• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.231-231
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• 2013

반사방지막 코팅(Anti-reflection coating)은 태양전지(Solar cell), 발광다이오드(LED) 등의 반사율을 낮추어 효율을 증대시키기 위하여 사용되고 있다. 본 실험에서는 유리 기판 위에 실리콘 타겟을 이용한 Reactive magnetron sputtering 장비를 활용하여, 50~100 mTorr의 높은 공정 압력(High pressure)에서 Ar：O2 유량비를 변화시키며 증착하여 SiO2 반사방지막 코팅층을 형성하였다. Ellipsometer를 이용하여 SiO2 박막층의 굴절률(Refractive index)을 측정한 결과, 공정 압력과 Ar：O2 유량비에 따라 SiO2 박막이 다양한 굴절률을 가지는 것을 확인할 수 있었다. 또한, UV-Vis spectrometer를 이용하여, 190~1,100 nm 파장에서의 반사율(Reflectance)과 투과율(Transmittance)을 측정하여 비교, 분석하였다. 나아가 증착된 SiO2 반사방지막을 비정질 실리콘 박막 태양전지에 적용하여 효율 향상 효과를 실험하였다. 이를 활용하여 낮은 굴절률을 갖는 반사방지용 SiO2 코팅층을 형성하여 태양전지의 광 변환 효율을 상승 시킬 수 있고, 발광다이오드의 광 추출 효율을 증가시킬 있을 것으로 여겨진다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.439-440
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• 2008

Indium Zinc Tin Oxide (IZTO) thin films for transparent thin film transistor (TTFT) were deposited on glass substrate at room temperature by facing targets sputtering (FTS). The FTS system was designed to array two targets facing each other and forms the high- density plasma between. Two different kinds of targets were installed on FTS system. One is ITO ($In_2O_3$ 90wt.%, $SnO_2$ 10wt.%), the other is IZO($In_2O_3$ 90wt%, ZnO 10wt%). The conductive and optical properties of IZTO thin film is determined depending on variation of DC power and working pressure. Therefore, IZTO thin films were prepared with different DC power and working pressure. As-deposited IZTO thin films were investigated by a UV/VIS spectrometer, an X-ray diffractometer (XRD), a scanning electron microscopy (SEM), a Hall Effect measurement system. As a result, all IZTO thin films deposited on glass substrate showed over 80% of transmittance in visible range (400~800 nm) at $O_2$ gas flow rate. We could obtain IZTO thin films with the lowest resistivity $5.67\times10^{-4}$ [$\Omega{\cdot}cm$] at $O_2$ gas flow rate 0.4 [sccm).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.393-394
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• 2008

$TiO_2$ is a wide band-gap semiconductor (3.4 eV) and can only absorb about 5% of sun light in the ultraviolet light region, which largely limits its practical applications because of the lower utility of sun light and quantum yield. In order to move the absorption edge of $TiO_2$ films to visible spectrum range, we have made the impurity level within a band-gap of $TiO_2$ thin film by introduction of oxygen vacancy. Oxygen-defected $TiO_2$ thin film have prepared by reactive sputtering with the partial pressure of Ar:$O_2$=10:90~99.33:0.66 ratio. As a result, we could have the impurity level of about 2.75 eV on condition that oxygen partial pressure is below 7%.

• 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.

• 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］.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1230-1233
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• 2004

The ITO thin films were prepared by the FTS(Facing Targets Sputtering) system. The ITO thin films are deposited by changing the input current and working gas pressure. Then, electric characteristics, transmittance and surface roughness of ITO thin films were measured by Hall effect measurement, UV-VIS spectrometer and AFM. As a result, the ITO thin film was fabricated with resistivity 6xl0$^{-4}$ Ωㆍcm, carrier mobility 52.11 $\textrm{cm}^2$/Vㆍsec, carrier concentration 1.72 x $10^{20}$ $cm^{-3}$ transmittance over 85 % of ITO film at working gas pressure 1 mTorr and input current 0.6 A.

• Journal of the Korean Ceramic Society
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• v.53 no.5
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• pp.563-567
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• 2016

The structural properties of $HfO_2$ films could be improved by thermal treatment owing to their crystallization. We deposited $HfO_2$ films on sapphire by radio frequency (RF) magnetron sputtering, whose base vacuum pressure was lower than $4.5{\times}10^{-6}$ Pa, RF power was 100 W, working temperature was $200^{\circ}C$, working pressure was 3 mTorr, and the density of the active gas (Argon) was 20 sccm. After depositing the $HfO_2$ films, the samples were thermally treated by rapid thermal annealing (RTA) in $O_2$ ambient at different temperatures. Subsequently, the measured physical properties (structural, morphological, and optical) indicated that the crystallite size, refractive index at a wavelength of 632 nm, and packing density increased with rising temperatures. In particular, an $HfO_2$ film thermally treated at $800^{\circ}C$ in $O_2$ ambient had the highest refractive index of 2.0237 and packing density of 0.9638. The relation between optical and structural properties was also analyzed.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.435-438
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• 2003

The effects of oxygen partial pressure and vacuum annealing on the electrical properties of sputtered vanadium oxide($VO_x$) thin films were investigated. The thin films were prepared by r.f. magnetron sputtering from $V_2O_5$ target in a gas mixture of argon and oxygen. The oxygen/(oxygen+argon) partial pressure ratio of 0% and 8% is adopted. Electrical properties of films sputter-deposited under different oxygen gas pressures and in situ annealed in vacuum at $400^{\circ}C$ for 1h and 4h are characterized through electrical conductivity measurements. I-V characteristics were distinguished between linear and nonlinear region. In the low field region the conduction is due to Schottky emission, while at high fields it changes to Fowler-Nordheim tunneling type conduction. The conductivity measurements have shown an Arrhenius dependence of the conductivity on the temperature.

• Journal of Surface Science and Engineering
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• v.31 no.3
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• pp.171-176
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• 1998

Transparent conducting ITO (Indium Tin Oxide) thin films were prepared on soda lime glass by reactive dc magnetron sputtering mothod. The maaterial properties were measured by the X-ray diffraction meter (XRD) and atomic force microscopy (AFM) scanning. As a resuIts, the (400) park for $O_2 gas rate 2% grows uniquely as the preferred orientaon. However, the (400) peak exists at $O_2 gas rate 5% as well as the (222) peak appears abruptly as the main orietation. Both <100> and <111> grain alignments are consisted simultaneously in the XRE pattern of ITO thin films. The electrical charcteristics were esimated by the electrical resistivity, optical transmission, and Hall mobillty, ect. The resistivity of ITO thin film deposited at 4cm from the substrate center is increased from $2\times10^-4$ to $8\times10^-4\Omega$cm as a function of $O_2$ gas pressure (0~5%). The optical transmission curves with a rising of $O_2$ gas rate become shifted into longer wavelength range.