• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.186-186
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• 2010

액정디스플레이, 유기발광소자 및 태양전지에서 전도성 투명전극으로 indium-tin-oxide (ITO)가 일반적으로 많이 사용되고 있지만 인듐의 희소성과 유독성으로 인하여 ITO를 대체할 수 있는 물질에 대한 많은 연구가 현재 진행되고 있다. ITO 전극을 대체할 수 있는 물질 중에서 Al 도핑된 ZnO (AZO) 박막은 높은 전도성과 광학적 투과성 때문에 다양한 광전소자의 전극과 윈도우 물질로 많은 응용 가능성을 보여주고 있다. 본 연구에서는 여러 가지 스퍼터링 증착 조건에서 증착된 AZO 박막의 전기적특성과 광학적 특성을 조사하였다. 기준시료의 AZO 박막 증착 조건은 ZnO-2 wt.% $Al_2O_3$세라믹 타겟을 사용하였고 $250^{\circ}C$의 기판 온도에서 100 W 전력으로 5 mTorr의 진공 분위기에서 증착되었다. 최적의 AZO 박막 조건을 얻기 위해 증착 온도와 증착 챔버의 압력을 변화하면서 AZO 박막의 전기적 특성 변화와 광학적 특성 변화를 조사하였다. 4-포인트 프로브 측정과 홀 효과측정으로 각기 다른 조건에서 증착한 AZO 박막의 비저항과 전하농도 값을 비교 분석하였고 UV 스펙트로미터 측정을 통해서 AZO 박막의 투과율을 조사하였다. 스퍼터링 방법으로 증착된 AZO 박막은 높은 전도성과 광학적 투과성을 가지기 때문에 액정디스플레이, 유기발광소자 및 태양전지의 투명전극으로 사용할 수 있음을 알 수 있었다.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.4
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• pp.47-52
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• 2017

Recently, a great attention has been paid to the mechanical behavior of ITO (Indium Tin Oxide) film, which is widely used in current smart devices due to its excellent electrical properties and transparency. In this study, the reliability of ITO thin films on flexible substrates was investigated using bending test and bending fatigue test. According to the relative position of ITO and substrate, the experiment was conducted on both outer and inner bending conditions. Inner bending condition exhibited superior electrical stability compared to outer bending test. The electrical resistance during outer bending fatigue test significantly increased compared to that in the inner bending fatigue. The crack nucleation and propagation differs according to the stress state and they have a great influence on the electrical resistance. The crack morphologies were observed by scanning electron microscopy.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.152-158
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• 1995

Eteching characteristics of the Indium Tin Oxide (ITO), which is transparent conductor, was investigated with CH4/H2 and Ar as etching gases for the Reactive Ion Etching (RIE). With CH4/H2 for the etching gas, the highly selective etching characteristics for the ITO on GaAs was obtained. It was examined that the dominant etching parameter for the selective etchning of ITO on GaAs structure was the chamber pressure. But, the etching selectivity for ITO on InP was poor eventhough we tried systematic etching. RIE etching conditins using CH4/H2 gas was limited due to the formation of polymer on the substrates. In the case of Ar gas for the reactive gas, the selectivity of ITO on BaTiO3 was above 10. The etch rete of ITO was more sensitive to the etching parameters than that of BaTiO3, which was almost constant with different etching parameters.

• Journal of the Semiconductor & Display Technology
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• v.7 no.4
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• pp.7-11
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• 2008

ITO (Indium Tin Oxide) thin films have been extensively studied for OLED devices because they have high transparent properties in the visible wavelength and a low electrical resistivity. These ITO films are deposited by rf-magnetron sputtering under different ambient gases (Ar, Ar+$O_2$ and Ar+$H_2$) at $300^{\circ}C$. In order to investigate the influences of the oxygen and hydrogen, the flow rate of oxygen and hydrogen in argon has been changed from 0.5sccm to 5sccm and from 0.01sccm to 0.25sccm respectively. The resistivity of ITO film increased with increasing flow rate of $O_2$ under Ar+$O_2$ while it is nearly constant under Ar+$H_2$. And the peak of ITO films obtained (222) and (400) orientations and the average transmittance was over 80% in the visible range. The OLED device fabricated with different ITO substrates made by configuration of ITO/$\alpha$-NPD/Alq3/LiF/Al to elucidate the performance of ITO substrate for OLED device.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.366-366
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• 2012

무기물 나노입자를 포함한 유기 박막인 나노 복합체를 사용하여 제작한 비휘발성 메모리 소자는 공정의 간단함과 낮은 전력구동이 가능하다는 장점 때문에 차세대 비휘발성 메모리 소자로 각광받고 있다. 다양한 나노입자를 포함한 유기 박막을 사용한 비휘발성 메모리 소자에 대한 연구는 많이 진행되었지만, 코어-쉘 나노입자가 poly (methylmethacrylate) (PMMA) 유기 박막에 분산되어 있는 나노 복합체를 활성층으로 사용하여 제작한 비휘발성 유기 메모리 소자의 전기적 특성과 메모리 메커니즘에 대한 연구는 비교적 미미하다. 본 연구에서는 코어-쉘 나노 입자가 PMMA 박막 안에 분산되어 있는 나노복합체를 사용한 비휘발성 메모리 소자를 제작하여 전기적 특성, 정보 유지력 및 메모리 스위칭 동작에 대하여 관찰 하였다. 소자 제작을 위해 hexane 안에 들어 있는 코어-쉘 나노입자를 Chlorobenzene에 용해되어 있는 PMMA에 넣어 초음파 교반기를 사용하여 나노입자를 고르게 분산하였다. 코어-쉘 나노입자가 PMMA에 고르게 분산 된 용액을 전극으로 사용 할 Indium-tin-oxide가 성장된 glass 위에 스핀코팅을 한 후 열처리를 하여 용매를 제거한 후 코어-쉘 입자가 PMMA에 분산되어 있는 박막을 형성하였다. 코어-쉘 입자가 PMMA에 분산된 나노복합체 위에 Al을 상부전극으로 열 증착하여 비휘발성 메모리 소자를 제작하였다. 제작된 소자의 전류-전압 (I-V) 특성을 측정결과는 특정한 두께에서 낮은 전도도 (ON state)와 높은 전도도 (OFF state)가 존재하는 쌍안정성 특성을 확인하였다. 코어-쉘 나노입자가 포함되지 않은 소자에서는 쌍안정성 특성이 보이지 않아 코어-쉘 나노입자가 비휘발성 메모리 소자의 기억 특성을 나타내는 중요한 저장 매체가 됨을 알 수 있었다. 제작된 메모리 소자의 메모리 동작에 대한 메커니즘 설명은 I-V와 에너지 밴드 구조를 사용하여 설명할 것이다.

• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.71-79
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• 1996

The mechanism of electrochemical polymerization of polypyrrole was analyzed using Q.C.A. via measuring the resonant frequency and resonant resistance of AT-cut quartz crystal, whose electrodes were fabricated with indium tin oxide by sputtering method. The quantity of polymerized polypyrrole was able to be calculated from the resonant frequency and the viscoelasticity of polypyrrole film from resonant resistance. We found that the elastic film is formed at the first stage of the polymerization, but transformed to viscoelastic film later and that this transition repeated at some point. From these results, it was confirmed that the rheological characteristics of electrochemically polymerized polypyrrole thin film can be analyzed using Q.C.A.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.2
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• pp.19-26
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• 2020

Flexible displays have been evolved into curved, foldable, and rollable as the degree of bending increases. Due to the presence of brittle electrodes (e.g. indium-tin oxide (ITO)) that easily cracked and delaminated under severe bending deformation, lowering mechanical stress of the electrodes has been critical issue. Because of this, mechanical stress of brittle electrode in flexible displays has been analyzed mostly in terms of bending radius. On the other hand, in order to make rollable display, various mechanical components such as roller and spring are needed to roll-up or extend the screen for the rollable display apparatus. By these mechanical components, brittle electrode in the rollable display is subjected to the excessive tensile stress due to the retracting force as well as the bending stress by the roller. In this study, mechanical deformation of rollable OLED display was modeled considering boundary conditions of the apparatus. An analytical modeling based on the classical beam theory was introduced in order to investigate the mechanical behavior of the rollable display. In addition, finite element analysis (FEA) was used to analyze the effect of mechanical components in the apparatus on the brittle electrode. Furthermore, a strategy for improving the mechanical reliability of the rollable display was suggested through controlling the stiffness of adhesives in the display panel.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.114.2-114.2
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• 2017

Transparent film heaters (TFHs) based on Joule heating are currently an active research area. However, TFHs based on an indium tin oxide (ITO) monolayer have a number of problems. For example, heating is concentrated in part of the device. Also, heating efficiency is low because it has high sheet resistance ($R_S$). Resistance of indium zinc oxide (IZO) is similar to ITO and it can be used to flexible applications due to its amorphous structure. To solve these problems, our study introduced hybrid layers of IZO/Ag/IZO deposited by magnetron sputtering, and the electrical, optical, and thermal properties were estimated for various thickness of the metal interlayer. It was found that the sheet resistance of the multilayer was mainly dependent on the thickness of the Ag layers. The $R_S$ of IZO(40)/Ag/IZO(40nm) multilayer was 5.33, 3.29, $2.15{\Omega}/{\Box}$ for Ag thickness of 10, 15, and 20nm, respectively, while the $R_S$ of an IZO monolayer(95nm) was $59.58{\Omega}/{\Box}$. The optical transmittance at 550nm for the IZO(95nm) monolayer is 81.6%, and for the IZO(40)/Ag/IZO(40nm) multilayers with Ag thickness 10, 15 and 20nm, is for 72.8, 78.6, and 63.9%, respectively. The defrost test showed that the film with the lowest RS had the highest heat generation rate (HGR) for the same applied voltage. The results indicated that IZO(40)/Ag(15)/IZO(40nm) multilayer has the best suitable property, which is a promising thin film heater for the application in vehicle windshield.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.spc
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• pp.23-29
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• 2022

To detect harmful chemical substances in seawater, we fabricated a prototype sensor and evaluated its performance. The prototype sensor consisted of a detector, housing, and driving circuit. We built the detector by printing an Indium-Tin-Oxide (ITO) nanoparticle film on a flexible substrate, and it had two detection parts for simultaneous detection of temperature and HNS concentration. The housing connected the detector and the driving circuit and was made of Teflon material to prevent chemical reactions that may affect sensor performance. The driving circuit supplied electric power, and display measured data using a bridge circuit and an Arduino board. We evaluated the sensor performances such as response (ΔR), the limit of detection (LOD), response time, and errors to confirm the specification.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.288-289
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• 2011

Indium Tin Oxide (ITO) is a typical highly Transparent Conductive Oxide (TCO) currently used as a transparent electrode material. Most widely used deposition method is the sputtering process for ITO film deposition because it has a high deposition rate, allows accurate control of the film thickness and easy deposition process and high electrical/optical properties. However, to apply high quality ITO thin film in a flexible microelectronic device using a plastic substrate, conventional DC magnetron sputtering (DMS) processed ITO thin film is not suitable because it needs a high temperature thermal annealing process to obtain high optical transmittance and low resistivity, while the generally plastic substrates has low glass transition temperatures. In the room temperature sputtering process, the electrical property degradation of ITO thin film is caused by negative oxygen ions effect. This high energy negative oxygen ions(about over 100eV) can be critical physical bombardment damages against the formation of the ITO thin film, and this damage does not recover in the room temperature process that does not offer thermal annealing. Hence new ITO deposition process that can provide the high electrical/optical properties of the ITO film at room temperature is needed. To solve these limitations we develop the Magnetic Field Shielded Sputtering (MFSS) system. The MFSS is based on DMS and it has the plasma limiter, which compose the permanent magnet array (Fig.1). During the ITO thin film deposition in the MFSS process, the electrons in the plasma are trapped by the magnetic field at the plasma limiters. The plasma limiter, which has a negative potential in the MFSS process, prevents to the damage by negative oxygen ions bombardment, and increases the heat(-) up effect by the Ar ions in the bulk plasma. Fig. 2. shows the electrical properties of the MFSS ITO thin film and DMS ITO thin film at room temperature. With the increase of the sputtering pressure, the resistivity of DMS ITO increases. On the other hand, the resistivity of the MFSS ITO slightly increases and becomes lower than that of the DMS ITO at all sputtering pressures. The lowest resistivity of the DMS ITO is $1.0{\times}10-3{\Omega}{\cdot}cm$ and that of the MFSS ITO is $4.5{\times}10-4{\Omega}{\cdot}cm$. This resistivity difference is caused by the carrier mobility. The carrier mobility of the MFSS ITO is 40 $cm^2/V{\cdot}s$, which is significantly higher than that of the DMS ITO (10 $cm^2/V{\cdot}s$). The low resistivity and high carrier mobility of the MFSS ITO are due to the magnetic field shielded effect. In addition, although not shown in this paper, the roughness of the MFSS ITO thin film is lower than that of the DMS ITO thin film, and TEM, XRD and XPS analysis of the MFSS ITO show the nano-crystalline structure. As a result, the MFSS process can effectively prevent to the high energy negative oxygen ions bombardment and supply activation energies by accelerating Ar ions in the plasma; therefore, high quality ITO can be deposited at room temperature.