• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.959-961
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• 1999

ZnO thin films are deposited by using an RF magnetron sputtering system. Structural and electrical properties are analyzed as a function of deposition conditions, such as RF power, Ar/($Ar+O_2$) ratio, and substrate temperature. The c-axial growth of ZnO is observed to be preferable to the $SiO_2$/Si substrate, rather than the Si substrate. By adding the oxygen gas during deposition, the electrical resistivity of films is increased, but the c-axial growth is inhibited. A pizoelectric resonator of Al/ZnO/Al is also fabricated to estimate the electric-mechanical coupling coefficient($k^2$) of ZnO film. The value of $k^2$ obtained from our work is about 10.14 %.

• Journal of Korea Foundry Society
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• v.17 no.3
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• pp.245-251
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• 1997

Solderability, interfacial reaction and mechanical properties of joint between Sn-Bi-Ag base solder and Cu-substrate were studied. Solders were subjected to aging treatments to see the change of mechanical properties for up to 30 days at $100^{\circ}C$, and then also examined the changes of microstructure and morphology of interfacial compound. Sn-Bi-Ag base solder showed about double tensile strength comparing to Pb-Sn eutectic solder. Addition of 0.7wt%Al in the Sn-Bi-Ag alloy increase spread area on Cu substrate under R-flux and helps to reduce the growth of intermetallic compound during heat-treatment. According to the aging experiments of Cu/solder joint, interfacial intermetallic compound layer was exhibited a parabolic growth to aging time. The result of EDS, it is supposed that the soldered interfacial zone was composed of $Cu_6Sn_5$.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1379-1382
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• 1997

Diamond-like carbon(DLC) thin films are produced by using a filtered cathodic vacuum arc(FCVA) deposition system. Different magnetic components, namely steering, focusing, and filtering plasma-optic systems, are used to achieve a stable arc plasma and to prevent the macroparticles from incorporating into the deposited films. Effects of magnetic fields on plasma behavior and film deposition are examined. The carbon ion energy is found to be varied by applying a negative (accelerating) substrate bias voltage. The deposition rate of DLC films is dependent upon magnetic field as well as substrate bias voltage and at a nominal deposition condition is about $2{\AA}/s$. The structural properties of DLC films, such as internal stress, relative fraction of tetrahedral($sp^3$) bonds, and surface roughness have also been characterized as a function of substrate bias voltages and partial gas($N_2$) pressures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.12
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• pp.814-818
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• 2016

DSSCs (dye-sensitized solar cells) based on $TiO_2/SiO_2$ multi layer AR (anti-reflection) coating on the outer glass FTO (fluorine-doped tin oxide) substrate are investigated. We have coated an AR layer on the surface of a DSSCs device by using an IAD (ion beam-assisted deposition) system and investigated the effects of the AR layer by measuring photovoltaic performance. Compared to the pure FTO substrate, the multi layer AR coating increased the total transmittance from 67.4 to 72.9% at 530 nm of wavelength. The main enhancement of solar conversion efficiency is attributed to the reduction of light reflection at the FTO substrate surface. This leads to the increase of Jsc and the efficiency improvement of DSSCs.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1542-1545
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• 2009

For the application of flexible substrate to future display and new transparent devices, indium tin oxide (ITO) thin film was formed on polycarbonate(PC) substrate at room temperature by in-line sputter system. During the ITO sputtering, Ar and $O_2$ reaction gas were fixed at a constant value and the process pressure was varied from 3 to 7 mtorr. From the electrical and the optical properties of sputtered ITO films, the sheet resistances of as-deposited ITO films varied with a different pressure and the optical transmittances of the ITO films at visible wavelength were maintained above 85%. The results are considered to be due to the saturation of $O_2$ atoms from reaction in ITO film.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.2
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• pp.34-40
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• 2013

Various depositional conditions, such as substrate, pressure, deposition time, temperature of substrate, power and gas composition, have mainly been studied to attain DLC films using RF sputtering system up to the current. In this study, the $N_2/Ar/CH_4$ gas mixture factored on characteristics of DLC deposited film such as structure, hardness, electrical property were investigated. The concentration of the $N_2$ gas in the sputtering gas may be a significant effect on the growth rate of the doped films, because nitrogen ions react not only with the carbon atoms on the target but also with $C_xH_y$ ions in the plasma on the substrate surface. It was seen from this experimental that the resistance of deposited film is decreased, and the relative intensity ratio of D to G peak is increased as nitrogen content of film deposition is increased.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.7
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• pp.288-292
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• 2003

AlM thin film has been deposited on A1$_2$O$_3$ substrate by reactive radio frequency(RF) magnetron sputtering method under various operating conditions such as working pressure, fraction of nitrogen partial pressure, and substrate temperature. Scanning Electron Microscope(SEM), X-ray Diffraction(XRD), and Atomic Force Microscope(AFM) have been measured to find out structural properties and preferred orientation of AlN thin films. SAW velocity of IDTs/AlN/Si structure was about 5038［㎧］ at the center frequency of 251.9［MHz］ and insertion loss was measured to be relatively low value of 35.6［dB］. SAW velocity of IDTs/AlN/A1$_2$O$_3$ structure was improved to be about 5960［㎧］ at the center frequency of 296.7［MHz］.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1976-1981
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• 2009

Transparent conducting aluminum-doped zinc oxide (AZO) thin films were deposited on Coming glass substrate using an Gun-type rf magnetron sputtering deposition technology. The AZO thin films were fabricated with an AZO ceramic target (Zn: 98wt.%, $Al_2O_3$: 2wt.%). The AZO thin films were deposited with various growth conditions such as the substrate temperature, oxygen pressure. X -ray diffraction (XRD), UV/visible spectroscope, atomic force microscope (AFM), and Hall effect measurement system were done in order to investigate the properties of the AZO thin films Among the AZO thin films prepared in this study, the one formed at conditions of the substrate temperature $100^{\circ}C$, Ar 50 sccm, $O_2$ 5 sccm and working pressure 5 motor showed the best properties of an electrical resistivity of $1.763{\times}10^{-4}\;[{\Omega}{\cdot}cm]$, a carrier concentration of $1.801{\times}10^{21}\;[cm^{-3}]$, and a carrier mobility of $19.66\;[cm^2/V{\cdot}S]$, which indicates that it could be used as a transparent electrode for thin film transistor and flat panel display applications.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.5
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• pp.243-248
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• 2001

In this paper, we present theoretical and experimental study on the viscous damping of the on-substrate torsional micromirrors, oscillating near the silicon substrates. In this theoretical study, we develop theoretical models and test structures for the viscous damping of the on-substrate torsional micromirrors. From a finite element analysis, we estimate the theoretical damping coefficients of the torsional micromirrors. From a finite element analysis, we estimate the theoretical damping coefficients of the torsional micromirrors, fabricated by the surface-micromaching process. From the electrostatic test of the fabricated devices, frequency-dependent rotationalvelocity of the micromirrors has been measured at the atmospheric pressure using devices, frequency-dependent rotational velocity of the micromirrors has been measured at the atmospheric pressure using the Mach-Zehnder interferometer system. Experimental damping coefficients have been extracted from the least square fit of the measured rotational velocity within the filter bandwidth of 150 kHz. We have compared the theoretical values and the experimental results on the dynamic performance of the micromirrors. The theoretical analysis overstimates the resonant frequency in the amount of 15%, while underestimating the viscous damping in the factors of 10%.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1408-1409
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• 2007

In this paper, we developed a hybrid simulation model of carbon laser ablation under the Ar plasmas consisted of fluid and particle methods. Three kinds of carbon particles, which are carbon atom, ion and electron emitted by laser ablation, are considered in the computation. In the present modeling, we adopt capacitively coupled plasma with ring electrode inserted in the space between the substrate and the target, graphite. This system may take an advantage of ${\mu}m$-sized droplets from the sheath electric field near the substrate. As a result, in Ar plasmas, carbon ion motions were suppressed by a strong electric field and were captured in Ar plasmas. Therefore, a low number density of carbon ions were deposited upon substrate. In addition, the plume motions in Ar gas atmosphere was also discussed.