• 한국진공학회지
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• 제6권S1호
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• pp.70-74
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• 1997

The study of the thickness dependence of the electron energy structure of Fe, Ni, Ti and Zr sublayers in Ni/Ti and Fe/Zr multilayers by using the experimental and computer simulated optical spectroscopy has been performed. A series of Ni/Ti and Fe/Ze multiayered films (MLF) with a bilayer period of 0.5 - 30 nm and constant (Ni/Ti) / different (Fe/Zr) sublayer thickness ratios were prepared by using computer-controlled double-pair target face-to-face sputtering onto a glass substrate at room temperature (RT) Computer simulation of the resulting optical properties of these MLF was carried out by solving of multireflection problem with a matrix method assuming either "sharp" interfaces resulting in rectangular depth profiles of the components or "mixed" (alloy-like) interfaces of variable thickness between pure-metal sublayers. Optical constants of pure bulk metals as well as equiatomic alloy interfaces were employed in these simulations. It was shown that the difference between experimental and simulated optical properties of the investigated MLF increases with decrease in sublayer thickness. This result allows to conclude that the electronic structures of sublayers below 4-5 nm thickness in mlf differ from the corresponding bulk metals.ponding bulk metals.

• Elastomers and Composites
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• 제58권1호
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• pp.1-10
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• 2023

In this study, we investigate the liquid crystal (LC) alignment of LC cells created from plant-based polysaccharide derivatives, such as guar gum. Guar gum films exhibit satisfactorily high optical transparency in the visible light region (400-750 nm). For example, the transmittance of polyimide films, which are the most typically used LC alignment layers, is 87%, whereas that of guar gum films deposited onto a glass substrate at a wavelength of 550 nm is approximately 99%. The observed LC alignment depends on the rubbing depth. For example, an LC cell comprising a guar gum film fabricated via rubbing at rubbing depths of 0.1, 0.2, 0.3, and 0.4 mm exhibits a planar LC alignment, whereas it exhibits a vertical LC alignment at a rubbing depth of 0.5 mm. Additionally, the LC alignment is shown to be correlated with the total surface energy of the guar gum films. When the total surface energy of a rubbed guar gum film exceeds 58.10 mJ/m², an LC cell comprising the guar gum film exhibits a stable and vertical LC alignment. Therefore, guar gum can be used to realize the vertical alignment system of LC via a simple adjustment of the rubbing depth.

• Current Photovoltaic Research
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• 제11권4호
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• pp.103-107
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• 2023

A Nickel oxide (NiO_x) thin films were prepared via sol-gel process on a transparent conductive oxide glass substrate. The NiO_x thin films were spin-coated in ambient air and subsequently annealed for 30 minutes at temperatures ranging from 150℃ to 450℃. The structural and optical characteristics of the NiO_x thin films annealed at various temperatures were measured using X-ray diffraction, field emission scanning electron microscopy, and ultraviolet-visible spectroscopy. After optimizing the NiO_x coating conditions, perovskite solar cells were fabricated with p-i-n inverted structure, and its photovoltaic performance was evaluated. NiO_x thin films annealed at 350℃ exhibited the most favorable characteristics as a hole transport layer, resulting in the highest power conversion efficiency of 17.88 % when fabricating inverted perovskite solar cells using this film.

• 한국전기전자재료학회논문지
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• 제37권3호
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• pp.309-313
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• 2024

The key to determining the lifetime of OLED device is how much brightness can be maintained. It can be said that there are internal and external causes for the degradation of OLED devices. The most important cause of internal degradation is bonding and degradation in the excited state due to the electrochemical instability of organic materials. The structure of OLED modeled in this paper consists of a cathode layer, electron injection layer (EIL), electron transport layer (ETL), light emission layer, hole transport layer (HTL), hole injection layer (HIL), and anode layer on a glass substrate from top to bottom. It was confirmed that the temperature generated in OLED was distributed around the maximum of 343.15 K centered on the emission layer. It can be seen that the heat distribution generated in the presented OLED structure has an asymmetrically high temperature distribution toward the cathode, which is believed to be because the sizes of the cathode and positive electrode are asymmetric. Therefore, when designing OLED, it is believed that designing the structures of the cathode and anode electrodes as symmetrically as possible can ensure uniform heat distribution, maintain uniform luminance of OLED, and extend the lifetime. The thermal distribution of OLED was analyzed using the finite element method according to Comsol 5.2.

• 한국전기전자재료학회논문지
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• 제37권2호
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• pp.169-174
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• 2024

In this study, the structural, electrical, and optical properties of AZO films of various thicknesses are compared. The AZO films were deposited on a glass substrate by FTS (Facing-Target-Sputtering) This research was conducted to find the optimal thickness for Transparent Conductive Oxide (TCO). AZO has suitable properties for TCO such as low resistivity, and high transmittance. Thin films of all thicknesses showed a transmittance of over 80% in the visible light region and electrical properties improved as thickness increased. It was confirmed that the film of 300 nm thick had the best performance due to its low resistivity, and uniform surface. This research is expected to help find optimal conditions in various fields where TCO is used, such as solar cells, displays, and sensors in the future.

• 한국정보통신학회논문지
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• 제14권3호
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• pp.691-698
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• 2010

본 연구에서는 RF magnetron sputtering 법으로 AZO 세라믹 타켓 ($Al_2O_3$ : 3 wt%)을 이용하여 Eagle 2000 유리 기판위에 기판온도 ($100{\sim}500^{\circ}C$)와 공정압력 (10 ~ 40 mTorr)에 따른 AZO 박막을 제작하여, 결정화 특성과 전기적 및 광학적 특성을 조사하였다. 모든 AZO 박막은 육방정계구조를 가지는 다결정 이었고, (002)우선 배향성이 관찰되었다. 기판온도 $300^{\circ}C$, 10 mTorr에서 제작한 AZO 막에서 가장 우수한 (002) 배향성을 나타냈으며, 이때의 반가폭 값은 $0.42^{\circ}$였다. 전기적 특성은 기판온도 $300^{\circ}C$, 10 mTorr에서 가장 낮은 비저항 $2.64{\times}10^{-3}\;{\Omega}cm$과 우수한 캐리어 농도 및 이동도를 $5.29{\times}10^{20}\;cm^{-3}$, $6.23\;cm^2/Vs$를 나타내었다. 모든 AZO 박막은 가시광 영역에서 80%의 투과율을 나타내었으며, 기판온도 증가와 공정압력 감소에 따른 Al 도핑효과의 증가로 밴드 갭이 넓어지는 Burstein-Moss 효과가 관찰 되었다.

• 센서학회지
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• 제9권2호
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• pp.146-152
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• 2000

고주파 마그네트론 스퍼터링법으로 Li이 도핑된 ZnO(ZnO:Li) 박막을 코닝 7059 글라스 기판상에 증착하였다. 도핑량은 스퍼터링용 ZnO타겟내의 $Li_2CO_3$의 첨가량을 달리하여 조절하였다. 타겟내의 $Li_2CO_3$의 첨가량에 따른 구조적 특성을 XRD, AFM 및 SEM으로 조사하였으며 기판온도, 고주파출력 및 $O_2/Ar$ 가스비에 따른 Li이 도핑된 ZnO박막의 전기적 특성을 조사하였다. 타겟내의 $Li_2CO_3$의 첨가량과 증착조건이 막의 구조적 및 전기적 특성에 미치는 영향을 조사하였다. $Li_2CO_3$의 첨가량이 1wt%이하인 타겟으로 기판온도 $200^{\circ}C$, $O_2$/Ar 가스비 100%, 고주파 출력 100W에서 스퍼터된 ZnO:Li 박막이 표면거칠기가 낮은 우수한 표면형상, 강한 c-축 우선배향성 및 $10^8{\Omega}cm$ 이상의 큰 비저항을 보였다.

• 조명전기설비학회논문지
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• 제24권4호
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• pp.110-115
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• 2010

본 논문에서는 rf 마그네트론 스퍼터링 기술을 이용하여 코닝 글라스 기판 위에 갈륨이 도핑된 산화아연(GZO)을 투명 전도막으로 제작하여 그 전기적 및 광학적 특성을 조사하였다. GZO 박막의 제작은 Zn : 97[wt%], $Ga_2O_3$ : 3[wt%]의 GZO 세라믹 타겟을 이용하였으며, 기판온도 및 산소압력과 같은 증착조건을 변화시키며 증착하였다. 본 연구에서 제작된 GZO 박막중 기판온도 200[$^{\circ}C$], Ar 50[sccm], $O_2$ 5[sccm], rf power 80[W] 및 증착압력 5[mtorr]의 조건에서 제작된 박막에서 가시광 영역에서 90[%] 이상의 높은 가시광 투과율, $2.536{\times}10^{-4}[{\Omega}{\cdot}cm]$의 비저항, $7.746{\times}10^{20}[cm^{-3}]$의 캐리어 농도 및 31.77[$cm^2V{\cdot}S$]의 캐리어 이동도로 가장 좋은 전기적 특성이 관찰되었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권3호
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• pp.149-158
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• 2005

This paper describes design, fabrication, and application of the silicon based temperature controllable micro reactor. In order to achieve fast temperature variation and low energy consumption, reaction chamber of the micro reactor was thermally isolated by etching the highly conductive silicon around the reaction chamber. Compared with the model not having thermally isolated structure, the thermally isolated micro reactor showed enhanced thermal performances such as fast temperature variation and low energy consumption. The performance enhancements of the micro reactor due to etched holes were verified by thermal experiment and numerical analysis. Regarding to 42 percents reduction of the thermal mass achieved by the etched holes, approximately 4 times faster thermal variation and 5 times smaller energy consumption were acquired. The total size of the fabricated micro reactor was $37{\times}30{\times}1mm^{3}$. Microchannel and reaction chamber were formed on the silicon substrate. The openings of channel and chamber were covered by the glass substrate. The Pt electrodes for heater and sensor are fabricated on the backside of silicon substrate below the reaction chamber. The dimension of channel cross section was $200{\times}100{\mu}m^{2}$. The volume of reaction chamber was $4{\mu}l$. The temperature of the micro reactor was controlled and measured simultaneously with NI DAQ PCI-MIO-16E-l board and LabVIEW program. Finally, the fabricated micro reactor and the temperature control system were applied to the thermal denaturation and the trypsin digestion of protein. BSA(bovine serum albumin) was chosen for the test sample. It was successfully shown that BSA was successfully denatured at $75^{\circ}C$ for 1 min and digested by trypsin at $37^{\circ}C$ for 10 min.

• 한국재료학회지
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• 제8권10호
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• pp.961-968
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• 1998

상변화형 광디스크의 보호막으로 사용되는 $ZnS-SiO_2$ 유전체막을 RF magnetron 스퍼트링방법에 의하여 제조하는 경우에 기판 바이어스전압의 영향을 조사하기 위하여, 알곤가스 분위기에서 ZnS(80mol%)-$SiO_2$(20mol%)타겟을 사용하여 Si Wafer와 Corning flass 위에 박막을 증착시켰다. 본 실험에서는 여러 실험 변수를 효과적으로 조절하면서 실험의 양을 줄이고 도시의 산포를 동시에 만족시키는 최적조건으로 타겟 RF 출력 200W, 기판 RF 출력 20W, 아르곤 압력 5mTorr과 증착시간 20분을 얻을 수 있었으며, 신뢰구간 95%에서 확인실험을 수행하였다. 증착된 박막의 열적 저항성을 측정하기 위해 $300^{\circ}C$와 $600^{\circ}C$에서 열처리시험을 수행하였고, Spectroscopic Ellipsometry 측정을 통한 광학적 데이터를 바탕으로 Bruggeman EMA(Effective Medium Approximation)방법을 이용하여 기공(void)분률을 측정하였다. 본 연구결과에 의하면 특성치 굴절률에 대하여 기판 바이어스인자와 증착시간 사이에는 서로 교호작용이 강하게 존재함을 확인할 수 있었다. TEM분석과 XRD 분석 결과에 의하면 기판 바이어스를 가한 최적조건에서 증착된 미세조직은 기존의 바이어스를 가하지 않을 조건에서 증착시킨 박막보다 미세한 구조를 가지며, 또한 과도한 바이어스전압은 결정구조의 조대화를 야기시켰다. 그리고 적절한 바이어스전압은 박막의 밀도를 증가시키며, 기공분률을 약 3.7%정도 감소시킴을 확인할 수 있었다.