ}C$ under ambient. Higher oxidation temperature tends to have lower activation energy. The results have shown the importance of pretreatment temperature on CNT growth yield and growth temperature decrease.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1561-1567
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• 2021

In this study, we have studied synthesis of zirconia-alumina composite coating materials via a low-temperature sol-gel process. The zirconia-alumina composites were prepared by coating zirconia precursor, alumina precursor, and organosilane mixture on a polyethylene terephthalate substrate through three steps: sol-gel process, low-temperature photocuring process, and heat treatment process. The structural properties and element analysis of the composites were confirmed by FT-IR and XPS. The coated composite showed a transmittance of 96% or more in the visible light region with a wavelength of 420 nm or more and pencil hardness of 9H or more. In case of the composite of the molar ratio of zirconia and alumina of 1:4, the highest nanoindentation hardness was measured with 1.212 GPa.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.1-7
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• 2017

Multi-wafer planetary type chemical vapor deposition reactors are widely used in thin film growth and suitable for large scale production because of the high degree of growth rate uniformity and process reproducibility. In this study, a two-dimensional model for estimating the effect of the gap between satellite and wafer on the wafer surface temperature distribution is developed and analyzed using computational fluid dynamics technique. The simulation results are compared with the results obtained from an analytical method. The simulation results show that a drop in the temperature is noticed in the center of the wafer, the temperature difference between the center and wafer edges is about $5{\sim}7^{\circ}C$ for all different ranges of the gap, and the temperature of the wafer surface decreases when the size of the gap increases. The simulation results show a good agreement with the analytical ones which is based on one-dimensional heat conduction model.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.61-66
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• 2022

This study is to increase the surface area and maximize the effect of the catalyst by coating a nanometersized metal catalyst material on the anode layer using atomic layer deposition (ALD) technology. ALD process is known to produce uniform films with well-controlled thickness at the atomic level on substrates. We measured the performance by coating metals (Ni) on Ni/YSZ, which is the most widely known anode material for solid oxide fuel cells. ALD coatings began to show a decrease in cell performance over 3 nm coatings.

• Progress in Superconductivity and Cryogenics
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• v.12 no.3
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• pp.7-11
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• 2010

For many large-scale applications of high-temperature superconducting materials, large critical current density($J_c$) in high applied magnetic fields are required. A number of methods have been reported to introduce artificial pinning centers(APCs) in $YBa_2Cu_3O_{7-\delta}$(YBCO) films for enhancement of their $J_c$. In this work, we investigated electric characteristic of YBCO films on $SrTiO_3$ (100) substrates whose surfaces were modified by the introduction of Au nanoparticles (AuNPs). Au nanoparticles were uniformly dispersed on STO substrates with one of typical solution techniques, self assembled monolayer. After heating the STO substrates with Au nanoparticles, the size of Au nanoparticles was around 29~32 nm in height and 41~49 nm in diameter. XRD diffraction patterns taken on the YBCO film with Au nanoparticles show the c-axis orientation. The measured $T_c$ of YBCO /AuNPs films was around 89K and the $J_c$ was 0.75 MA/$cm^2$ at 65 K and 1 T.

• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.127-133
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• 2022

Two types of charged particle-type electronic paper display panels with electrodes using ITO and CNT are fabricated to compare durability and electro-optical characteristics. The sheet resistance of the ITO electrode is 10 (ohm/sq.), and the sheet resistance of the CNT electrode is 300, 600, 1000 (ohm/sq.), and durability is carried out by impact and flexibility measurements. Variation in case of the ITO electrode begins at shocks of 40 times and curvature radius of 10 mm, and no change is observed in the CNT electrode. The driving voltage, electric field required for particle movement, reflectivity, and response time measurements show similar results for all ITO and CNT electrodes.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.149-154
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• 2007

Nanoimprint lithography (NIL) is useful technique because of its low cost and high throughput capability for the fabrication of sub-micrometer patterns which has potential applications in micro-optics, magnetic memory devices, bio sensors, and photonic crystals. Usually, a chemical surface treatment of the stamp is needed to ensure a clean release after imprinting and to protect the expensive original master against contamination. Meanwhile, adhesion promoter between resin and substrate is also important in the nanoscale pattern. In this work, we have investigated the effect of surface treatment using silane coupling agent as release layer and adhesion promoter for UV-Nanoimprint lithography. Uniform SAM (self-assembled monolayer) could be fabricated by vapor deposition method. Vapor phase process eliminates the use of organic solvents and greatly simplifies the handling of the sample. It was also proven that 3-acryloxypropyl methyl dichlorosilane (APMDS) could strongly improve the adhesion force between resin and substrate compared with common planarization layer such as DUV-30J or oxygen plasma treatment.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.593-598
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• 2016

We report on the preparation of reduced graphene oxide (rGO)/single-walled carbon nanotubes (SWNTs) electrodes deposited onto flexible polyethylene terephthalate (PET) via spray coating technique. The highest capacitance value of the unbent rGO/SWNTs electrode was $82Fg^{-1}$ in 1 M $H_2SO_4$ at $100mVs^{-1}$, which decreased to $38Fg^{-1}$ after 500 bending cycle. Further characterization, including galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy (EIS), showed that the rGO/SWNTs electrode retained a well-defined capacitive response after repetitive bending cycle. Overall, the rGO/SWNTs composite electrode showed reasonable electrochemical properties even prolonged bending cycle. Approximately 50% of the initial capacitance for the rGO/SWNTs composite electrode is remained after 500 bending cycle, making the electrode a potential option for flexible energy storage applications.