• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1144-1149
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• 2001

In this research, the fabrication of Si/SiO$_2$optical waveguide amplifier by FHD(Flame Hydrolysis Deposition) and Solution Doping was carried out. It was observed that the reduction of fluorescence was prevented up to 0.14 wt% Er whn 0.48 wt% Al was doped and the FWHA of $1.5mutextrm{m}$ fluorescence band increased by 5 nm as increasing amount of Al. Therefore from these results, we could confirm depressing concentration quenching of Er ions and increasing FWHM of fluorescence spectrum by addition of Al.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.55-60
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• 1999

${\beta}$-SiC thin film was deposited on a Si substrate without buffer layer using a single precursor of Hexamethyldisilane (Si2(CH3)6) by chemical vapor deposition method. HCI gas was introduced into hexamethyldisilane /H2 gas mixture, and the feeding schedule of HCI and precursor gases was modified in order to enhance the selectivity of SiC deposition between a Si substrate and a SiO2 mask. The effect of HCI gas on the surface roughness of the SiC film was investigated and typical electrical properties of the SiC film were also investigated by Hall measurement.

• Journal of the Korean Ceramic Society
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• v.36 no.5
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• pp.504-512
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• 1999

The high-quality carbon nanofibers were prepared by chemical vapor deposition of gas mixtures of CO-H2 and C3H8-H2 over Fe-Cu and Ni-Cu bimetallic catalysts. The yield and structure of carbon nanofiber produced were altered by the change of catalyst composition and reaction temperature. The high yields were obtained around 500$^{\circ}C$ with e-Cu catalyst and around 700-750$^{\circ}C$ with Ni-Cu catalyst and the relatively higher yields were obtained with the bimetallic catalyst containing 50-90% of Ni and Fe respectively in comparison with the pure metals. The carbon nanofibers produced over the Fe-Cu catalyst at around 500$^{\circ}C$ with the maximum yields had the highest surface ares of 160-200 m2/g around 650$^{\circ}C$ which was slightly lower than the temperature for maximum yields. In order to examine the characteristics of carbon nanofibers as catalyst support Ni and Co metals were supporte on the carbon nanofibers and CO hydrogenation reaction was performed with the catalysts. The particle size distribution of Ni and Co supported over the carbon nanofibers were 6-15 nm and the CO hydrogenation reaction rate with the carbon-nanofiber supported catalysts was much higher than that over the other supports.

• Journal of the Korean Ceramic Society
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• v.35 no.1
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• pp.88-96
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• 1998

The structural and electrical properties of titanium dioxide(TiO2) thin films deposited on p-type (100) si and 4$^{\circ}$off(100) Si substartes by metalorganic chemical vapor deposition (MOCVD) have been studied with post rapid thermal annealing. TiO2 thin films of anatase phase were grown at 300-500$^{\circ}C$ using titanium post rapid thermal annealing at a temperature of 800$^{\circ}C$ for 30sec. rutile phase was observed in the condition of the deposition temperature over 350$^{\circ}C$ in the ambient air atmosphere and at 500$^{\circ}C$ in cacuu,. SEM and AFM study show-ed surface roughness were increased slightly from 40${\AA}$to 55${\AA}$ after annealing due to grain growth and phase transformation. From capacitane-voltage measurement of Al/TiO2./p-Si structure after annealing we obtained ideal capacitance-voltage characteristics of MOS structure with dielectric constant of 16-22 in case of (100) Si and about 30- in case of 4$^{\circ}$off(100) Si but showed the higher leakage current.

• Journal of the Korean Ceramic Society
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• v.52 no.3
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• pp.209-214
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• 2015

Silicon nitride films were deposited at $100^{\circ}C$ by using the catalytic chemical vapor deposition technique. The source gas mixing ratio, $R_N=[NH_3]/[SiH_4]$, was varied from 10 to 30, and the hydrogen dilution ratio, $R_H=[H_2]/[SiH_4]$, was varied from 20 to 100. The breakdown field strength reached a maximum value at $R_N=20$ and $R_H=20$, whereas the resistivity decreased in the same sample. The relative permittivity had a positive correlation with the breakdown field strength. The capacitance-voltage threshold curve showed an asymmetric hysteresis loop, which became more squared as $R_H$ increased. The width of the hysteresis window showed a negative correlation with the slope of the transition region, implying that the combined effect of $R_N$ and $R_H$ overides the interface defects while creating charge storage sites in the bulk region.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.446-450
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• 2013

TRISO coated particles with a ZrC barrier layer were fabricated by a fluidized-bed chemical vapor deposition (FBCVD) method for a use in a very high temperature gas-cooled reactor (VHTR). The ZrC layer was deposited by the reaction between $ZrCl_4$ and $CH_4$ gases at $1500^{\circ}C$ in an $Ar+H_2$ mixture gas. The amount of free carbon codeposited with in ZrC was changed by controlling the dilution gas ratio. Near-stoichiometric ZrC phase was also deposited when an impeller was employed to a $ZrCl_4$ vaporizer which effectively inhibited the agglomeration of $ZrCl_4$ powders during the deposition process. A near-stoichiometric ZrC coating layer had smooth surface while ZrC containing the free carbon had rough surface with tumulose structure. Surface roughness of ZrC increased further as the amount of free carbon increased.

• Journal of the Korean Ceramic Society
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• v.54 no.5
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• pp.443-447
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• 2017

The initial reaction of hexachlorodisilane ($Si_2Cl_6$, HCDS) on amorphous silica ($SiO_2$) surface for atomic layer deposition was investigated using density functional theory. Two representative reaction sites on the amorphous $SiO_2$ surface for HCDS reaction, a surface hydroxyl and a two-membered ring, were considered. The reaction energy barrier for HCDS on both sites was higher than its adsorption energy, indicating that it would desorb from the surface rather than react with the surface. At high temperature range, some HCDSs can have kinetic energy high enough to overcome the reaction energy barrier. The HCDS reaction on top of the reacted HCDS was investigated to confirm its self-limiting characteristics.

• Journal of the Korean Ceramic Society
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• v.37 no.8
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• pp.731-738
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• 2000

KLN(K3Li2Nb5O15) has attracted a great deal of attention for their potential usefulness in piezoelectric, electro-optic, nonlinear optic, and pyroelectirc devices. Especially, the KLN single crystal has been studied in the field of optics and electronics. However it is hard to produce good quality single crystals due to the crack propagation during crystal growing. One of the solutions of this problem is prepartion of thin film. But the intensive study has not been conducted so far. In this study, after the KLN thin film were prepared by R.F. magnetron Sputtering method on SiO2/Si substrate, the post-annealing methods of RTA(rapid thermal annealin) and IPA(insitu post annealing) were employed. The deposition condition of KLN thin film was RF power(100 W), Working pressure(100 mtorr). The commonness of both RAT and IPA was that the higher were deposition and post annealing temperature, the higher was the intensity of XRD but the less surface roughness. The difference of post-annealing methods affected XRD phase and surface condition very much. And in IPA process, the influence of O2 had much effect on the formation of KLN phase.

• Journal of the Korean Ceramic Society
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• v.43 no.11 s.294
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• pp.734-737
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• 2006

A series of manganite-based superlattices composed of half-metallic $La_{2/3}Sr_{1/3}MnO_3/LaMnO_3$ and insulating LaMnO$_3$ stacking layers were fabricated by employing pulsed laser deposition method. The dc resistivity increased drastically by simply reducing the stacking periodicity. The resistivity enhancement was accompanied by a gradual decrease in the temperature (T$_c$) of the Metal-to-Insulator Transition (MIT). This observation was interpreted as a small decrease in the effective metallic fraction near the percolation threshold. For the stacking periodicity less than a certain critical value, there appeared another transition to an insulating state at temperatures far below T$_c$. This low-temperature transition seems to be closely related to the AF-type (C-type) orbital ordering in newly formed insulating domains.

• Journal of the Korean Ceramic Society
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• v.45 no.1
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• pp.30-35
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• 2008

In this paper, CdS/Cd(Cu)S thin films and diodes were manufactured via a chemical bath deposition (CBD) process, and the effects of $NH_4Cl$ and TEA(triethylamine) on the properties of the films were examined. The addition of $NH_4Cl$ significantly increased the thickness of the CdS and Cd(Cu)S films, however, the addition of TEA decreased the thickness in both cases slightly. The addition of $NH_4Cl$ along with TEA increased the film thickness more effectively compared to the addition of only $NH_4Cl$. The thickness of the CdS film prepared from an aqueous solution of 0.007 M $CdSO_4$, 1.3 M $NH_4OH$, 0.03 M $SC(NH_2)_2$, 0.0001 M TEA and 0.03 M $NH_4Cl$ was 310 nm. Dark resistivity of the CdS film was $1.2{\times}10^3\;{\Omega}cm$ and the photo resistivity with $500\;W/cm^2$ irradiation of white light was $20{\Omega}cm$. The Cd(Cu)S/CdS thin film diodes prepared by CBD showed good rectifying characteristics.