• Title/Summary/Keyword: Sol-gel coating

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Fabrication of a (100) Silicon Master Using Anisotropic Wet Etching for Embossing

  • Jung, Yu-Min;Kim, Yeong-Cheol
    • Journal of the Korean Ceramic Society
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    • v.42 no.10 s.281
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    • pp.645-648
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    • 2005
  • To fabricate a (100) silicon hard master, we used anisotropic wet etching for the embossing. The etching chemical for the sili­con wafer was a TMAH 25$\%$ solution. The anisotropic wet etching produces a smooth sidewall surface inclined at 54.7°, and the surface roughness of the fabricated master is about 1 nm. After spin coating an organic-inorganic sol-gel hybrid resin on a silicon substrate, we used the fabricated master to form patterns on the silicon substrate. Thus, we successfully obtained patterns via the hot embossing technique with the (100) silicon hard master. Moreover, by using a single hydrophobic surface treatment of the master, we succeeded in achieving uniform surface roughness of the embossed patterns for more than ten embossments.

Effect of Sr/Zr Ratio and Organic Vehicle Addition on Bond Strength of $SrZrO_3 $ Thin Films ($SrZrO_3 $박막의 접착강도에 미치는 Sr/Zr 몰비와 유기화합물 첨가효과)

  • 이세종;이득용;예경환;송요승
    • Progress in Superconductivity and Cryogenics
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    • v.4 no.1
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    • pp.13-16
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    • 2002
  • $SrZrO_3 $resistive oxide barriers on Ag sheathed Bi2223 tapes were prepared by the sol-gel and dip coating method to reduce AC coupling loss. The performance of the dip-coated $SrZrO_3 $ thin films was evaluated in terms of bond strength by varying the Sr/Zr mol ratio and the amount of organic vehicle (ethyl cellulose and a-terpineol) additives. The bond strength of the coatings increased as the Sr/Zr ratio decreased and the amount of organic vehicle rose, respectively. It was found that the effect of organic vehicle addition was more pronounced, suggesting that the adherence of the $SrZrO_3 $ films on Bi2223 tapes was governed primarily by the amount of organic vehicle additive.

Zinc oxide seed layer 형성 조건 제어를 통한 나노 구조체 형상 조절 연구

  • Lee, Jae-Hyeok;Kim, Seong-Hyeon;Lee, Gyeong-Il;Lee, Cheol-Seung;Jo, Jin-U;Kim, Seon-Min
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.386-386
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    • 2011
  • sol-gel 및 hydrothermal growth method를 이용한 zinc oxide nanorod는 제작 시 고가의 장비가 필요치 않기에 저비용 대면적 박막을 제작하는데 적합하지만 rod들의 array 및 density 조절에서 어려움을 가지고 있다. 본 연구에서는 이러한 nanorod array 형상 조절을 위하여 zinc oxide seed layer 형성 과정 중 precursor solution에 이종 나노 입자를 첨가하였다. 첨가한 seed precursor solution을 spin coating한 이후에 후처리 하여 hydrothermal method를 이용해 성장시켰다. 합성한 rod들을 optic과 FE-SEM으로 측정해 rod들의 density 변화를 확인할 수 있었다.

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Dielectric Properties of $Al_{2}O_{3}-Doped$ BSCT Thick Films ($Al_{2}O_{3}$가 첨가된 BSCT 후막의 유전특성)

  • Lee, Sung-Gap;Kim, Chang-Il;Kim, Jeong-Phil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.11a
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    • pp.338-341
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    • 2002
  • $(Ba_{1-x}Sr_{0.4}Ca_x)TiO_{3}$ (x=0.10, 0.15, 0.20) powders were prepared by the sol-gel method and BSCT thick films were fabricated by the screen-printing method. Their structural and dielectric properties were investigated with variation of composition ratio and $Al_{2}O_{3}$ doping contents. As results of the X-ray diffraction and microstructure analysis, the grain size of BSCT thick films was decreased with increasing $Al_{2}O_{3}$ amount. The thickness of BSCT thick films by 4-coating/drying is about $110{\sim}120{\mu}m$. The tunability increased with decreasing Ca content, and the BSCT(50/40/10) specimen doped with 1.0wt% $Al_{2}O_{3}$ showed the highest value of 12.94% at 5kV /cm.

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Electronic properties of PZT(20/80) thick film and PZT(80/20) thin film multilayer with variation of sintering temperature (다층 PZT(20/80) 후막과 PZT(80/20) 박막의 소결온도에 따른 전기적 특성)

  • Noh, Hyun-Ji;Lee, Sung-Gap;Park, Sang-Man;Bae, Seon-Gi
    • Proceedings of the KIEE Conference
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    • 2006.07b
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    • pp.1243-1244
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    • 2006
  • In this paper, PZT(20/80) thick films were fabricated by the screen-printing method. And the PZT(80/20) coating solution was synthesized by the sol-gel method. PZT(20/80) thick films were screen-printed on the alumina substrates. PZT(80/20) thin film was spin-coated on the PZT(20/80) thick films to obtain densification. And the structural and electrical properties of PZT thick films were investigated with variation of sintering temperature. The PZT specimen sintered at $650^{\circ}C$ showed good relative dielectric constant of 219 and dielectric loss of 2.45%. Also the remanent polarization and the coercive field were $16.48{\mu}C/cm^2$ and 35.48kV/cm, respectively.

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Monodisperse Micrometer-Ranged Poly(methyl methacrylate) Hybrid Particles Coated with a Uniform Silica Layer

  • Han, Seung-Jin;Shin, Kyo-Min;Suh, Kyung-Do;Ryu, Jee-Hyun
    • Macromolecular Research
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    • v.16 no.5
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    • pp.399-403
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    • 2008
  • Monodisperse, micron-sized, hybrid particles having a core-shell structure were prepared by coating the surface of poly(methyl methacrylate)(PMMA) microspheres with silica and by copolymerizing acrylamide (AAm) to supply the hydrogen bonding effect by means of the amide groups. Tetraethoxysilane (TEOS) was then slowly dropped onto the medium under certain conditions. Because of the hydrogen bonding between the amide of the PMMA particles and the hydroxyl group of the hydrolyzed silanol, a silica shell was generated on the PMMA core particles. The morphology of the hybrid particles was investigated with transmission (TEM) and scanning (SEM) electron microscopy as a function of the medium conditions and the amount of TEOS. Improved thermal properties were observed by TGA analysis.

Multi-coated YBa2Cu3O7-x Films Fabricated by a Fluorine-Free Sol-Gel Process

  • Cho, E.A.;Jang, G.E.;Hyun, O.B.
    • Journal of Magnetics
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    • v.16 no.2
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    • pp.186-191
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    • 2011
  • [ $YBa_2C_3O_{7-x}$ ]films were fabricated on a $SrTiO_3$ (100) substrate using a trimethylaceate propionic acid (TMAP)-based MOD process by controlling the precursor solution viscosity, firing temperature, and by using various coatings. The viscosity of the precursor solution was controlled by the addition of Xylenes. The films were heat treated with different temperatures from 750 to $800^{\circ}C$. c-axis oriented films were obtained. After adding 9 ml of Xylene into the precursor solution, the $T_c$ of the YBCO film, which was coated 2 times and heat treated at $800^{\circ}C$, was 86 K and the measured $J_c$ was above 2.5 MA/$cm^2$ at 77 K in a zero-field.

Isothermal Phase Transformation Beahviors in $Al_2O_3$ Coated Y-TZP Powders ($Al_2O_3$로 코팅된 Y-TZP 분말의 등온 상전이 거동)

  • 이종국;양권승
    • Journal of the Korean Ceramic Society
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    • v.30 no.8
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    • pp.651-656
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    • 1993
  • Granulated Y-TZP powders were coated by using Sol-Gel method and the coating effect of Al2O3 on the isothermal phase transformation in Al2O3 coated Y-TZP powders was investigated. During aging, tetragonal phase in Y-TZP powder were isothermally transformed to monoclinic, but the tetragonal phase in Al2O3 coated Y-TZP powders was continuously retained in spite of long aging. It can be considered that the improvement of thermal stability of tetragonal phase in Al2O3 coated Y-TZP powders may be due to the increase of constraint effect near tetragonal phase, and the suppression of surface transformation by obstructing the reaction between the surface of Y-TZP and H2O.

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Effects of Al Concentration on Structural and Optical Properties of Al-doped ZnO Thin Films

  • Kim, Min-Su;Yim, Kwang-Gug;Son, Jeong-Sik;Leem, Jae-Young
    • Bulletin of the Korean Chemical Society
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    • v.33 no.4
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    • pp.1235-1241
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    • 2012
  • Aluminium (Al)-doped zinc oxide (AZO) thin films with different Al concentrations were prepared by the solgel spin-coating method. Optical parameters such as the optical band gap, absorption coefficient, refractive index, dispersion parameter, and optical conductivity were studied in order to investigate the effects of the Al concentration on the optical properties of AZO thin films. The dispersion energy, single-oscillator energy, average oscillator wavelength, average oscillator strength, and refractive index at infinite wavelength of the AZO thin films were found to be affected by Al incorporation. The optical conductivity of the AZO thin films also increases with increasing photon energy.

A Study on Characteristics of ZnO/n-Si Low Cost Solar Cells (ZnO/n-Si 저가 박막태양전지의 특성연구)

  • Baik, D.G.;Cho, S.M.
    • Solar Energy
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    • v.19 no.1
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    • pp.29-36
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    • 1999
  • ZnO/n-Si junctions were fabricated by spin coating with ZnO precursor produced by the sol-gel process. In order to increase the electrical conductivity of ZnO films, the films were n-doped with Al impurity and subsequently annealed at about $450^{\circ}C$ under reducing environments. The ohmic contacts between n-Si and AI for a bottom electrode were successfully fabricated by doping the rear surface of Si substrate with phosphorous atoms. The front surface of the substrate was also doped with phosphorous atoms for improving the efficiency of the solar cells. Consequently, conversion efficiencies ranging up to about 5.3% were obtained. These efficiencies were found to decrease slowly with time because of the oxide films formed at the ZnO/Si interface upon oxygen penetration through the porous ZnO. Oxygen barrier layers could be necessary in order to prevent the reduction of conversion efficiencies.

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