• Journal of the Korean Ceramic Society
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• v.40 no.6
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• pp.589-593
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• 2003

Silica based Planar Lightwave Circuits (PLC) have been applied to various kinds of wave-guided optical passive devices. SiO$_2$ (buffer) and GeO$_2$-SiO$_2$ (core) thick films have been deposited by Flame Hydrolysis Deposition (FHD). The SiO$_2$ films were produced by the flame hydrolysis reaction of halide materials such as SiCl$_4$, POCl$_3$ and BCl$_3$ into an oxy-hydrogen torch. The P concentration increased from 2.0 to 2.8 at％ on increasing the POCl$_3$/BCl$_3$ flow ratio. The refractive index increased from 1.4584 to 1.4605 on increasing the POC1$_3$/BC1$_3$ flow ratio from 0.6 to 2.6. The refractive index of GeO$_2$-SiO$_2$ films was controlled by the GeCl$_4$ flow rate. The refractive index increased from 1.4615 to 1.4809 on increasing the GeCl$_4$ flow rate from 30 to 120 sccm.

• Journal of the Korean Ceramic Society
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• v.44 no.10
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• pp.589-595
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• 2007

Physical properties of sputtered YSZ thin film electrolytes on anode thin film by spray pyrolisis has been investigated to realize the porous electrode and dense electrolyte multilayer structure for micro solid oxide fuel cells. It is shown that for better crystallinity and density, YSZ need to be deposited at an elevated temperature. However, if pure NiO anode was used for high temperature deposition, massive defects such as spalling and delamination were induced due to high thermal expansion mismatch. By changing anode to NiOCGO composite, defects were significantly reduced even at high deposition temperature. Further research on realization of full cells by processing hybridization and cell performance characterization will be performed in near future.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.183-189
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• 2004

Cuprous oxide (Cu$_2$O) thin films are cathodically deposited on Indium Tin Oxide (ITO) substrate. The as-deposited films were heat-treated at 30$0^{\circ}C$ to obtain Cu$_2$O. After the heat treatment, the film was changed from Cu metal into Cu$_2$O phase. The phase, morphology and photocurrent density of the films were dependent on the preparation conditions of deposition time, applied voltage, and the duration of heat treatment. The Cu$_2$O films were characterized by X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). The apparent grain size of the films formed by the normal method was larger than those grown by the pulse method. The CU$_2$O film what was deposited at -0.7 V for 300 sec and then, calcined at 30$0^{\circ}C$ for 1 h showed the predominant photocurrent density of 1048 $\mu$A/$\textrm{cm}^2$. And the stability of Cu$_2$O electrodes were improved with chemically deposited TiO$_2$ thin films on Cu$_2$O.

• Journal of the Korean Ceramic Society
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• v.40 no.12
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• pp.1165-1169
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• 2003

The Ta$_2$O$_{5}$ thin film was deposited on Si-(III) and glass substrate with the change of Ar:O$_2$ gas flow rate in the assist ion gun by the Dual ion-Beam Sputtering (DIBS). As the $O_2$ gas flow of the assist ion gun was decreased, the deposition rate of the thin films decreased. The refractive index was fixed (2.11, at 1550 nm) without regarding to $O_2$ gas flow of the range 3∼12 sccm in assist ion gun. The condition of Ar:O$_2$=3:12 was formatted stoichiometry composition of Ta$_2$O$_{5}$ and the ms roughness was small (0.183 nm).

• Journal of the Korean Ceramic Society
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• v.43 no.6 s.289
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• pp.362-368
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• 2006

Epitaxial $Ba_{0.5}Sr_{0.5}TiO_3$ (BSTO) thin films have been grown on TiN buffered Si (001) substrates by Pulsed Laser Deposition (PLD) method and the effects of substrate temperature and oxygen partial pressure during the deposition on their dielectric properties and crystallinity were investigated. The crystal orientation, epitaxy nature, and microstructure of oxide thin films were investigated using X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Thin films were prepared with laser fluence of $4.2\;J/cm^2\;and\;3\;J/cm^2$, repetition rate of 8 Hz and 10 Hz, substrate temperatures of $700^{\circ}C$ and ranging from $350^{\circ}C\;to\;700^{\circ}C$ for TiN and oxide respectively. BSTO thin-films were grown on TiN-buffered Si substrates at various oxygen partial pressure ranging from $1{\times}10^{-4}$ torr to $1{\times}10^{-5}$ torr. The TiN buffer layer and BSTO thin films were grown with cube-on-cube epitaxial orientation relationship of $[110](001)_{BSTO}{\parallel}[110](001)_{TiN}{\parallel}[110](001)_{Si}$. The crystallinity of BSTO thin films was improved with increasing substrate temperature. C-axis lattice parameters of BSTO thin films, calculated from XRD ${\theta}-2{\theta}$ scans, decreased from 0.408 m to 0.404 nm and the dielectric constants of BSTO epitaxial thin films increased from 440 to 938 with increasing processing oxygen partial pressure.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.487-492
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• 2011

The effect of the application of lanthanum strontrium manganite and yttria-stabilized zirconia (LSM-YSZ) nano-composite fabricated by pulsed laser deposition (PLD) as a cathode of solid oxide fuel cell (SOFC) is studied. A gradient-structure thin-film cathode composed of 1 micron-thick LSM-YSZ deposited at an ambient pressure ($P_{amb}$) of 200 mTorr; 2 micron-thick LSM-YSZ deposited at a $P_{amb}$ of 300 mTorr; and 2 micron-thick lanthanum strontium cobaltite (LSC) current collecting layer was fabricated on an anode-supported SOFC with an ~8 micron-thick YSZ electrolyte. In comparison with a 1 micron-thick nano-structure single-phase LSM cathode fabricated by PLD, it was obviously effective to increase triple phase boundaries (TPB) over the whole thickness of the cathode layer by employing the composite and increasing the physical thickness of the cathode. Both polarization and ohmic resistances of the cell were significantly reduced and the power output of the cell was improved by a factor of 1.6.

• Analytical Science and Technology
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• v.6 no.2
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• pp.239-246
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• 1993

The structure of $(BaSr)TiO_3$ thin film deposited on ITO coated glass, bare glass and (100) Si substrates was not changed, but the crystallinity was improved by the polycrystalline ITO layer and (100) Si substrate. The composition of $(BaSr)TiO_3$ thin film deposited on ITO coated glass was nearly stoichiometric ((Ba+Sr)/Ti=1.08~1.09) and very uniform through all deposition process. But as the deposition temperature increases, the interdiffusion between grown thin film and ITO layer and between ITO layer and base glass is severer. $(BaSr)TiO_3$ thin film deposited on ITO coated glass substrate was highly transparent. The refractive index($n_f$) of $(BaSr)TiO_3$ thin film deposited on ITO coated glass was 2.138~2.286 as a function of substrate temperature.

• Journal of the Korean Ceramic Society
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• v.34 no.6
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• pp.636-644
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• 1997

The effect of various processing parameters, in particular the substrate and filament temperature, on the nucleation of diamond has been studied for the hot filament CVD process with a negative bias on the substrate. As far as the substrate temperature was maintained around the critical temperature of 73$0^{\circ}C$, the nucleation of diamond increased with increasing filament temperature. The maximum nucleation density of ~ 2$\times$109/$\textrm{cm}^2$ was obtained under the condition of filament temperature of 230$0^{\circ}C$, substrate temperature of 75$0^{\circ}C$, bias voltage of 300V, methane concentration of 20%, and deposition time of 2 hours. This nucleation density is about the same as those obtained in previous investigations. For fixed substrate temperatures, the nucleation density varies up to about 103 times depending on experimental conditions. This result is different from that of Reinke, et al. When the substrate temperature was above 80$0^{\circ}C$, a silkworm~shaped carbon phase was co-deposited with hemispherical microcrystalline diamond, and its amount increased with increasing substrate temperature. The Raman spectrum of the silkworm-shaped carbon was the same as that of graphitic soot. The silkworm-shaped carbon was etched and disappeared under the same as that of graphitic soot. The silkworm-shaped carbon was etched and disappeared under the deposition condition of diamond, implying that it did not affect the nucleation of diamond.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.552-552
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• 2013

In our study we consider Al2O3 ceramic substrates for Plasma Surface Treatments in order to improve deposited diamond surface and increase diamond deposition rate by applying DBD (Dielectric Barrier Dischrge) system. Because Plasma Surface Treatments was used as a modification method of material surface properties like surface free energy, wettability, and adhesion. By applying Plasma Surface Treatments diamond films are deposited on the Al2O3 ceramic substrates. DC Arc Plasmatron with mathane and hydrogen gases is used. Deposited diamond films are investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) is studied. As a result, nanocrystalline diamond films were identified by using SEM and diamond properties in XRD peaks at (111, $43.8{\Box}$, (220, $75.3{\Box}$ and (311, $90.4{\Box}$ were shown. Absorption peaks in FTIR spectrum, caused by CHx sp3 bond stretching of CVD diamond films, were identified as well. Finally, we improved such parameters as depostion rate ($2.3{\mu}m$/h), diamond surface uniformity, and impurities level by applying Plasma Surface Treatments. These experimental results show the importance of Plasma Surface Treatments for diamond deposition by a plasma source.

• Korean Journal of Metals and Materials
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• v.50 no.8
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• pp.569-573
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• 2012

In order to understand the difference in SiC deposition between the $CH_3SiCl_3-H_2$ and $C_3H_8-SiCl_4-H_2$ systems, we calculate the phase stability among ${\beta}$-SiC, graphite and silicon. We constructed the phase-diagram of ${\beta}$-SiC over graphite and silicon via computational thermodynamic calculation considering pressure (P), temperature (T) and gas composition (C) as variables. Both P-T-C diagrams showed a very steep phase boundary between the SiC+C and SiC region perpendicular to the H/Si axis, and also showed an SiC+Si region with a H/Si value of up to 6700 in the $C_3H_8-SiCl_4-H_2$, and 5000 in the $CH_3SiCl_3-H_2$ system. This difference in phase boundaries is explained by the ratio of Cl to Si, which is 4 for the $C_3H_8-SiCl_4-H_2$ system and 3 for the $C_3H_8-SiCl_4-H_2$ system. Because the C/Si ratio is fixed at 1 in the $CH_3SiCl_3-H_2$ system while it can be variable in the $C_3H_8-SiCl_4-H_2$ system, the functionally graded material is applicable for better mechanical bonding during SiC coating on graphite substrate in the $C_3H_8-SiCl_4-H_2$ system.