• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.33-38
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• 1998

TiYN coated high speed steel tools have been developed and their tool lifes were assessed. First yttrium alloyed titanium target was manufactured, then using the arc ion plating(AIP) technique TiYN coating was deposited onto high speed steel substrate. Three kinds of varying thickness of TiYN coated tools were prepared. Cutting tests were carried out with theses tools and for comparison with the commercially available uncoated, TiN, TiCN and TiAlN coated tools. During the cutting tests flank wear width vs. cutting time was measured. It has been revealed that the newly developed TiYN coated tools show superior tool life characteristics to others.

• Proceedings of the KIEE Conference
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• 1999.11a
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• pp.31-34
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• 1999

In the present study, we fabricated stoichiometric $(Ba_{1-x}Sr_x)TiO_3$ thin films at various substrate temperature and contents using of magnetron sputtering method on optimized Pt-based electrodes (Pt/TiN/$SiO_2$/Si). The substate temperature deposited at 200[ $^{\circ}C$], 400[$^{\circ}C$] and 600[$^{\circ}C$] and crystalline BST thin films show above 400[$^{\circ}C$]. Also, the composition of $(Ba_{1-x}Sr_x)TiO_3$ thin films deposited on Si wafer substrate at 400[$^{\circ}C$] were closed to stoichiometry($1.015{\sim}1.093$ in A/B ratio), but compositional deviation from a stoichiometry is larger as $SrCO_3$ is added. The drastic decrease of dielectric constant and increase of dielectric loss in $(Ba_{1-x}Sr_x)TiO_3$thin films is observed above 100[kHz]. V-I characteristics of $(Ba_{1-x}Sr_x)TiO_3$ thin films show the decrease of leakage current with the increase of $SrCO_3$ contents.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.77-82
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• 1995

PTCR(Positive Temperature Coefficient of Resistivity) thermistor in thin film BaTiO$_{3}$ system was prepared by using radio frequency(13.56 MHz) and DC magnetron sputter equipment. Polycrystalline, surface structure, and R-T(Resistivity-Temperature) characteristics of the specimens were measured by X-ray diffraction(D-Max3, Rigaku, Japan), SEM(Scanning Electron Microscopy: M.JSM84 01, Japan), and insulation resistance measuring system (Keithley 719), respectively. Thin films characteristics of the thermistor showed different properties depending on the substrate even with the same sputtering condition. The thin film formed on the A1$_{2}$O$_{3}$ substrate showed a good crystalline and a low resistivity at below curie point. However, the thin films prepared on slide glass and Si wafer were amorphous. The thicknesses of the three samples prepared under the same process conditions were 700[.angs.], 637.75[.angs.], and 715[.angs.], respectively.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.183-190
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• 1997

The wear behaviors of $Al_2O_3-40%TiO_2$ deposited on casting aluminum alloy(ASTM A356) by plasma spray against SiC ball have been investigated experimentally. Friction and wear tests are carried out at room temperature. The friction coefficient of $Al_2O_3-40%TiO_2$ coating is lower than that of pure $Al_2O_3$ coating(APS). It is found that low friction correspond to low wear and high friction to high wear in the experimental result. The thickness of $Al_2O_3-40%TiO_2$ coatings indicated the existence of the optimal coating thickness. It is found that a voids and porosities of coating surface result in the crack generated. As the tensile stresses in coating increased with the increased friction coefficient. The columnar grain of coating will be fractured to achieve the critical stress. It is found that the cohesive of splats and the porosity of surface play a role in wear characteristics. It is suggested that the mismatch of thermal expansion of substrate and coating play an important role in wear performance. Tensile and compressire under thermo-mechanical stress may be occurred by the mismatch between thermal expansion of substrate and coating. This crack propagation above interface is observed in SEM.

• Tribology and Lubricants
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• v.15 no.1
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• pp.39-45
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• 1999

The wear behavior of $Al_2$O$_3$-40%TiO$_2$deposited on casted aluminum alloy (ASTM A356) by APS (Air Plasma Spray) against SiC ball has been investigated in this work. Wear tests were carried out at room temperature. The friction coefficient of $Al_2$O$_3$-40%TiO$_2$coating is lower than that of pure $Al_2$O$_3$coating(APS). $Al_2$O$_3$-40%TiO$_2$coating indicated the existence of the optimal coating thickness. It is found that voids and pores of coating surface resulted in the generation of cracks, and the cohesive of splats and the porosity of surface play a role in wear characteristics. It is suggested that the mismatch of thermal expansion of substrate and coating play an important role in wear performance. Tension and compression under thermo-mechanical stress may be occurred by the mismatch between thermal expansion of substrate and coating. The crack propagation above interface is observed in SEM.

• Korean Journal of Materials Research
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• v.11 no.9
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• pp.776-780
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• 2001

$SiO_2$ and polycrystalline Si layers were sequentially grown on (100) Si. NiSi was formed on this substrate from a 20nm Ni layer or a 20nm Ni/5nm Ti bilayer by rapid thermal annealing (RTA) at $300~500^{\circ}C$ to compare thermal stability. In addition, MOS capacitors were fabricated by depositing a 20nm Ni layer on the Poly-Si/$SiO_2$substrate, RTA at $400^{\circ}C$ to form NiSi, $BF_2$ or As implantation and finally drive- in annealing at $500~800^{\circ}C$ to evaluate electrical characteristics. When annealed at $400^{\circ}C$, NiSi made from both a Ni monolayer and a Ni/Ti bilayer showed excellent thermal stability. But NiSi made from a Ni/Ti bilayer was thermally unstable at $500^{\circ}C$. This was attributed to the formation of insignificantly small amount of NiSi due to suppressed Ni diffusion through the Ti layer. PMOS and NMOS capacitors made by using a Ni monolayer and the SADS(silicide as a dopant source) method showed good C-V characteristics, when drive-in annealed at $500^{\circ}C$ for 20sec., and$ 600^{\circ}C$ for 80sec. respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.3
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• pp.62-67
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• 2009

Pt thin films on Cr or Ti interlayer were deposited onto a tungsten carbide(WC) substrate by the ion beam assisted DC magnetron sputtering. The various atomic percent of Cr and Ti underneath of the Pt films were prepared to examine the total thin film characteristics. The microstructure and surface analysis of the specimen were conducted by using the SEM, XRD and AFM. Mechanical properties such as hardness and adhesion strength of Pt thin film also were examined. The interlayer of pure Ti was formed with 40 nm thickness while that of pure Cr was done with 50 nm as standard reference. The growth rate of either Cr or Ti thin film was almost same under the same deposition conditions. The SEM images showed that anisotropic grain of Pt thin films consisting of dense columnar structures irrespectively grew from the different target compositions. The values of hardness and adhesion strength of Cr/Pt thin film coated on a WC substrate were higher than those of Ti/Pt thin film.

• Korean Journal of Crystallography
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• v.11 no.3
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• pp.167-172
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• 2000

CaTiO₃:Pr phosphor thin films were prepared on Si(100), ZnO/glass, Corning glass and ITO/glass by rf magnetron reactive sputtering. The effects of deposition parameters such as oxygen partial pressure, substrate temperature, and annealing conditions on crystallinity and compositional variation of the films were investigated. PL spectra of CaTiO₃:Pr phosphor thin films exhibited red regime peaking at 613 nm and enhanced PL intensity was observed for the film annealed in vacuum atmosphere as compared to the deposit annealed in N₂ environment.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.453.1-453.1
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• 2014

Fluorine-doped tin oxide (FTO), which is commonly used in dye-sensitized solar cells (DSSCs), is a promising material of transparent conducting oxides (TCOs) because of advantages such as high chemical stability, high resistance, high optical transparency (>80% at 550nm), and low electrical resistivity (${\sim}10-4{\Omega}{\cdot}cm$). Especially, dye-sensitized solar cells (DSSCs) have been actively studied since Gratzel's research group required FTO substrate as a charge collector. When FTO substrates are used in DSSCs, photo-injected electrons may experience recombination at interface between dye-bonded semiconductor oxides ($TiO_2$) on FTO substrate and the electrolyte. To solve these problems, one is that because recombination at FTO substrate cannot be neglected, thin $TiO_2$ layer on FTO substrate as a blocking layer was introduced. The other is to control the morphology of surface on FTO substrate to reduce a loss of electrons. The structural, electrical, and optical characteristics of morphology controlled-FTO thin films as TCO materials were analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Hall Effect Measurement, and UV spectrophotometer. The performance of DSSCs fabricated with morphology controlled FTO substrates was performed using Power Conversion Efficiency (PCE). We will discuss these results in detail in Conference.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1440-1441
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• 2006

In this study, we synthesized CNTs(carbon nanotubes) on the glass substrate by microwave plasma enhanced chemical vapor deposition (MPECVD), Effect of bias voltage on the grown behavior and morphology of CNTs were investigated. Recently, it has been proposed that aligned CNTs can also be achieved by the application of electric bias to the substrate during growth, the first time reported the bias effect such that the nanotube alignment occurred only when a positive bias was applied to the substrate whereas no aligned growth occurred under a negative bias and no tube growth was observed without bias. On the country, several researchers reported some different observations that aligned nanotubes could also be grown under negative substrate biases. This discrepancy as for the effect of positive and negative bias may indicate that the bias effect is not fully understood yet. The glass and Si wafers were first deposited with TiN buffer layer by r.f sputtering method, and then Ni catalyst same method, The thickness of TiN and Ni layer were 200 nm and 60 nm, respectively. The main process parameters include the substrate bias (0 to - 300 V), and deposition pressure (8 to 20 torr).