• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1303-1304
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• 2006

본 연구에서는 ICP-CVD (inductively coupled plasma chemical vapor deposition)를 이용해 미세결정 실리콘 (nanocrystalline silicon thin film transistor, ns-Si TFT) 초기 성장 단계에 발생하는 비정질의 Incubation layer를 줄이기 위한 실험을 수행하였다. ICP-CVD를 사용하여 증착한 Si-rich $SiN_x$ Seed layer 상의 미세절정 실리콘의 성막조건을 알아보고 특성을 평가하였다. 미세결정 실리콘 박막은 Raman Spectroscopy를 이용해 분석하였다. 미세결정 실리콘의 초기 성장 단계에 발생하는 비정질 Incubation layer를 줄이기 위하여 Si-rich $SiN_x$를 Seed layer로 사용하는 것이 효과적임을 확인하였다. 또한 Si-rich $SiN_x$ 위에서의 미세결정 실리콘 표면 형태와 Seed 성장 기회의 관계를 알아보았다. 높은 전압의 수소 플라즈마 처리는 Seed 성장 기회를 늘이고, 박막의 결정화도를 높임을 확인하였다. 얇은 Incubation layer를 가지는 35nm 이하 두께의 미세결정 실리콘이 성공적으로 증착되었다. 본 연구 결과는 bottom 게이트 방식 박막 트랜지스터에 증착되는 미세결정 실리콘의 전기적 특성 향상에 유용할 것으로 판단된다.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1444-1445
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• 2006

Carbon nanotubes (CNTs) are grown on TiN-Coated silicon substrates at $700^{\circ}C$ using an ICP-CVD method. Ni catalysts for CNT growth are formed using an RF magnetron sputtering system. Post-treatment using hydrogen ions has been performed in the ICP reactor by varying the treatment period. The characterization using various techniques, such as FESEM, HRTEM, and Raman spectroscopy, show that the physical dimension as well as the crystal quality of CNTs are changed by the post-treatment process. It is also seen that the hydrogen ion-bombardment may change the surface structure of CNTs, which may lead to produce better electron emission properties. The physical reason for all the measured data obtained are discussed to establish the relationship between the structural property and the electron emission characteristic of CNTs.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1862-1864
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• 2005

Carbon nanotubes [CNTs] are grown on TiN-coated Si substrates at $700^{\circ}C$ by inductively coupled plasma-chemical vapor deposition (ICP-CVD). Pre-treatment of Ni catalysts has been performed using an RF magnetron sputtering system. Structural properties and field-emission characteristics of the CNTs grown are analyzed in terms of the RF power applied and the treatment time used in the pre-treatment process. The characterization using various techniques, such as FE-SEM, AFM, and Raman spectroscopy, show that the physical dimension as well as the crystal quality of CNTs are changed by pre-treatment of Ni catalysts. It is also seen that Ni catalysts with proper grain size and uniform surface roughness may produce much better electron emission. The physical reason for all the measured data obtained are discussed to establish the relationship between the structural property and the electron emission characteristic of CNTs.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1571-1573
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• 2003

Diamond films including nanocystalline and graphite phase are grown by microwave plasma chemical vapor deposition using $N_2$ additives and negative substrate bias at growth step. The microstructure of the films is controlled by changing $N_2$ gas ratio and negative bias. Defects and grain boundaries between diamond and graphite are proposed to be crucial factors for forming the conducting path of electron emissions. The effect of growth parameters on the film microstructure are investigated by Raman spectroscopy and scanning electron microscopy(SEM). Electron emission characteristics are also examined in terms of the film growth conditions.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1592-1594
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• 2003

This paper presents the deposition and characterization of microcrystalline silicon(${\mu}c$-Si:H) films by HWCVD(Hot-wire Chemical Vapor Deposition) method at low substrate($300^{\circ}C$). The filament temperature, pressure and $SiH_4$ concentration were determined to be a critical parameter for the deposition of poly-Si films. Series A was deposited under the conditions of $1380^{\circ}C$(Tf), 100 mTorr and $2{\sim}10%\{SC:SiH_4/(SiH_4+H_2)\}$ for 60 min. Series B was deposited under the conditions of $1400{\sim}1450^{\circ}(T_f)$, 30 mTorr and $2{\sim}12%$(SC) for 60 min. The physical characteristics were measured by Raman and FTIR spectroscopy, dark and photoconductivity measurements under AM1.5 illumination.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1595-1597
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• 2003

This paper presents the deposition of ${\mu}c$-Si:H thin-film and fabrication of a solar cell by VHF-PECVD method. The ${\mu}c$-Si:H thin films and pin-type solar cells are fabricated using multi-chamber cluster tool system. A 7.4% conversion efficiency was achieved from ${\mu}c$-Si:H thin film solar cells with total thickness less than $5{\mu}m$. The physical characteristic was measured by Raman spectroscopy, Solar cell characteristic was measured under AM1.5 illumination.

• Journal of Powder Materials
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• v.12 no.2 s.49
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• pp.146-150
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• 2005

An optimum route to synthesize $Al_2O_3$-based composite powders with homogeneous dispersion of carbon nanotubes (CNTs) was investigated. CNTs/Metal/$Al_2O_3$ nanocomposite powders were fabricated by thermal chemical vapor deposition of $C_2H_2$ gas over metal/$Al_2O_3$ nanocomposite catalyst prepared by selective reduction of metal oxide/$Al_2O_3$ powders. The FT-Raman spectroscopy analysis revealed that the CNTs have single- and multi-walled structure. The CNTs with the diameter of 25-43 nm were homogeneously distributed in the metal/$Al_2O_3$ powders, and their characteristics were strongly affected by a kind of metal catalyst and catalyst size. The experimental results show that the composite powder with required size and dispersion of CNTs can be realized by control of synthesis condition.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.160-161
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• 2015

탄소 원자들이 육각형의 벌집 모양으로 배열된 그래핀은 강철보다 200배 이상 강하며, 다이아몬드보다 2배 이상 열전도율이 높으며, 구리보다 100배 이상 전기가 잘 통하며, 실리콘보다 100배 이상 전자가 빠르게 움직일 수 있는 장점이 있다. 그래핀의 이러한 기계적, 열적, 전기적 특성은 에너지 밴드 갭이 없는 그래핀의 전자구조에서 근거하고 있다. 그러나 이러한 에너지 밴드 갭이 없는 그래핀은 반도체가 아닌 준금속의 특성을 보이며, 전자산업의 핵심소자인 트랜지스터로의 상용화에 큰 장벽이 되고 있다. 이러한 그래핀의 단점을 보완하고자 그래핀 이외의 2D 물질에 주목하기 시작하였으며, 그 가운데 최근 $MoS_2$과 같은 Transiton-Metal dichalcogenide(TMD)에 대한 관심이 급증하고 있다. TMD 중 대표적인 물질인 MoS2는 단일 층이 직접 전이 밴드 갭을 가진 반도체로서 전자회로와 발광 다이오드에 이용될 잠재적 가능성을 가진 재료이다. 본 연구에서는 이러한 MoS2 박막 형성을 하기 위해서 대면적이고 저비용으로 만들 수 있는 spin coating을 이용하려고 한다. spin coating을 이용하여 박막을 얻기 위해서는 좋은 wettability가 필수적이므로 이를 개선하기 위하여 용액, 전처리에 따른 wettability를 비교한 후, 열처리를 하여 그 표면을 관찰하고 Raman spectroscopy를 이용하여 분석하여 최적의 조건을 찾기 위한 실험을 하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1271-1272
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• 2007

Experimental results regarding to the structural properties of carbon nanotubes (CNTs) and the field-emission characteristics of CNT-coated tungsten (W) tips are presented. CNTs are successfully grown on conical-type W-tips by inductively coupled plasma-chemical vapor deposition (ICP-CVD) with or without inserting a TiN-buffer layer prior to the formation of Ni catalysts. For all the CNTs grown, their nanostructures, morphologies, and crystalline structures are analyzed by FESEM, HRTEM, and Raman spectroscopy. Furthermore, the emission properties of CNT-based field-emitters are characterized to estimate the maximum current density and the threshold voltage. The results obtained in this study indicate that the emission current level of the CNT-emitter without using a TiN buffer is desirable for the application of micro-focused x-ray systems.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.229-233
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• 2011

Diamond thin films were deposited on pretreated Co cemented tungsten carbide (WC-6%Co) inserts as substrate by microwave plasma chemical vapor deposition (MPCVD) system, equipped with a 915MHz, 30kW generator for generating a large-size plasma. The substrates were pretreated with two solutions Murakami solution $[KOH:K_3Fe(CN)_6:H_2O]$ and nitric solution $[HNO_3:H_2O]$ to etch, WC and Co at cemented carbide substrates, respectively. The deposition experiments were performed at an input power of 10 kW and in a total pressure of 100 torr. The influence of various $CH_4$ contents on the crystallinity and morphology of the diamond films deposited in MPCVD was investigated using scanning electron microscopy (SEM) and Raman spectroscopy. The diamond film synthesized by the $CH_4$ plasma shows a triangle-faceted (111) diamond. As $CH_4$ contents was increased, the thickness of diamond films increased and the faceted planes disappeared. Finally, Faceted diamond changed into nano-crystalline diamond with random crystallinity.