• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.169-174
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• 2007

TRISO coated fuel particle is one of the most important materials for hydrogen production using HTGR (high temperature gas cooled reactors). It is composed of three isotropic layers: inner pyrolytic carbon (IPyC), silicon carbide (SiC), outer pyrolytic carbon (OPyC) layers. In this study, TRISO coated fuel particle layers were deposited through CVD process in a horizontal hot wall deposition system. Also the computational simulations of input gas velocity, temperature profile and pressure in the reaction chamber were conducted with varying process variable (i.e temperature and input gas ratios). As deposition temperature increased, microstructure, chemical composition and growth behavior changed and deposition rate increased. The simulation showed that the change of reactant states affected growth rate at each position of the susceptor. The experimental results showed a close correlation with the simulation results.

• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.346-354
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• 1993

The diamond particles and films were deposited on Si and qurtz substrate for $CH_4-H_2$ mixed gas by using RF plasma CVD. The temperature of substrate and the thinkness of films deposited on Si substrate were uniformly kept up by inserting metal plate between substrate and substrate holder. On increasing the reaction pressure in the same discharge power, the morphologies of films were changed from well-defind films to micro-crystal or ball-like. When diamond films were deposited on Si substrate from $CH_4-H_2$ mixed gas, we obtained well-defined diamond films at lower concentration than 0.5 vol% of $CH_4/H_2$. The deposited diamond films were indentified by SEM, XRD and Raman spectroscopy.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.9
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• pp.45-51
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• 2014

This work carried out for the effective synthesis characteristics of graphene nanowall film by controlling the electric field in a RF plasma CVD process. For that, the bipolar bias voltage was applied to the substrate such as Si and glass materials for the best chemical reaction of positive and negative charges existing in the plasma. For supplying the seed formation sites on substrate and removing the oxidation layer on the substrate surface, the electron bombardment into substrates was performed by a positive few voltage in hydrogen plasma. After that, hydrocarbon film, which is not a graphene nanowall, was deposited on substrates under a negative bias voltage with hydrogen and methane gases. At this step, the film on substrates could not easily identify due to its transparent characteristics. However, the transparent film was easily changed into graphene nanowall by the final hydrogen plasma treatment process. The resultant raman spectra shows the existence of significant large 2D peaks corresponding to the graphene.

• Journal of the Korean Vacuum Society
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• v.2 no.2
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• pp.255-260
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• 1993

UHV-LCVD system was constructed for high quality silicon nitride thin film fabrication. This system consisted of a reaction chamber, an introduction chamber with sample load lock entry, a carbinet for gas manipulation controlling gas flow, a $CO_2$ laser and a Fourier transform mass spectrometer. Although the UHV-LCVD system construction was more sophisticated than low pressure CVD, highly pure thin films were fabricated by controlling gas mixing ratio and flow rate in ultra high vacuum surroundings.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1243-1245
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• 1994

SiN films were deposited in $Si_2H_6$(99.9%), $NH_3$(99.99%) gas mixture with carrier gas $N_2$ on Si substrate by ArF Excimer Laser CVD. SiN film deposition conditions that are substrate temperature and Laser average power were varied in order to investigate the dependence of SiN film on the condition. A post-deposition anneal was performed to examine variation of fixed charge density in the films. The deposition rate was increased as the substrate temperature and Laser power were increased during film deposition. The refractive index was increased with increasing substrate temperature, but it didn't have the dependence on Laser power. The fixed charge density was decreased when a post-deposition anneal was performed.

• Journal of the Korean institute of surface engineering
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• v.28 no.3
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• pp.133-141
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• 1995

The deposition characteristics of diamond films were investigated for three different substrates : Si, Inconel 600 and steel. Diamond films were prepared by microwave plasma CVD method using $CH_4$, $H_2$ and $O_2$ as reaction gases. The deposited films were analyzed with SEM, Raman spectroscopy and ellipsometer. For Si substrate, diamond films were successfully obtained for most of the deposition conditions used in this study. As the $CH_4$ flow rate decreased and the $O_2$ flow rate increased, the quality of the film was improved due to the reduced non-diamond phase in the film. For Inconel 600 substrate, the surface pretreatment with diamond powders was required to deposit a continuous diamond film. The films deposited at temperatures of $600^{\circ}C$ and $700^{\circ}C$ had mainly diamond phase, but they were peeled off locally due to the difference in the thermal expansion coefficient between the substrate and the deposited films. The films deposited at $500^{\circ}C$ and $850^{\circ}C$ had only the graphitic carbon phase. For steel substrate, all of the films deposited had only the graphitie carbon phase. We speculated that the formation of diamond nuclei on the steel substrate was inhibited due to the diffusion of carbon atoms into the steel substrate which has a large amount of carbon solubility.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.173-183
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• 1998

An optimization procedure to find the inlet concentration profile that yields the most uniform deposition rate in a cylindrical CVD chamber has been developed. Assuming that the chemical reaction time is negligibly small, a SIMPLE based finite-volume method is adopted to solve the fully elliptic equations for momentum, temperature, and concentration. The inlet concentration profile is expressed by a linear combination of Chebyshev polynomials and the coefficients of which are determined by the local random search technique. It is shown that the present method is very effective in improving the uniformity of the deposition rate, especially when Re is high and/or the wafer is placed close to the inlet. The optimal profiles have been obtained for various Re, Gr, and geometry combinations.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.37-44
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• 1995

TiO2 fine powders were synthesized using oxygenolysis and hydrolysis reaction of TiCl4 vapor in gas phase. The TiO2 powder synthesized showed morphological differences depending on reaction system as follows: TiCl4-O2 reaction system produced the monosized particles having polyhedral shape with well-defined crystal planes and the particles did not agglomerate into secondary particles. TiCl4-H2O reaction system, whereas, produced the spherical secondary particles which consisted of fine primary particles. Other powder characteristics such as particle size, impurity content and rutile content are also reported in this study.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.294-297
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• 2000

Boron Phosphide films were deposited on the glass substrate at low temperature, 550$^{\circ}C$, by the reaction of B$_2$H$\sub$6/ with PH$_3$ using CVD. N$_2$ was employed as carrier gas. The deposition rate was 1000${\AA}$/min and the refractive index of film was 2.6. The data of XRD show that the film has the preferred orientation of (1 0 1). The VIS spectrophotometer's data proved that the films are transparent in the visible range. Also, we performed AFM, FT-IR measurement. To investigate the annealing effect, the samples were annealed for 1hour, 3hours at 550$^{\circ}C$ and tested.

• Journal of the Korean Vacuum Society
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• v.4 no.S1
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• pp.118-128
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• 1995

Copper(l) hexafluoroacetonate trimethylvinylsilane [Cu(hafac)(TMVS)]를 precursor로 사용하여 증착온도 $160~330^{\circ}C$ 범위에서 TiN 모재 위에 낮은 전기비저항값(~2 $\mu$$\Omega$.cm)을 갖는 CVD Cu 박막을 제조하였고, 증착온도에 따른 Cu 박막의 특성을 조사하여 증착온도가 Cu 박막의 미세구조와 전기비저항에 미치는 영향을 고찰하였다. Cu 증착의 활성화에너지는 표면반응제한지역(surface-reaction-limited region)에서 10.8 kcal/mol 이었다. 표면반응에 의해 증착속도가 결정되는 증착온도 $200^{\circ}C$ 이하에서 증착된 Cu 박막은 낮은 비저항값을 갖는 치밀한 박막이었고 step coverage 또한 우수하였다. 이에 반해 물질전달이 증착속도를 결정하는 증착온도 $200^{\circ}C$이상에서 증착된 Cu 박막은 연결상태가 불량한 구형의 결정립들로 이루어져 있어서 높은 비저항값과 거친 표면형상을 나타내었다. 이와 함께 증착온도에 따른 Cu 박막의 결정립 크기, 배향성 등도 조사하였다.