• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.454-454
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• 2010

In order to achieve a high efficient a-Si solar cell, the TCO (transparent conductive oxide) substrates are required to be a low sheet resistivity, a high transparency, and a textured surface with light trapping effect. Recently, a zinc oxide (ZnO) thin film attracts our attention as new coating material having a good transparent and conductive for TCO of solar cells. In this paper the optical properties of $H_2$ post-treated BZO (boron doped ZnO, ZnO:B) thin film are investigated with $O_2$-plasma treatment. The BZO thin films by MOCVD (Metal Organic Chemical Vapor Deposition) are investigated and the samples of $H_2$ post-treated BZO thin film are tested with $O_2$-plasma treatment by plasma treatment system with 13.56 MHz as RIE (Reactive Ion Etching) type. We measured the optical properties and surface morphology of BZO thin film with and without $O_2$-plasma treatment. The optical properties such as transmittance, reflectance and haze are measured with integrating sphere and ellipsometer. This result of the BZO thin film with and without $O_2$-plasma treatment is application to the TCO for solar cells.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.91-94
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• 2022

Top emission organic light-emitting diode is commonly used because of high efficiency and good color purity than bottom - emission organic light-emitting device. Unlike BEOLED, TEOLED contain semi-transparent metal cathode. Because of semi-transparent cathode, micro cavity effect occurs in TEOLED. We optimized this effect by changing the thickness of hole injection layer. Device consists of is indium-tin-oxide / N,N'-Di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine (x nm) / tris-(8-hydroxyquinoline) aluminum (50nm) / LiF(0.5nm) / Mg:Ag (1:9), and we changed NPB thickness which is used as HTL in our device in order to study how micro cavity effects are changed by optical path. As the results, NPB thickness at 35nm showed the current efficiency of 8.55Cd/A.

• 방사성폐기물학회지
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• 제21권1호
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• pp.9-22
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• 2023

Spin-off pyroprocessing technology and inert anode materials to replace the conventional carbon-based smelting process for critical materials were introduced. Efforts to select inert anode materials through numerical analysis and selected experimental results were devised for the high-throughput reduction of oxide feedstocks. The electrochemical properties of the inert anode material were evaluated, and stable electrolysis behavior and CaCu generation were observed during molten salt recycling. Thereafter, CuTi was prepared by reacting rutile (TiO₂) with CaCu in a Ti crucible. The formation of CuTi was confirmed when the concentration of CaO in the molten salt was controlled at 7.5mol%. A laboratory-scale electrorefining study was conducted using CuTi(Zr, Hf) alloys as the anodes, with a Ti electrodeposit conforming to the ASTM B299 standard recovered using a pilot-scale electrorefining device.

• Transactions on Electrical and Electronic Materials
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• 제9권1호
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• pp.6-11
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• 2008

In this study, we investigated effects of hydrogen annealing (HA) and plasma nitridation (PN) applied in order to improve $Si/SiO_2$ interface characteristics of TiN metal gate. In result, HA and PN showed a positive effect decreasing number of interface state $(N_{it})$ respectively. After FN stress for verifying reliability, however, we identified rapid increase of $N_{it}$ for TiN gate with HA, which is attributed to hydrogen related to a change of $Si/SiO_2$ interface characteristic. In contrast to HA, PN showed an improved Nit and gate oxide leakage characteristic due to several possible effects, such as blocking of Chlorine (Cl) diffusion and prevention of thermal reaction between TiN and $SiO_2$.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.622-628
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• 2013

Nanocrystalline spinel lithium manganese oxide ($LiMn_2O_4$) powders with narrow-size-distribution, pure-phase particles, and high crystallinity with an average crystallite size of about 70 nm were synthesized at $600^{\circ}C$ for 6 h in air by freeze drying method. Spinel $LiMn_2O_4$ is also prepared by sol-gel using citric acid as a chelating agent. The influence of different parameters such as pH conditions, solvent, molar ratio of citric acid to total metal ions, calcination temperature, starting material on the structure, morphology and purity of this oxide was investigated. The results of sol-gel method show that pure $LiMn_2O_4$ with average crystallite size of about 130 nm can be produced from nitrate salts as starting materials at $800^{\circ}C$ for 6 h in air. The optimum pH and molar ratio of chelating agent to total metal ions are $4{\leq}pH{\leq}6$ and 1.0, respectively. A possible mechanism on the formation of the nanocrystallines synthesized by sol-gel was also discussed. At the end a comparison of the differences between two methods was made on the basis of x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) tests.

• Transactions on Electrical and Electronic Materials
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• 제12권6호
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• pp.262-266
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• 2011

A simulation study of a current-mode direct current (DC)-DC boost converter is presented in this paper. This converter, with a fully-integrated power module, is implemented by using bipolar complementary metal-oxide semiconductor (BiCMOS) technology. The current-sensing circuit has an op-amp to achieve high accuracy. With the sense metal-oxide semiconductor field-effect transistor (MOSFET) in the current sensor, the sensed inductor current with the internal ramp signal can be used for feedback control. In addition, BiCMOS technology is applied to the converter, for accurate current sensing and low power consumption. The DC-DC converter is designed with a standard 0.35 ${\mu}m$ BiCMOS process. The off-chip inductor-capacitor (LC) filter is operated with an inductance of 1 mH and a capacitance of 12.5 nF. Simulation results show the high performance of the current-sensing circuit and the validity of the BiCMOS converter. The output voltage is found to be 4.1 V with a ripple ratio of 1.5% at the duty ratio of 0.3. The sensing current is measured to be within 1 mA and follows to fit the order of the aspect ratio, between sensing and power FET.

• 대한방사선기술학회지:방사선기술과학
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• 제40권4호
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• pp.621-626
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• 2017

본 논문에서는 방사선치료 시 용적 선량 평가에 응용할 수 있는 광 도시메트리 시스템을 구축하고 100 MeV 고선속 양성자 빔에 대한 특성 평가를 수행하였다. 광 도시메트리 시스템은 액체 유기 섬광체와 카메라 렌즈, 고감도 저잡음 화상(complementary metal-oxide-semiconductor; CMOS) 카메라로 구성되며, 2 m 거리에 영상의 화각(field of view; FOV)이 15 cm가 되도록 설계 및 제작하였다. 구축된 광 도시메트리 시스템은 100 MeV 양성자 빔에 대하여 1~40 Gy 선량 범위에서 선량-출력의 직선성을 확인하였으며, 심부선량백분율 데이터와 등선량 곡선을 획득하였다. 본 연구에서는 용매의 인체조직등가성에 제한점이 있지만 광 도시메트리 절차를 확립하였으며, 새로운 용적 선량 평가법의 제안으로 그 의미가 있다.

• 한국세라믹학회지
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• 제55권3호
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• pp.203-223
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• 2018

The development of two-dimensional graphene layers has recently attracted considerable attention because of its tremendous application in various research fields. Semi-metal materials have received significant attention because of their excellent biocompatibility as well as distinct physical, chemical, and mechanical properties. Taking into account the technical importance of graphene in various fields, such as complementary metal-oxide-semiconductor technology, energy-harvesting and -storage devices, biotechnology, electronics, light-emitting diodes, and wearable and flexible applications, it is considered to be a multifunctional component. In this regard, material scientists and researchers have primarily focused on two typical problems: i) direct growth and ii) low-temperature growth of graphene. In this review, we have considered only cold growth of graphene. The review is divided into five sections. Sections 1 and 2 explain the typical characteristics of graphene with a short history and the growth methods adopted, respectively. Graphene's direct growth at low temperatures on a required substrate with a well-established application is then precisely discussed in Sections 3 and 4. Finally, a summary of the review along with future challenges is described in Section 5.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.215-225
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• 2002

In order to enhance the thermal stability of binder materials of bonded type solid lubricants, several combinations of metal-alkoxide based sol-gel materials such as methyltrimethoxysilane(MTMOS), $titaniumisopropoxide(Ti(Opr^{j})_{4})$, $zirconiumisopropoxide(Zr(Opr^{j})_{4})$ and $aluminumbutoxide(Al(Obu^{t})_{4})$ were chemically modified by epoxy-, acrylic- and fluoro-silane compounds, respectively, in this work. Friction and wear characteristics of these hybrid ceramic materials were tested with a micro tribe-tester where a reciprocating steel ball slid on a test material, and the tribological property was also evaluated with respect to both heat-curing temperature and tile time. Test results generally showed that hybrid ceramic materials modified by epoxy-silane compounds had a low friction compared to others. And the higher heat-curing temperature and the longer heat treatment time resulted in the higher friction and the lower wear. IR spectroscopic analyses revealed that it was caused mainly by the increased metal oxide content in hybrid ceramics when the heat-curing temperature was over $320^{\circ}C$.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1572-1575
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• 2005

Poly(vinyl phenol)(PVP)/$TiO_2$ nanocomposite the films have been prepared incorporating metal alkoxide with vinyl polymer to obtain high dielectric constant gate insulating material for a organic thin film transistor. The surface composition, the morphology, and the thermal and electrical properties of the hybrid nanocomposite films were observed by ESCA, scanning electron microscopy (SEM), atomic force microscopy(AFM), and thermogravimetric analysis (TGA). Thin hybrid films exhibit much higher dielectric constants (7.79 at 40wt% metal alkoxide).