• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.176-186
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• 1998

Pure Pt, Co and their alloy thin films with three different compositions (Pt66-Co34, Pt40-Co60 and Pt18-Co82) were deposited on Si(100) wafers and proposed as a set of certified reference materials (CRM) for the quantification and standardization of surface compositional analysis. The compositions of the binary alloy thin films were controlled by in-situ XPS analyses and the certified compositions of the films have been determined by ICP-AES and RBS analyses after thin film growth. Through comparison of the compositions determined by in-situ XPS with those by ICP, relatively accurate compositions could be obtained with a matrix effect correction. Standard deviations of XPS and AES round robin tests with the Pt-Co alloy thin films were large up to about 4%. On the other hand, the average compositions of the Pt-Co alloy thin films by two methods were in a good agreement within 1%. The formation of a Pt rich surface layer by ion beam sputtering indicates that the surface modification by preferential sputtering must be understood for a better compositional analysis.

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.374-380
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• 2011

Carbon coils could be synthesized on nickel catalyst layer-deposited silicon oxide substrate using $C_2H_2$ and $H_2$ as source gases and $SF_6$ as an additive gas under thermal chemical vapor deposition system. The characteristics (formation density and morphology) of as-grown carbon coils according to the injection stage of $SF_6$ gas incorporation were investigated. A continuous injecting of $SF_6$ gas flow could give rise to many types of carbon coils-related geometries, namely linear tub, micro-sized coil, nano-sized coil, and wave-like nano-sized coil. However, the limitation of the geometry as the nano-sized geometries of carbon coils could be achieved by the incorporation of $SF_6$ in a short time (1 min) during the initial deposition stage. A delayed injection of a short time $SF_6$ gas flow can deteriorate the limitation of the geometries. It confirms that the injection time and its starting point of $SF_6$ gas flow would be very important to determine the geometries of carbon coils.

• Journal of the Korean Society for Heat Treatment
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• v.27 no.1
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• pp.23-26
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• 2014

Ga doped ZnO (GZO) single layer and GZO/ZnO bi-layered films were deposited on glass substrates by radio frequency magnetron sputtering and then the influence of film thickness on the structural, electrical, and optical properties of the films was considered. Thicknesses of the GZO/ZnO films was varied as GZO 100 nm, GZO 85 nm/ZnO 15 nm and GZO 70 nm/ZnO 30 nm, respectively. The observed result means that optical transmittance and electrical resistivity of the films were influenced with film thickness and GZO 85 nm/ZnO 15 nm bilayered films show the higher figure of merit than that of the films prepared other films in this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5758-5762
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• 2014

Electrostatically-actuated Micro device have been used widely in a variety of integrated sensors and actuators. Electrostatically-actuated micro devices with a gap of several micrometers or less between the electrodes have shown failure problems by electrostatic adhesion. To improve this adhesion phenomenon, micro devices of varying lengths and widths in electrodes were fabricated, and an alumina coating was then deposited using atomic layer deposition technology. The effects of improving adhesion phenomenon were compared by measuring the pull-in voltage before and after the coating process. The pull-in voltage increased with increasing length of the upper electrode after the coating. An increase in the electrode area results in an increase in the pull-in voltage after coating. The alumina coating method applied to improve the adhesion on an electrostatically-actuated micro device was observed as an effective method.

• Journal of Powder Materials
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• v.18 no.6
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• pp.532-537
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• 2011

Thermally stable $TiO_2$/Pt/$SiO_2$ core-shell nanocatalyst has been synthesized by chemical processes. Citrated capped Pt nanoparticles were deposited on amine functionalized silica produced by Stober process. Ultrathin layer of titania was coated on Pt/$SiO_2$ for preventing sintering of the metal nanoparticles at high temperatures. Thermal stability of the metal-oxide hybrid catalyst was demonstrated heating the sample up to $600^{\circ}C$ in air and by investigating the morphology and integrity of the structure by transmission electron spectroscopy. The surface analysis of the constituent elements was performed by X-ray photoemission spectroscopy. The catalytic activity of the hybrid catalysts was investigated by CO oxidation reaction with oxygen as a model reaction.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.213-218
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• 1999

Fructans are polyfructose molecules that function as nonstructural storage carbohydrates in several plants. In addition, it has been suggested that, due to their solubility, they can play an important role in helping plants survive periods of osmotic stress. In order to study the effect of levan synthesis on plant growth, the coding region of the levansucrase gene, which was isolated from Zymomonas mobilis, was introduced into tobacco plants using Agrobacterium tumefaciens-mediated transformation. The presence of the levansucrase gene in transgenic plants was verified by genomic DNA gel blot analysis. RNA gel blot and immunoblot analyses showed an accumulation of the corresponding transcript and protein product of the bacterial levansucrase gene in transgenic plants. Furthermore, a thin layer chromatography analysis revealed that fructans were synthesized and deposited in transgenic tobacco plants. When $T_1$ seeds were germinated and grown under polyethylene glycol-mediated drought stress or cold stress, the transgenic seedlings displayed a substantially higher level of growth than that of untransformed plants. These results suggest that fructans may playa significant role in the tolerance of plants under osmotic stress.

• Journal of Microbiology and Biotechnology
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• v.22 no.11
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• pp.1568-1574
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• 2012

Microbiological calcium carbonate precipitation (MCCP) has been investigated for its ability to improve the durability of cement mortar. However, very few strains have been applied to crack remediation and strengthening of cementitious materials. In this study, we report the biodeposition of Bacillus subtilis 168 and its ability to enhance the durability of cement material. B. subtilis 168 was applied to the surface of cement specimens. The results showed a new layer of deposited organic-inorganic composites on the surface of the cement paste. In addition, the water permeability of the cement paste treated with B. subtilis 168 was lower than that of non-treated specimens. Furthermore, artificial cracks in the cement paste were completely remediated by the biodeposition of B. subtilis 168. The compressive strength of cement mortar treated with B. subtilis 168 increased by about 19.5% when compared with samples completed with only B4 medium. Taken together, these findings suggest that the biodeposition of B. subtilis 168 could be used as a sealing and coating agent to improve the strength and water resistance of concrete. This is the first paper to report the application of Bacillus subtilis 168 for its ability to improve the durability of cement mortar through calcium carbonate precipitation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.832-835
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• 2001

We report the structural and electrical properties of hafnium oxide (HfO$_2$) films with tungsten silicide (WSi$_2$) metal gate. In this study, HfO$_2$thin films were fabricated by oxidation of sputtered Hf metal films on Si, and WSi$_2$was deposited directly on HfO$_2$by LPCVD. The hysteresis windows in C-V curves of the WSi$_2$HfO$_2$/Si MOS capacitors were negligible (<20 mV), and had no dependence on frequency from 10 kHz to 1 MHz and bias ramp rate from 10 mV to 1 V. In addition, leakage current was very low in the range of 10$^{-9}$ ~10$^{-10}$ A to ~ 1 V, which was due to the formation of interfacial hafnium silicate layer between HfO$_2$and Si. After PMA (post metallization annealing) of the WSi$_2$/HfO$_2$/Si MOS capacitors at 500 $^{\circ}C$ EOT (equivalent oxide thickness) was reduced from 26 to 22 $\AA$ and the leakage current was reduced by approximately one order as compared to that measured before annealing. These results indicate that the effect of fluorine diffusion is negligible and annealing minimizes the etching damage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.976-979
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• 2002

A focusing grating coupler (FGC) was not fabricated by the 'Continuous Path Control' writing strategy but by an electron-beam lithography system of more general exposure mode, which matches not only the address grid with the grating period but also an integer multiple of the address grid resolution (5 nm), To more simplify the fabrication, we are able to reduce a process step without large decrease of pattern quality by excluding a conducting material or layer such as metal (Al, Cr, Au), which are deposited on top or bottom of an e-beam resist to prevent charge build-up during e-beam exposure. A grating pitch period and an aperture feature size of the FGC designed and fabricated by e-beam lithography and reactive ion etching were ranged over 384.3 nm to 448.2 nm, and $0.5{\times}0.5mm^2$ area, respectively, This fabrication method presented will reduce processing time and improve the grating quality by means of a consideration of the address grid resolpution, grating direction, pitch size and shapes when exposing. Here our investigations concentrate on the design and efficient fabrication results of the FGC for coupling from slab waveguide to a spot in free space.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.172-173
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• 2006

Metal-ferroelectric-insulator-semiconductor (MFIS) structures with $Bi_{3.35}La_{0.75}Ti_3O_{12}$ (BLT) ferroelectric film and Zirconium oxide ($ZrO_2$) layer were fabricated on p-type Si(100). $ZrO_2$ and BLT films were prepared by sol-gel technique. Surface morphologies of $ZrO_2$ and BLT film were measured by atomic force microscope (AFM). The electrical characteristics of Au/$ZrO_2$/Si and Au/BLT/$ZrO_2$/Si film were investigated by C-V and I-V measurements. No hysteretic characteristics was observed in the C-V curve of the Au/$ZrO_2$/Si structure. The memory window width m C-V curve of the Au/BLT/$ZrO_2$/Si diode was about 1.3 V for a voltage sweep of ${\pm}5$ V. The leakage current of Au/$ZrO_2$/Si and Au/BLT/$ZrO_2$/Si structures were about $3{\times}10^{-8}$ A at 30 MV/cm and $3{\times}10^{-8}$ A at 3 MV/cm, respectively.