• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.550-558
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• 1989

Polycrystalline diamond films have been deposited on Si wafer Ly hot W filament CVD method using CH4H2 mixtures. The effects of surface pretreatment, W filament temperature, CH4 volume fraction, and addition of water vapor on the growth rate and morphology of the films were investigated. Surface pretretment was essential for depositing a continuous diamond film. Raising the filament temperature resulted in an increased growth rate and a better crystal quality of the film. As the methane content is varied from 0.5% to 5%, well-faceted crystals gradually transformed into spherical particles of non-diamond phase with a simultaneous increase in the growth rate. Addition of water vapor markedly improved the crystallinity to produce crystalline particles even with 5% methane mixture.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.128-133
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• 2007

In this study, we observed the shapes of CNTs formed with the thinckness of catalyst. Catalyst layer was grown by magnetron sputtering method and the thickness of Ni catalyst is the range from 20 to 80 nm. Also, the synthesis of CNT with Ni catalyst thickness was grown by hot-filament PECVD method. And, we investigated the composition of CNTs by using EDS measurement, also observed the shapes of CNTs by using HRTEM and FESEM measurements. In the result, through the TEM analysis, we observed the empty inside of CNTs and the multiwall CNTs, also confirmed the tip of CNT containing Ni. The composition of CNTs are consisted of an element of C, Ti, and Ni. As you shown the growth shapes of CNTs, the pretreatment of the catalyst before te growth of CNTs changed the particle size of the catalysts and grown the CNTs of the different shapes. Consequently, the best vertically alined and well-arranged CNTs exhibited from the substrate deposited at the catalyst thickness of 40 nm.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.54-54
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• 2018

To optimize the deposition parameters of diamond films, the temperature, pressure, and distance between the filament and the susceptor need to be considered. However, it is difficult to precisely measure and predict the filament and susceptor temperature in relation to the applied power in the hot filament chemical vapor deposition (HFCVD) system. In this study the temperature distribution inside the system was numerically calculated for the applied powers of 12, 14, 16 and 18 kW. The applied power needed to achieve the appropriate temperature at a constant pressure and other conditions was deduced, and applied to actual experimental depositions. The numerical simulation was conducted using the commercial computational fluent dynamics software, ANSYS-FLUENT. To account for radiative heat-transfer in the HFCVD reactor, the discrete ordinate (DO) model was used. The temperatures of the filament surface and the susceptor at different power levels were predicted to be 2512 ~ 2802 K, and 1076 ~ 1198 K, respectively. Based on the numerical calculations, experiments were performed. The simulated temperatures for the filament surface were in good agreement with experimental temperatures measured using a 2-color pyrometer. The results showed that the highest deposition rate and the lowest deposition of non-diamond was obtained at a power of 16 kW.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.120-120
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• 2006

탄소나노튜브는 nm급의 크기에 높은 전기전도도, 열전도 효율, 감한 기계적 강도 등의 장점을 가지며, FED(Field Emission Display), 극미세 전자 스위칭 소자, SET(Single Electron Transistor), AFM(Atomic Force Microscope) tip등 여러 분야로의 응용을 연구하고 있다. 본 연구에서는 탄소나노튜브를 Si 웨이퍼 위에 Ni/Ti 금속층을 촉매층으로 사용하고, 암모니아($NH_3$)가스와 아세틸렌 ($C_2H_2$)가스를 각각 희석가스와 성장원으로 사용하여 합성하였다. 탄소나노튜브의 성장은 Hot filament 화학기상증측(HFPECVD) 방식을 사용하였으며, 이 방법은 다량의 합성, 높은 균일성, 좋은 정렬 특성등의 장점을 가진다. 성장 온도는 탄소나노튜브의 성장 특성을 변화시키는 중요한 요소이다. 성장 온도에 따라 수직적 성장, 성장 밀도등의 특성 변화를 관찰하였다. 성장된 탄소나노튜브층 성분 분석은 에너지 분산형 X-선 측정기(EDS)를 통해 관찰하였고, 끝단에 촉매층이 존재하는 30~50 nm 폭을 가진 다중벽 탄소나노튜브를 고배율 투과전자현미경(HRTEM) 분석을 통해 관찰하였다. 전계방사 주사전자현미경(FESEM) 분석을 동해 1~3${\mu}m$의 길이를 가진 탄소나노튜브가 높은 밀도로 성장된 것을 확인하였다.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.129-137
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• 2004

This paper presents an accelerated life test for burnout of tungsten filament of incandescent lamp. From failure analyses of field samples, it is shown that their root causes are local heating or hot sports in the filament caused by tungsten evaporation and wire sag. Finite element analysis is performed to evaluate the effect of vibration and impact for burnout, but any points of stress concentration or structural weakness are not found in the sample. To estimate the burnout life of lamp, an accelerated life test is planned by using quality function deployment and fractional factorial design, where voltage, vibration, and temperature are selected as accelerating variables. We assumed that Weibull lifetime distribution and a generalized linear model of life-stress relationship hold through goodness of fit test and test for common shape parameter of the distribution. Using accelerated life testing software, we estimated the common shape parameter of Weibull distribution, life-stress relationship, and accelerating factor.

• The Korean Journal of Ceramics
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• v.4 no.1
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• pp.25-27
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• 1998

The effect of gas activation on the formation of SiC layer on Si substrate using methane as a carbon source was investigated. Tungsten filaments, heated above 200$0^{\circ}C$, were used to activate the methane-hydrogen mixed gas. The dissociation of methane gas by the heated filament was enough to form a SiC layer successfully, which was very difficult without any activation. The SiC layer formed on the Si substrate was crystalline and nearly epitaxial as measured by X-ray diffraction. The SiC layer formed on the Si substrate was crystalline and nearly epitaxial as measured by X-ray diffraction. The stoichiometry was also close to 1:1. However, the characteristic of the SiC layer was dependent on the heat-treatment condition. The general behavior of the layer growth with the variables was discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.5
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• pp.563-572
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• 1998

An experimental study of hot filament chemical vapor deposition(HFCVD) has been carried out for the fabrication of diamond thin film. Of particular interest is the measurement of deposition uniformity on large substrates. Experimental apparatus including a vacuum chamber, heating elements, etc. has been designed and manufactured. Deposition profiles for different pretreatment powders and different flow rates have been measured in conjunction with the measurement of substrate temperature distribution on a large substrate surface. As the flow rate increases, deposition rate increases, however, the crystallinity becomes worse. Higher growth rate has been found on the region closer to the center location where substrate temperature is higher. The crystallinity has been improved as gas flow rate decreases. The growth rate and morphology of deposition were identified by SEM and the existence of diamond phase was proved by Raman spectroscopy.

• Journal of the Korean Ceramic Society
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• v.56 no.3
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• pp.269-276
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• 2019

This article reports on the conditions required for the growth of crystalline boron films on silicon substrates by hot filament chemical vapor deposition method. The reactive gas was 3% diborane diluted in hydrogen. The films were characterized by optical, electronic, and atomic force microscopies; x-ray diffraction; and energy dispersive, electron energy loss, Raman, x-ray photoelectron, and Auger spectroscopies. The parameters that affect the morphologies of the films have been investigated. It was concluded that faceted crystals are produced at low B₂H₆ flows and working pressures below 200 mT. α-boron is produced between 530 and 600℃. Deposition outside this range produces thin films with a wide variety of morphologies. This result indicates that the films crystallize through a process called "abnormal or discontinuous grain growth." It is assumed that this is due to the anisotropic surfaces of boron allotropes.

• Journal of Korean Vacuum Science & Technology
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• v.4 no.3
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• pp.86-90
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• 2000

ZnO : Al films were prepared through the optimization process of aluminum content and substrate temperature in rf-magnetron sputtering. When hydrogenation was performed on these films using a hot filament method, all films showed improvement in conductivity although more conductive film showed less improvement. When the substrate temperature ($T_H$) was varied from $25^{\circ}C\;to\;300^{\circ}C$ during hydrogenation, the resistivity was reduced more at higher $T_H$ (more than 30% at $T_H=300^{\circ}C$) Thus, two methods were developed to suppress the dehydrogenation in ZnO : Al films : (1) capping with amorphous silicon thin film as a diffusion barrier, and (2) cooling during hydrogenation.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.05a
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• pp.146-146
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• 2002