• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.69-73
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• 1997

Microwave Plasma assisted CVD (Chemical Vapor Deposition) and DC Plasma CVD were used to prepare thin and thick diamond film, respectively. Diamond coated silicon nitride and fiee standing diamond thick film were eroded by silicon carbide particles. The velocity of the solid particle was about 220m/sec. Phase transformation and the other crack formation were investigated by using Raman spectroscopy and microscopy.

• Journal of the Korean Ceramic Society
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• v.40 no.12
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• pp.1150-1153
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• 2003

Carbon nanofilaments were formed on silicon substrate using microwave plasma-enhanced chemical vapor deposition method. The structures of carbon nanofilaments were identified as carbon nanotubes or carbon nanofibers. The formation of bamboo-like carbon nanotubes was initiated by the application of the bias voltage during the plasma reaction. The growth kinetics of bamboo-like carbon nanotubes increased with increasing the bias voltage. The growth direction of bamboo-like carbon nanotubes was vertical to the substrate.

• Journal of the Korean Applied Science and Technology
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• v.21 no.4
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• pp.289-299
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• 2004

Multi-walled carbon nanotubes (CNTs) were prepared by microwave plasma chemical vapor deposition (MPCVD) using various combination of binary catalysts and methane precursor. The maximum yield (10.3 %) of CNTs was obtained using a methane-hydrogen-nitrogen mixture with volume ratio of 1:1:2 at 1000 W of microwave power. As the microwave power increased up to 1000 W, the deposition yield of CNTs raised from 4.1 % to 10. 3 %. However, the prepared CNTs at 800 W showed the more crystalline structure than those prepared at 1000 W. The prepared CNTs over different binary catalysts had various structural conformations such as aligned cylinder, bamboo, and nanofibers. The Id/Ig value of CNTs over$Fe-Fe/Al_2O_3, $Co-Co/Al_2O_3, and $Co-Cu/Al_2O_3 were in the range of 0.89${\sim}$0.93. Among the various binary catalysts used, $Fe-Co./Al_2O_3 showed the highest yield.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.905-908
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• 2000

The growth properties of diamond grain were examined by Raman spectroscopy and microscope images. Diamond thin films were prepared on single crystal Si wafers by microwave Plasma chemical vapor deposition. Preparation conditions, substrate temperature, boron concentration and deposition time were controlled differently. Prepared diamond thin films have different surface morphology and grain size respectively Diamond grain size was gradually changed by substrate temperature. The biggest diamond grain size was observed in the substrate, which has highest temperature. The diamond grain size by boron concentration was slightly changed but morphology of diamond grain became amorphous according to increasing of boron concentration. Time was also needed to be a big diamond grain. However, time was not a main factor for being a big diamond grain. Raman spectra of diamond film, which was deposited at high substrate temperature, showed sharp peaks at 1334$cm^{-1}$ / and these were characteristics of crystalline diamond. A broad peak centered at 1550$cm^{-1}$ /, corresponding to non-diamond component (sp$^2$carbon), could be observed in the substrate, which has low temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.80-80
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• 2010

Graphene has attracted tremendous attention for the last a few years due to it fascinating electrical, mechanical, and chemical properties. Up to now, several methods have been developed exclusively to prepare graphene, which include micromechanical cleavage, polycrystalline Ni employing chemical vapor deposition technique, solvent thermal reaction, thermal desorption of Si from SiC substrates, chemical routes via graphite intercalation compounds or graphite oxide. In particular, polycrystalline Ni foil and conventional chemical vapor deposition system have been widely used for synthesis of large-area graphene. [1-3] In this study, synthesis of mono-layer graphene on a Ni foil, the mixing ratio of hydrocarbon ($CH_4$) gas to hydrogen gas, microwave power, and growth time were systemically optimized. It is possible to synthesize a graphene at relatively lower temperature ($500^{\circ}C$) than those (${\sim}1000^{\circ}C$) of previous results. Also, we could control the number of graphene according to the growth conditions. The structural features such as surface morphology, crystallinity and number of layer were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM), transmission electron microscopy (TEM) and resonant Raman spectroscopy with 514 nm excitation wavelength. We believe that our approach for the synthesis of mono-layer graphene may be potentially useful for the development of many electronic devices.

• Journal of the Korean institute of surface engineering
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• v.44 no.4
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• pp.131-136
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• 2011

A kinetic study has been made for the growth of nanocrystalline diamond (NCD) particles to a continuous thin film on silicon substrate in a microwave plasma chemical vapor deposition reactor. Parameters of deposition have been microwave power of 1.2 kW, the chamber pressure of 110 Torr, and the Ar/$CH_4$ ratio of 200/2 sccm. The deposition has been carried out at temperatures in the range of $400\sim700^{\circ}C$ for the times of 0.5~16 h. It has been revealed that a continuous diamond film evolves from the growth and coalescence of diamond crystallites (or particles), which have been heterogeneously nucleated at the previously scratched sites. The diamond particles grow following an $h^2$ = k't relationship, where h is the height of particles, k' is the particle growth rate constant, and t is the deposition time. The k' values at the different deposition temperatures satisfy an Arrhenius equation with the apparent activation energy of 4.37 kcal/mol or 0.19 eV/ atom. The rate limiting step should be the diffusion of carbon species over the Si substrate surface. The growth of diamond film thickness (H) shows an H = kt relationship with deposition time, t. The film growth rate constant, k, values at the different deposition temperatures show another Arrhenius-type expression with the apparent activation energy of 3.89 kcal/mol or 0.17 eV/atom. In this case, the rate limiting step might be the incorporation reaction of carbon species from the plasma on the film surface.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.131.2-131.2
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• 2015

마이크로웨이브를 이용한 플라즈마는 효율적인 전자가열이 가능하며, 낮은 이온에너지를 가지는 고밀도 플라즈마를 생성시킬 수 있다는 장점이 있다. 최근 산화물 반도체 및 대화면 디스플레이 장치내 소자의 보호막 증착용으로 저온 PECVD (Plasma Enhanced Chemical Vapor Deposition) 공정 및 장치의 필요성에 따라 마이크로웨이브를 이용한 PECVD 장치가 주목 받고 있다. 본 연구에서는 실리콘 나이트라이드 공정 장치 개발을 위한 2차원 시뮬레이션 모델을 완성하였다. Global modeling을 이용하여 확보한 Chemical reaction data에 대한 검증을 하였다. Maxwell's equation, continuity equation, electromagnetic wave equation 등을 이용하여 Microwave의 파워 및 압력에 따른 전자 밀도, 전자 온도등의 플라즈마 변수의 변화를 관찰하였다. 또한 Navier Stokes equation을 추가하여 챔버 내의 Gas flow의 흐름을 고려한 시뮬레이션을 진행하여 분석하였다.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.4
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• pp.65-70
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• 2006

Carbon nanotubes (CNT) grown by chemical vapor deposition (CVD) and plasma enhanced chemical vapor deposition (PECVD), and followed by annealing at $400{\sim}500^{\circ}C$ were investigated for gas sensing under 1.5ppm $NO_{2}$ concentration at an operating temperature of $200^{\circ}C$. The electrical resistance of CNT sensor decreased with temperature, indicating a semiconductor type. The resistance of CNT sensor decreased with $NO_{2}$ adsorption. It was found that the sensitivity of sensor was affected by humidity and decreased under microwave irradiation for 3 minutes. The CNT sensor grown by PECVD had a higher sensitivity than that of CVD.

• Journal of the Korean Applied Science and Technology
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• v.21 no.2
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• pp.174-181
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• 2004

Multi-walled carbon nanotubes (CNTs) were prepared by thermal chemical vapor deposition (CVD) and microwave plasma chemical vapor deposition (MPCVD) using various combination of binary catalysts with four transition metals such as Fe, Co, Cu, and Ni. In the preparation of CNTs from acetylene precursor by thermal CVD, the CNTs with very high yield of 43.6 % was produced over $Fe-Co/Al_2O_3$. The highest yield of CNTs was obtained with the catalyst reduced for 3 hr and the yield was decreased with increasing reduction time to 5 hr, due to the formation of $FeAl_2O_4$ metal-aluminate. On the other hand, the CNTs prepared by acethylene plasma CVD had more straight, smaller diameter, and larger aspect ratio(L/D) than those prepared by thermal CVD, although their yield had lower value of 27.7%. The degree of graphitization of CNTs measured by $I_d/I_g$ value and thermal degradation temperature were 1.04 and $602^{\circ}C$, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.311-316
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• 2002

Two different approaches, namely two-step deposition process and Bias-Enhanced Nucleation (BEN) technique have been examined for deposition of high quality diamond thin film on polycrystalline Ni which has low chemical activity with the carbon neutrals provided from the $CH_4/H_2$mixtures. A two-step deposition process, consisted of pre-deposition of soot layer at lower temperatures and subsequent deposition at higher temperature condition, has been developed to deposit diamond layer directly on Ni substrate. Diamond particles were observed after deposition step at $925^{\circ}C$ for 5 hours and those particles seem to be nucleated from the soot layer pre-deposited at lower temperatures ($810^{\circ}C$). Diamond particles of a substantial size were found on Ni substrate after biasing -220 V for 10 minutes and subsequent deposition for 2 hours while no diamond particles were observed under the conditions without applied bias.