• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.433-433
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• 2013

Graphene, $sp^2$-hybridized 2-Dimension carbon material, has drawn enormous attention due to its desirable performance of excellent properties. Graphene can be applied for many electronic devices such as field-effect transistors (FETs), touch screen, solar cells. Furthermore, indium tin oxide (ITO) is commercially used and sets the standard for transparent electrode. However, ITO has certain limitations, such as increasing cost due to indium scarcity, instability in acid and basic environments, high surface roughness and brittle. Due to those reasons, graphene will be a perfect substitute as a transparent electrode. We report the graphene synthesized by inductive coupled plasma enhanced chemical vapor deposition (ICP-PECVD) process on Cu substrate. The growth was carried out using low temperature at $400^{\circ}C$ rather than typical chemical vapor deposition (CVD) process at $1,000^{\circ}C$ The low-temperature process has advantage of low cost and also low melting point materials will be available to synthesize graphene as substrate, but the drawback is low quality. To improve the quality, the factor affect the quality of graphene was be investigated by changing the plasma power, the flow rate of precursors, the scenario of precursors. Then, graphene film's quality was investigated with Raman spectroscopy and sheet resistance and optical emission spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.2056-2060
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• 2007

A successful combination of “oxygen-assisted chemical vapor deposition (CVD) process” and Co catalyst nanoparticles to grow highly pure single walled carbon nanotubes (SWNTs) was demonstrated. Recently, it was reported that addition of small amounts of oxygen during CVD process dramatically increased the purity and yield of carbon nanotubes. However, this strategy could not be applied for discrete Fe nanoparticle catalysts from which appropriate yields of SWNTs could be grown directly on solid substrates, and fabricated into field effect transistors (FETs) quite efficiently. The main reason for this failure is due to the carbothermal reduction which results in SiO2 nanotrench formation. We found that the oxygen-assisted CVD process could be successfully applied for the growth of highly pure SWNTs by switching the catalyst from Fe to Co nanoparticles. The topological morphologies and p-type transistor electrical transport properties of the grown SWNTs were examined by using atomic force microscope (AFM), Raman, and from FET devices fabricated by photolithography.

• Journal of the Optical Society of Korea
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• v.16 no.3
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• pp.313-317
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• 2012

We have evaluated a 1.3 ${\mu}m$ vertical-cavity surface-emitting laser (VCSEL), whose bottom mirror and central active layer were grown by metal organic chemical vapor deposition (MOCVD) and whose top mirror was covered with a dielectric coating, for 10 Gb/s data transmission over single-mode fibers (SMFs). Successful demonstration of error-free transmission of the directly modulated VCSEL signals at data rate of 10 Gb/s over a 10 km-long SMF was achieved for operating temperatures from $20^{\circ}C$ to $60^{\circ}C$ up to bit-error-rate (BER) of $10^{-12}$. The DC bias current and modulation currents are only 7 mA and 6 mA, respectively. The results indicate that the VCSEL is a good low-power consuming optical signal source for 10 GBASE Ethernet applications under controlled environments.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.113-120
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• 2007

Chemical vapor deposition (CVD) is one of the various synthesis methods that have been employed for carbon nanotube (CNT) growth. In particular, Ren et al reported that large areas of vertically aligned multi-wall carbon nanotubes could be grown using a direct current (dc) PECVD system. The synthesis of CNT requires a metal catalyst layer, etchant gas, and a carbon source. In this work, the substrates consists of Si wafers with Ni-deposited film. Ammonia $NH_3$) and acetylene ($C_2H_2$) were used as the etchant gases and carbon source, respectively. Pretreated conditions had an influence on vertical growth and density of CNTs. And patterned growth of CNTs could be achieved by lithographical defining the Ni catalyst prior to growth. The length of single CNT was increased as niclel dot size increased, but the growth rate was reduced when nickel dot size was more than 200 nm due to the synthesis of several CNTs on single Ni dot. The morphology of the carbon nanotubes by TEM showed that vertical CNTs were multi-wall and tip-type growth mode structure in which a Ni cap was at the end of the CNT.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.538-546
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• 2006

We report on characteristics of specially designed inductively-coupled-plasma chemical vapor deposition (ICP-CVD) system for top-emitting organic light emitting diodes (TOLEDs). Using high-density plasma on the order of $10^{11}$ electrons/$cm^3$ generated by linear-type antennas connected in parallel and specially designed substrate cooling system, a 100 nm-thick transparent $SiN_{x}$ passivation layer was deposited on thin Mg-Ag cathode layer at substrate temperature below $50\;^{\circ}C$ without a noticeable plasma damage. In addition, substrate-mask chucking system equipped with a mechanical mask aligner enabled us to pattern the $SiN_x$ passivation layer without conventional lithography processes. Even at low substrate temperature, a $SiN_x$ passivation layer prepared by ICP-CVD shows a good moisture resistance and transparency of $5{\times}10^{-3}g/m^2/day$ and 92 %, respectively. This indicates that the ICP-CVD system is a promising methode to substitute conventional plasma enhanced CVD (PECVD) in thin film passivation process.

• Carbon letters
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• v.18
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• pp.37-42
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• 2016

Graphene was grown on molybdenum (Mo) foil by a chemical vapor deposition method at different growth temperatures (1000℃, 1100℃, and 1200℃). The properties of graphene were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and Raman spectroscopy. The results showed that the quality of the deposited graphene layer was affected by the growth temperature. XRD results showed the presence of a carbide phase on the Mo surface; the presence of carbide was more intense at 1200℃. Additionally, a higher I_2D/I_G ratio (0.418) was observed at 1200℃, which implies that there are fewer graphene layers at this temperature. The lowest I_D/I_G ratio (0.908) for the graphene layers was obtained at 1200℃, suggesting that graphene had fewer defects at this temperature. The size of the graphene domains was also calculated. We found that by increasing the growth temperature, the graphene domain size also increased.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.593-597
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• 2005

FIB equipment can perform sputtering and chemical vapor deposition simultaneously. It is very advantageously used to fabricate a micro structure part having 3D shape because the minimum beam size of ${\phi}$ 10nm and smaller is available. Currently FIB is not being applied in the fabrication of this micro part because of some problems to redeposition and charging effect of the substrate causing reduction of accuracy with regards to shape and productivity. Furthermore, the prediction of the material removal rate information should be required but it has been insufficient for micro part fabrication. The paper have the targets that are FIB-CVD characteristic analysis and minimum line pattern resolution achievement fur 3D micro fabrication. We make conclusions with the analysis of the results of the experiment according to beam current, pattern size and scanning parameters. CVD of 8 pico ampere shows superior CVD yield but CVD of 1318 pico ampere shows the pattern sputtered. And dwell time is dominant parameter relating to CVD yield.

• Journal of Mechanical Science and Technology
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• v.19 no.6
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• pp.1329-1337
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• 2005

The OLED (Organic Light Emitting Diodes) display recently used for the information indicating device has many advantages over the LCD (Liquid Crystal Display), and its demand will be increased highly. The linear cell should be designed carefully considering the uniformity of thin film on the substrate. Its design needs to compute the temperature field analytically because the uniformity for the thin film thickness depends on the temperature distribution of the source (organic material). In the present study, the design of the linear cell will be modified or improved on the basis of the temperature profiles obtained for the simplified linear cell. The temperature distributions are numerically calculated through the STAR-CD program, and the grids are generated by means of the ICEM CFD program. As the results of the simplified linear cell, the temperature deviation was shown in the parabolic form among the both ends and the center of the source. In order to reduce the temperature deviation, the configuration of the rectangular ends of the crucible was modified to the circular type. In consequence, the uniform temperature is maintained in the range of about 90 percent length of the source. It is expected that the present methods and results on the temperature analysis can be very useful to manufacture the vapor deposition device.

• Bulletin of the Korean Chemical Society
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• v.15 no.1
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• pp.79-83
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• 1994

The organometallic chemical vapor deposition of single precursors, $[Me_2Al({\mu}-NHR)]_2\;(R=^iPr,\;^tBu)$, for alumininum nitride thin films has been investigated to evaluate their poroperties as potential precursors. In chemical vapor deposition processes the gas phase products scattered from a Ni(100) substrate were analyzed by mass spectrometry and the deposited films were characterized by X-ray photoelectron spectroscopy (XPS). The optimum temperatures for the formation of AlN films have been found to be between 700 K and 800 K. Carbon contamination of the films seems to be attributed mainly to the methyl groups bonded to the aluminum atoms. It is apparent that $^tBu$ group is better than $^iPr$ group as a substituent on the nitrogen atom of the single precursors for the AlN thin film formation.

• Korean Journal of Metals and Materials
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• v.49 no.12
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• pp.945-949
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• 2011

The cycling characteristics of $MgH_2$ made by hydriding chemical vapor deposition method have been investigated. The particle size of $MgH_2$ made by HCVD was about $1{\mu}m$. The cycling experiment was performed by measuring hydrogen quantity absorbed at 673 K and under 35 atm of hydrogen pressure for 30 min. Up to 3 cycles the hydrogen storage capacity increased, but from 4 to 6 cycles the hydrogen storage capacity decreased rapidly. During this cycling test the particle size increased gradually from $1{\mu}m$ to $6{\mu}m$. This increase was due to sintering by the high reaction temperature and the heat of reaction during hydrogen absorption. From 7 to 30 cycles, the hydrogen storage capacity was maintained at 5.8 wt%. Even after 30 cycles, the plateau pressure was constant.