• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.38-39
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• 2006

We present experimental results that regard the effects of catalyst preparation on the structural and field-emissive properties of CNTs. The CNTs used in this research have been synthesized using the inductively coupled plasma-chemical vapor deposition (ICP-CVD) method. Catalyst materials (such as Ni, Co, and Invar 426) are varied and deposited on buffer films by RF magnetron sputtering. Prior to growth of CNTs, $NH_3$ plasma etching has also been performed with varying plasma etching time and power. For all the CNTs grown, nanostructures and morphologies are analyzed using Raman spectroscopy and FESEM, in terms of buffer films, catalyst materials, and pre-treatment conditions. Furthermore, the field electron-emission of CNTs are measured and characterized in terms of the catalyst preparation environments. The CNTs grown on Nicatalyst layer would be more effectual for enhancing the growth rate and achieving the vertical-alignment of CNTs rather than other buffer materials from results of SEM study. The crystalline graphitic structure of CNTs is improved as the catalyst dot reaches a critical size. Also, the field-emission result shows that the CNTs using Ni catalyst would be more favorable for improving electron-emission capabilities of CNTs compared with other samples.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.303-310
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• 2008

We fabricated hydrogenated amorphous silicon(a-Si:H) 140 nm thick film on a $180\;nm-SiO_2/Si$ substrate with an inductively-coupled plasma chemical vapor deposition(ICP-CVD) equipment at $250^{\circ}C$. Moreover, 30 nm-Ni film was deposited with a thermal-evaporator sequently. Then the film stack was annealed to induce silicides by a rapid thermal annealer(RTA) at $200{\sim}500^{\circ}C$ in every $50^{\circ}C$ for 30 minuets. We employed a four-point tester, high resolution X-ray diffraction(HRXRD), field emission scanning electron microscope(FE-SEM), transmission electron microscope(TEM), and scanning probe microscope(SPM) in order to examine the sheet resistance, phase transformation, in-plane microstructure, cross-sectional microstructure evolution, and surface roughness, respectively. We confirmed that nano-thick high resistive $Ni_3Si$, mid-resistive $Ni_2Si$, and low resistive NiSi phases were stable at the temperature of <300, $350{\sim}450^{\circ}C$, and >$450^{\circ}C$, respectively. Through SPM analysis, we confirmed the surface roughness of nickel silicide was below 12 nm, which implied that it was superior over employing the glass and polymer substrates.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1597-1599
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• 2004

Carbon nanotubes (CNTs) are grown on the TiN-coated silicon substrate by varying the thickness of Ni and Invar426 catalyst layers at 600$^{\circ}C$ using an inductively coupled plasma-chemical vapor deposition (ICP-CVD). The Ni and Invar426 catalysts are formed using an RF magnetron sputtering system with various deposition periods. Characterization using various techniques, such as FESEM, HRTEM, and Raman spectroscopy, shows that the physical dimension as well as the crystal quality of grown CNTs are strongly changed by the kind and thickness of catalyst materials. It is also seen that Ni catalysts would be more desirable for vertical-alignment of CNTs compared with Invar426 catalysts. However, the CNTs using Invar426 catalysts display much better electron emission capabilities than those using Ni catalysts. The physical reason for all the measured data obtained are discussed to establish the relationship between structural properties and field-emissive properties of CNTs.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1270_1271
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• 2009

In this research, gallium-incorporated zinc oxide (ZnO:Ga) thin films have been used as a coating material for enhancing the field-emission property of CNT-emitters. Multi-walled CNTs were directly grown on conical-type ($250{\mu}m$ in diameter) metal-tip substrates at $700^{\circ}C$ by inductively coupled plasma-chemical vapor deposition (ICP-CVD). The pulsed laser deposition (PLD) technique was used to produce 5wt% gallium-doped ZnO (5GZO) films with very low stress. The structural properties of ZnO and 5GZO coated CNTs were characterized by Raman spectroscopy. Field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) were also used to monitor the variation in the morphology and microstructure of CNTs before and after 5GZO-coating. The measurement of the field emission characteristics showed that the emitter that coated the 5GZO (10nm) on CNTs exhibited the best performance: a maximum emission current of $325{\mu}A$, a threshold field of 2.2 V/${\mu}m$.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1462-1464
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• 2006

Scaling rules for TFT application devices have led to the necessity of ultra thin dielectric films and high-k dielectric layers. In this paper, The advantages of high concentration of nitrogen in silicon oxide layer deposited by using $N_2O$ in Inductively Coupled Plasma Chemical Vapor Deposition (ICP-CVD) is investigated using X-ray energy dispersive spectroscopy (EDS). We have reported about Ellipsometric measurement, Capacitance - Voltage characterization and processing conditions.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1533-1535
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• 2002

Carbon nanotubes (CNTs) were grown with high density on a large area of Ni-coated silicon oxide substrates by using an inductively coupled plasma-chemical vapor deposition (ICP-CVD) of $C_2H_2$ at temperatures ranging from 600 to $700^{\circ}C$. The Ni catalyst was formed using an RF magnetron sputtering system with varying the operating pressure and exposure time of $NH_3$ plasma. The surface morphology of nickel catalyst films and CNTs was examined by SEM and AFM. The graphitized structure of CNTs was confirmed by Ramman spectra, SEM, and TEM. The growth of CNTs was observed to be strongly influenced by the surface morphology of Ni catalyst, which depended on the pre-treatment time and growth temperature. Dense CNTs with uniform-sized grains were successfully grown by ICP-CVD.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.386-387
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• 2007

ICP-CVD(Inductively Coupled Plasma-Chemical Vapor Deposition)를 이용하여 플라즈마 처리에 따른 Al이 도핑된 ZnO(AZO) 박막의 표면 부착력과 굴절율, 표면거칠기에 관한 연구를 하였다. 플라즈마 처리는 인가전압, 시간을 변수로 하였고 반응 가스는 Ar을 사용하였다. 표면조성은 AFM, 광학적 특성은 UV-Vis 분광계를 이용한 광투과도 측정으로부터 굴절률과 밴드갭을 조사하였고 표면 부착력은 접촉각 분석기(제조사:Kruss)를 사용하여 조사하였다. 플라즈마 처리 시간이 길어짐에 따라 박막 표면의 거칠기가 커지고 부착력은 증가하는 것으로 나타났다.

• Journal of the Korean Vacuum Society
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• v.21 no.4
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• pp.212-218
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• 2012

The optical properties of AZO thin films prepared by the RF mangnetron sputtering system was studied to research the dependance of chemical properties of substrate. The substrate was the SiOC film deposited by Inductively coupled plasma chemical vapor deposition with various gas flow rate of $O_2$ and Ar (DMDMOS). In accordance with the increase of Ar gas flow rates, the Si-O bond in the SiOC film increased and then progressed the amorphism. The roughness of AZO grown on SiOC film with high degree of amorphism decreased and then improved the flatness of surfaces. Moreover, the ultra violet emission with high intensity was spontaneously induced in the AZO film growed on SiOC film with high degree of amorphism.

• Korean Journal of Materials Research
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• v.15 no.10
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• pp.626-631
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• 2005

GaN-related compound semiconductors were grown on the corrugated interface substrate using a metalorganic chemical vapor deposition system to increase the optical power of white LEDs. The patterning of substrate for enhancing the extraction efficiency was processed using an inductively coupled plasma reactive ion etching system and the surface morphology of the etched sapphire wafer and that of the non-etched surface were investigated using an atomic force microscope. The structural and optical properties of GaN grown on the corrugated interface substrate were characterized by a high-resolution x-ray diffraction, transmission electron microscopy, atomic force microscope and photoluminescence. The roughness of the etched sapphire wafer was higher than that of the non-etched one. The surface of III-nitride films grown on the hemispherically patterned wafer showed the nano-sized pin-holes that were not grown partially. In this case, the leakage current of the LED chip at the reverse bias was abruptly increased. The reason is that the hemispherically patterned region doesn't have (0001) plane that is favor for GaN growth. The lateral growth of the GaN layer grown on (0001) plane located in between the patterns was enhanced by raising the growth temperature ana lowering the reactor pressure resulting in the smooth surface over the patterned region. The crystal quality of GaN on the patterned substrate was also similar with that of GaN on the conventional substrate and no defect was detected in the interface. The optical power of the LED on the patterned substrate was $14\%$ higher than that on the conventional substrate due to the increased extraction efficiency.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.198-198
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• 2011

단분산 결정질 실리콘 나노입자 (<10 nm)는 양자점 효과로 인한 선택적 파장 흡수가 가능하므로 태양전지 분야에 응용 가능성이 크다. 특히 입경의 크기가 작아지면 부피대비 표면적이 넓어지기 때문에 태양빛 흡수 면적이 증가한다. 따라서 입자의 크기는 태양전지에서 효율을 결정하는 중요한 요소 중 하나이다. 이러한 이유에서 plasma arc synthesis, laser ablation, pyrolysis 그리고 PECVD (Plasma Enhanced Chemical Vapor Deposition) 등이 실리콘 나노입자를 합성하는데 연구되어 왔으며, 특히 PECVD는 입자 생성과 동시에 균일한 증착이 이루어질 수 있기 때문에 태양전지 제작 시 공정 효율을 높일 수 있다. PECVD를 이용한 나노입자 합성에서 입경을 제어하는데 중요한 전구물질은 Ar과 SiH4가스이다. Ar 가스는 ICP (Inductively Coupled Plasma) 챔버 내부에 가해준 전력을 통해 가속됨으로써 분해되어 Ar plasma가 생성된다. 이는 공급되는 SiH4가스를 분해시켜 핵생성을 유도하고, 그 주위로 성장시킴으로써 실리콘 나노입자가 합성된다. 이때 중요한 변수 중 하나는 핵생성과 입자성장시간의 조절을 통한 입경제어 이다. 또한 공급되는 가스의 유량은 입자가 생성될 때 필요한 화학적 구성비를 결정하므로 입경에 중요한 요소가 된다. 마지막으로 공정압력은 챔버내부의 plasma 구성 요소들의 평균 자유 행로를 결정하여 SiH4가 분해되어 입자가 생성되는 속도와 양을 제어한다. PECVD를 이용한 실리콘 나노입자 형성의 주요 변수는 RF pulse, 가스(Ar, SiH4, H2)의 유량, Plasma power, 공정압력 등이 있다. 본 연구에서는 RF (Radio Frequency) PECVD방법을 이용하여 실리콘 나노입자를 만드는데 필요한 여러 변수들을 제어함으로써 이에 따른 입경분포 차이를 연구하였다. 또한 SEM (Scanning Electron Microscopy)과 SMPS (Scanning Mobility Particle Sizer)를 이용하여 각 변수에 따라 생성된 나노입자의 입경과 농도를 분석하였다. 이 중 plasma power에 따른 입경분포 측정 결과 600W에서 합성된 실리콘 나노입자가 상당히 단분산 된 형태로 나타남을 확인할 수 있었고 향후 다른 변수의 제어, 특히 DC bias 전압과 열을 가함으로써 나노입자의 결정성을 확인하는 추가 연구를 통해 태양전지 제작에 응용 할 수 있을 것으로 예상된다.