• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.2
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• pp.150-155
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• 2004

This study attempts to form a TiN barrier layer against Cu diffusion by the easier and more convenient method. In this new approach, Ti was sputter-deposited, and nitrided by heat-treating in the NH$_3$ambient. Sheet resistance of as-deposited Ti was 20 Ω/$\square$, but increased to 195 Ω/$\square$ after the heat-treatment at 30$0^{\circ}C$, and lowered to 120 Ω/$\square$ after the heat-treatment at 50$0^{\circ}C$, and $600^{\circ}C$. AES results for these thin films confirmed that the atomic ratio of Ti and N was close to 1:1 at or above 40$0^{\circ}C$ heat-treatment. However, it was also found that excessive oxygen was contained in the TiN layer. To examine the barrier property against Cu diffusion, 100nm Cu was deposited on the TiN layer and then annealed at 40$0^{\circ}C$ for 40 min.. Cu remained at the surface without diffusing into the Si layer.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.55-56
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• 2006

We investigated the diffraction grating efficiency by the DPSS laser beam wavelength to improve the diffraction efficiency on AsGeSeS & Ag/ AsGeSeS thin film. Diffraction efficiency was obtained from DPSS(532nm)(P:P)polarized laser beam on AsGeSeS, Ag/ AsGeSeS and AsGeSeS/Ag/AsGeSeS thin films. As a result, for the laser beam intensity, 0.24 mW, single AsGeSeS thin film shows the highest value of 0.161% diffraction efficiency at 300 s and for 2.4 mW, it was recorded with the fastest speed of 50 s, which the diffraction grating forming speed is faster than that of 0.24 mW beam. Ag/ AsGeSeS and AsGeSeS/ Ag/ AsGeSeS multi-layered thin film also show the faster grating forming speed at 2.4 mW and higher value of diffraction efficiency at 0.24 mW.

• Transactions on Electrical and Electronic Materials
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• v.8 no.4
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• pp.174-177
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• 2007

We fabricated organic field-effect transistors (OFETs) based a fluorinated copper phthalocyanine ($F_{16}CuPC$) and copper phthalocyanine (CuPc) as an active layer. And we observed the surface morphology of the $F_{16}CuPC$ thin film. The $F_{16}CuPC$ thin film thickness was 40 nm, and the channel length was $50{\mu}m$, channel width was 3 mm. And we also fabricated the $F_{16}CuPc/CuPc$ double layer FET and with different $F_{16}CuPc$ film thickness devices. We observed the typical current-voltage (I-V) characteristics and capacitance-voltage (C-V) in $F_{16}CuPc$ FET and we calculated the effective mobility. From the double layer FET devices, we observed the higher drain current more than single layer FET devices.

• Transactions on Electrical and Electronic Materials
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• v.12 no.4
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• pp.131-134
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• 2011

Back-end-of-line using ultra low-k (ULK; k < 2.5) has been required to reduce resistive capacitance beyond 45 nmtechnologies, because micro-processing units need higher speed and density. There are two strategies to manufacture ULK inter-layer dielectric (ILD) materials using an air-gap (k = 1). The former ULK and calcinations of ILD degrade the mechanical strength and induce a high cost due to the complication of following process, such as chemical mechanical polishing and deposition of the barrier metal. In contrast, the air-gap based low-k ILD with a relatively higher density has been researched on the trench-type with activity, but it has limited application to high density devices due to its high air-gap into the next metal layer. The height of air-gap into the next metal layer was reduced by changing to the via-typed air-gap, up to about 50% compared to that of the trench-typed air-gap. The controllable ULK was easily fabricated using the via-typed air-gap. It is thought that the via-type air-gap made the better design margin like via-patterning in the area with the dense and narrow lines.

• Advances in environmental research
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• v.4 no.1
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• pp.25-38
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• 2015

Wastewaters of textile industry cause high volume colour and harmful substance pollutions. Photocatalytic degradation is a method which gives opportunity of reduction of organic pollutants such as dye containing wastewaters. In this study, photocatalytic degradation of C.I. Basic Yellow 28 (BY28) as a model dye contaminant was carried out using Degussa P25 in a photocatalytic reactor. The experiments were followed out at three different azo dye concentrations in a reactor equipped UV-A lamp (365 nm) as a light source. Azo dye removal efficiencies were examined with total organic carbon and UV-vis measurements. As a result of experiments, maximum degradation efficiency was obtained as 100% at BY28 concentration of $50mgL^{-1}$ for the reaction time of 2.5 h. The photodegradation of BY28 was described by a pseudo-first-order kinetic model modified with the langmuir-Hinshelwood mechanism. The adsorption equilibrium constant and the rate constant of the surface reaction were calculated as $K_{dye}=6.689{\cdot}10^{-2}L\;mg^{-1}$ and $k_c=0.599mg\;L^{-1}min^{-1}$, respectively.

• Advances in nano research
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• v.8 no.2
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• pp.95-102
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• 2020

In this work the properties of iron oxide magnetic nanoparticles (MNPs) synthesized by electrochemical method using different water-alcohol proportions and alcohols have been investigated. The syntheses were carried out using 99% iron foils acting electrodes in a 0.04 M NaCl solutions at room temperature applying 22 mAcm^-2 on the working electrode, mostly obtaining magnetite nanoparticles. The impact of the electrolyte in the size of the synthesized MNPs has been evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), chronopotentiometric studies, and magnetic characterization. The results have shown that nanoparticles can be obtained in the range of 6 to 26 nm depending on the type of alcohol and the proportions in the mixture of water-alcohol. The same trend has been observed for all alcohols. As the proportion of these in the medium increases, the nanoparticles obtained are smaller in size. This trend is maintained until a certain proportion of alcohol: 50% for methanol, and 60% for the rest of alcohols, proportions where obtaining a single phase of magnetite is not favored.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.240-245
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• 2004

Tensile properties of hard coating material, TiN, were evaluated using micro-tensile testing system. TiN has been known as a hard coating material commonly used today. Micro-tensile testing system consisted of a micro tensile loading system and a micro-ESPI(Electronic Speckle Pattern Interferometry) system. Micro-tensile loading system had a maximum load capacity of 500mN and a resolution of 4.5 nm in stroke. TiN thin film $1{\mu}m$ thick was deposited on the Si wafer pre-deposited of $Si_3N_4$ film substrate by the closed field unbalanced magnetron sputtering (CFUBMS) process. Three kinds of micro-tensile specimen with the respective width of $50{\mu}m$, $100{\mu}m$ and $500{\mu}m$ were fabricated by MEMS process. The mechanical properties including tensile strength and elastic modulus were determined using the micro-tensile testing system and compared by those obtained by nano-indentation

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.7
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• pp.637-644
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• 2009

We have analyzed the biomechanical characteristics of cervical spine after total disc replacement using finite element analysis. A finite element model of C2-C7 spinal motion segment was developed and validated by other experimental studies. Two types of artificial discs, semi-constraint and un-constraint, were inserted at C6-C7 segments. Inferior plane of C7 vertebra was fixed and 1Nm of moment were applied on superior plane of C2 vertebra with 50N of compressive load along follower load direction. Mobility of the cervical spine in which each artificial disc inserted was higher than that of intact one in all loading conditions. Also, high mobility at the surgical level after total disc replacement could lead higher facet joint force and ligaments axial stresses. The results of present study could be used to evaluate surgical option and validate the biomechanical characteristics of the implant in total disc replacement in cervical spine.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.85-90
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• 2002

$RuO_2$/GaN and related contacts were investigated for Schottky contacts in GaN-Based optical and electronic devices. We demonstrated that an $RuO_2$ film forms a stable Schottky contact on a GaN layer with a barrier height (${\Phi}_B$) of 1.46 eV and transmittance of 70% in the visible and near UV region. $RuO_2$/GaN Schottky diode showed a breakdown at over -50V and leakage current of only 0.3 nA at -5V. The $RuO_2$/GaN Schottky type photodetector had the UV/Visible rejection ratio of over $10^5$ and the responsivity of 0.23 A/W at 330 nm. The $RuO_2$ gate AlGaN/GaN EFET exhibited high drain current ($I_d$) of 689.3 mA/mm and high transconductance ($g_m$) of 197.4 mS/mm. Cut-Off frequency ($f_t$) and maximum operating frequency ($f_{max}$) were measured as 27.0 GHz and 45.5 GHz, respectively.

• The Korea Journal of Herbology
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• v.23 no.3
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• pp.67-72
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• 2008

Objectives : This study presents a high performance liquid chromatography methods for the quantitative and qualitative analysis of rosmarinic acid (RA) and caffeic acid (CA) in Perilla frutescens var. japonica and var. acuta. Methods : Chromatographic separation was performed using a mixture of methanol, water and formic acid (35 : 64.2 : 0.8) with a reversed-phase column (Gemini C18, 4.6 ${\times}$ 150 mm, 3 ${\mu}m$). The analyses were detected at UV (280 nm). Results : The samples were extracted with 50% EtOH under reflux for 1 h, and simultaneous determination for RA and CA in hyang-so-san and haeng-so-san was possible without interference peaks Conclusions : According the results, we developed a determination method for RA and CA in Perillae Folium. Owing to Perilla frutescens var. japonica and var. acuta did not show significant difference in contents of RA and CA, both Perilla frutescens could be available as herbal medicine.