• Journal of the Korean Society for Heat Treatment
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• v.33 no.3
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• pp.124-128
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• 2020

Recently, many studies on growth of single crystal diamond using MPECVD have been conducted. The heteroepitaxial method is one of the methods for growing diamonds on a large-area substrate, and research on synthesis of single crystal diamonds using SrTiO₃, MgO, and sapphire substrates has been attempted. In addition, research is being conducted to reduce the internal stress generated during diamond growth and to improve the crystallinity of the diamond. The compressive stress generated therein causes peeling and bowing from the substrate. This study aimed to synthesize heteroepitaxial single crystal diamonds with high crystallinity by surface modification. A diamond thin film was first grown on a sapphire/Ir substrate by MPECVD, and then etched with H₂ gas to modified the morphology and roughness of the surface. A secondary diamond layer was grown on the surface, and the internal stress, crystallinity of the diamond were investigated. As a result, the fabrication of single crystal diamonds with improved crystallinity was confirmed.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.390-393
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• 1989

Diamond is synthesized from the gaseous mixture of carbon monoxide and hydrogen by microwave PECVD. $10{\times}10mm^2$ silicon wafers are used as the substrate,and it can be raised more than $900^{\circ}C$ by microwave absorption, radiation by plasma and bombardment of ions. The changes of the morphology and the growth rates of the deposits with the experimental conditions are examined by Scanning Electron Microscopy. The d values of all the deposited films concide with those of powder diffraction data in XRD. In Raman spectra, the peak of the deposit coincides with that of the natural diamond which has a value of 1332.5 $cm^{-1}$, and the broad peak from 1360 $cm^{-1}$to 1600 $cm^{-1}$which represents the amorphous graphite was observed in the higher concentration of carbon monoxide.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.501-506
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• 2006

Carbon nanotubes (CNTs) were grown with a microwave plasma enhanced chemical vapor deposition (MPECVD) method, which has been regarded as one of the most promising candidates for the synthesis of CNTs due to the vertical alignment, the low temperature and the large area growth. MPECVD used methane ($CH_4$) and hydrogen ($H_2$) gas for the growth of CNTs. 10 nm thick Ni catalytic layer were deposited on the Ti coated Si substrate by RF magnetron sputtering method. In this work, the pretreatment was that the Ni catalytic layer in different microwave power (600, 700, and 800 W). After that, CNTs deposited on different pressures (8, 12, 16, and 24 Torr) and grown same microwave power (800 W). SEM (Scanning electron microscopy) images showed Ni catalytic layer diameter and density variations were dependent with their pretreatment conditions. Raman spectroscopy of CNTs shows that $I_D/I_G$ ratios and G-peak positions vary with pretreatment conditions.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1440-1441
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• 2006

In this study, we synthesized CNTs(carbon nanotubes) on the glass substrate by microwave plasma enhanced chemical vapor deposition (MPECVD), Effect of bias voltage on the grown behavior and morphology of CNTs were investigated. Recently, it has been proposed that aligned CNTs can also be achieved by the application of electric bias to the substrate during growth, the first time reported the bias effect such that the nanotube alignment occurred only when a positive bias was applied to the substrate whereas no aligned growth occurred under a negative bias and no tube growth was observed without bias. On the country, several researchers reported some different observations that aligned nanotubes could also be grown under negative substrate biases. This discrepancy as for the effect of positive and negative bias may indicate that the bias effect is not fully understood yet. The glass and Si wafers were first deposited with TiN buffer layer by r.f sputtering method, and then Ni catalyst same method, The thickness of TiN and Ni layer were 200 nm and 60 nm, respectively. The main process parameters include the substrate bias (0 to - 300 V), and deposition pressure (8 to 20 torr).

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.833-840
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• 1996

Diamond thin films were deposited on p-type (100) Si wafers using MPECVD. Prior to deposition, ultrasonic striking was done to improve density of nucleation sites with dimond powder of 40~$60\mu$m size. Then diamond thin films were deposited at $^900{\circ}C$, 40Torr and 1000W microwave power using ${CH}_{4}$ and ${H}_{2}$ gases. The purity, the morphology and the microstructur'e and microdefects of diamond thin films were characterized by Raman spectroscopy, SEM and TEM, repectively. In Raman spectroscopy the peaks of non-diamond phase increased as ${CH}_{4}$, concentration increased. In SEM, the morphology of diamond thin films varied from crystalline to cauliflower as ${CH}_{4}$, concentration increased. As ${CH}_{4}$ con centration increased, the density of defects increased, with most defects being {III} twin. ${MTP}_{5}$, were formed with five (II]) planes. As these (Ill) Planes were twinned, ${MTP}_{5}$, represented five-fold symmetry. ]n the interfaces, defects in diamond thin films fanned out from small regions implying nucleation sites.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.42-42
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• 2003

Ni/Si 기판상에 CH$_4$, H$_2$, $N_2$의 혼합기체를 사용하여 $700^{\circ}C$에서 5분 동안 MPECVD법으로 탄소나노튜브 성장시켰다. 이 과정에서 CH$_4$, H$_2$에 대한 $N_2$의 유량비를 여러 가지 값으로 변화시켜 그 성장 양상을 살펴보았다. 혼합기체 내 질소의 함량에 따라 나노튜브의 성장길이와 quality가 달라짐을 SEM과 Raman spectroscopy 측정을 통하여 확인하였다. 나노튜브의 성장 시 혼합기체 내 주입하는 질소량에 의해 나노튜브의 성장길이가 변화됨을 SEM을 통해 관찰할 수 있었고 혼합기체 내 질소의 비율이 커질수록 carbonaceous particle 등의 감소로 인한 나노 튜브의 quality가 향상됨을 Raman spectra를 통해 확인할 수 있었다. 또한 TEM과 SEM 관찰을 통해 성장된 탄소나노튜브가 대나무(bamboo) 구조를 가진 수직 배향된 다중벽 탄소나노튜브임을 확인하였다.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.337-350
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• 1999

Thick diamond film having ~700${\mu}{\textrm}{m}$ thickness was deposited on polycrystalline molybdenum (Mo) substrate using high power (4kW) microwave plasma enhanced chemical vapor deposition (MPECVD) system. We could achieve free-standing diamond film via detaching as-deposited diamond film from the substrate by rapid cooling them under vacuum. We investigated the variation of photoconductivity after exposing the film surface to either oxygen or hydrogen plasma. At as-grown state, the growth side (the as-grown surface of the film) showed noticeable photoconductivity. The oxygen plasma treatment of this side led to the insulator. After exposing the film surface to hydrogen plasma, on the other hand, we could observe the reappearing of photoconductivity at the growth side. Based on these results, we suggest that the hydrogen plasma treatment may enhance the photoconductivity of free-standing diamond film.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.441-445
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• 1999

Thick diamond film having $~700\mu\textrm{m}$ thickness was deposited on polycrystalline molybdenum(Mo) substrate using high power (4 kW) microwave plasma-enhanced chemical vapor depostion (MPECVD) system. We could achieve free-standing diamond film via detaching as-deposited diamond film from the substrate by rapid cooling them under vacuum. We investigated the variation of photoconductivity after exposing the film surface to either oxygen or hydrogen plasma. At as-grown state, the growth side (the as-grown surface of the film) showed noticeable photoconcuctivity. The oxygen plasma treatment of this side led to the insulator. After exposing the film surface to hydrogen plasma, on the other hand, we could observe the reappearing of photoconductivity at the growth side. Based on these results, we suggest that the hydrogen plasma treatment may enhance the photoconductivity of free-standing diamond film.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.73-74
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• 2006

Carbon nanotubes (CNTs) have recently attracted great attention because of their excellent physical properties, such as high mechanical strength, thermal stability, and electronic properties. These useful properties of carbon nanotubes make themselves good candidates for various application field, such as a transistor, battery, field emission display, nanoscale inter-connects, and so on. Gas-phase techniques offer the unique ability to synthesize well-oriented arrays of CNTs. However, it is seldom reported that the pressure influences on the growth of CNTs under low substrate temperature. In this work, the effect of the working pressure and the influence of the catalyst preparation on the properties of CNTs grown by microwave plasma chemical vapor deposition (MPCVD) were investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.373-376
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• 1997

Diamond thin films were deposited on P-type(100) Si wafers using MPECVD. Prior to deposition, mechanical scretching was done to improve density of nucleation sites with diamond paste of 0.25${\mu}{\textrm}{m}$ size. Diamond films were deposited under the following conditions : methane concentration of 0.5~5%, oxygen concentration of 0~70%, process pressure of 70Torr, process temperature of 900~95$0^{\circ}C$, and deposition time 5hrs. The changes of the morphology and the growth rates of the deposits with the experimental conditions are expriend by Scanning Electron Microscopy. Raman Spectroscopy and X-ray Diffraction method.