• Title, Summary, Keyword: ZnO

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Optical Properties of All Solution processed ZnO/Ag/ZnO Multilayers (용액공정으로 제작한 ZnO/Ag/ZnO 다층구조의 광학적 특성 연구)

  • Lee, Hyungin;Kim, Jiwan
    • Journal of the Microelectronics and Packaging Society
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    • v.25 no.4
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    • pp.119-122
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    • 2018
  • Various ZnO/Ag/ZnO multilayers were fabricated and their optical properties were investigated. Top and bottom ZnO layers were formed by sol-gel method and mid-metal layers were deposited by spin coating. To find suitable deposition condition of Ag, we measure thickness and sheet resistance of Ag monolayer. After the optimization of Ag monolayer, we fabricate ZnO/Ag/ZnO multilayers. Transmittance of ZnO/Ag/ZnO multilayers increased to 63%. In near IR region, transmittance of ZnO/Ag/ZnO multilayers decreased to 35% when the concentration of Ag solution was 2.5wt%.

Analysis of Thermal and Electrical Characteristics of ZnO Arrester Blocks (ZnO 피뢰기 소자의 열적.전기적 특성 분석)

  • Lee, Su-Bong;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.10
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    • pp.82-88
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    • 2007
  • This paper presents the thermal and electrical characteristics of ZnO arrester blocks under the AC voltages. The leakage currents of ZnO arrester blocks were measured as a function of the time. The temperature distributions of ZnO arrester blocks were observed by the thermal image infrared camera. The degradation and thermal runaway of ZnO arrester blocks were closely related to the temperature limit of ZnO arrester blocks which being decided heat generation and dissipation. The temperature and leakage current of ZnO arrester blocks were sensitively changed in a resistance of ZnO arrester blocks. As a result, the degradation and thermal runaway of ZnO arrester blocks depend on the temperature and leakage current of ZnO arrester blocks.

Electrical and optical properties of Al and F doped ZnO transparent conducting film by sol-gel method (Sol-gel법에 의한 Al과 F가 첨가된 ZnO 투명전도막의 전기 및 광학적 특성)

  • Lee, Seung-Yup;Lee, Min-Jae;Park, Byung-Ok
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.16 no.2
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    • pp.59-65
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    • 2006
  • Al-doped and F-doped ZnO (ZnO : Al & ZnO : F) thin films were coated onto glass substrate by sol-gel method. These films showed c-axis orientation in common, but different I(002)/[I(002) + I(101)] and FWHM (full width at half-maximum). In particular, the grain size of the ZnO : Al films decreased with the increase in the Al-doping concentration, while for the ZnO : F films the grain siae increased up to F 3 at% and then decreased. For the electrical properties, Hall effect measurement was used. The resistivity of the ZnO : Al films and the ZnO : F films were, respectively, $2.9{\times}10^{-2}{\Omega}cm$ at Al 1 at% and $3.3{\times}10^{-1}{\Omega}cm$ at F 3 at%. Moreover compared with ZnO:Al films, ZnO:F films have lower carrier concentration (ZnO : Al $4.8{\times}10^{18}cm^{-3}$, ZnO : F $3.9{\times}10^{16}cm^{-3}$) and higher mobility (ZnO : Al $45cm^2/Vs$, ZnO : F $495cm^2/Vs$). For average optical transmittances, ZnO : Al thin films have $86{\sim}90%$ and ZnO : F films have $77{\sim}85%$ comparatively low.

Low Temperature Optical Properties of NiO coated ZnO Nanorods (NiO 코팅 두께에 따른 ZnO 나노막대의 저온분광특성)

  • Shin, Y.H.;Park, Y.H.;Kim, Yong-Min
    • Journal of the Korean Vacuum Society
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    • v.16 no.4
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    • pp.286-290
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    • 2007
  • We fabricated NiO coated ZnO nanorods using ZnO nanorods grown on a Si substrate. After thermal hydrogenation process of these NiO-ZnO core-shell nanorods, we confirm that Ni nanodots were built up on the surface of ZnO nanorods. Photoluminescence (PL) measurements at T=5 K were made to understand the optical properties of these various nanorods. As samples sequencially transformed into $ZnO{\rightarrow}NiO-ZnO{\rightarrow}Ni$ nanodot-ZnO, PL transition energies and intensities are varied as well. In comparison to pure ZnO nanorod, the acceptor bound exciton ($A^0X$) became the minor peak for NiO-ZnO nanorods. On the other hand, for Ni nanodot-ZnO sample, ($A^0X$) transition peak intensity became the most dominant peak. This is due to the fact that during thermal hydrogenation process, appreciable amounts of Ni and hydrogen ions defused into ZnO nanorod which played as accepters.

Growth of ZnO thin films by MOCVD using the buffer layers grown at high temperature (고온 버퍼층을 이용한 ZnO 박막의 MOCVD 성장)

  • Kim, Dong-Chan;Kong, Bo-Hyun;Cho, Hyung-Koun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.108-109
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    • 2006
  • ZnO semiconductor has a wide band gap of 3.37 eV and a large exciton binding energy of 60 meV, and displays excellent sensing and optical properties. In particular, ZnO based 1D nanowires and nanorods have received intensive attention because of their potential applications in various fields. We grew ZnO buffer layers prior to the growth of ZnO nanorods for the fabrication of the vertically well-aligned ZnO nanorods without any catalysts. The ZnO nanorods were grown on Si (111) substrates by vertical MOCVD. The ZnO buffer layers were grown with various thicknesses at $400^{\circ}C$ and their effect on the formation of ZnO nanorods at $300^{\circ}C$ was evaluated by FESEM, XRD, and PL. The synthesized ZnO nanorods on the ZnO film show a high quality, a large-scale uniformity, and a vertical alignment along the [0001]ZnO compared to those on the Si substrates showing the randomly inclined ZnO nanorods. For sample using ZnO buffer layer, 1D ZnO nanorods with diameters of 150-200 nm were successively fabricated at very low growth temperature, while for sample without ZnO buffer the ZnO films with rough surface were grown.

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Preparation of ZnO Nanoparticles by Laser Ablation of Dispersed ZnO Powder in Solution (수용액에 분산된 ZnO 분말의 laser ablation에 의한 ZnO 나노입자의 생성)

  • Gang, Wi-Gyeong;Jeong, Yeong-Geun
    • Journal of the Korean Chemical Society
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    • v.50 no.6
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    • pp.440-446
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    • 2006
  • ZnO nanoparticles were prepared by laser ablation of the ZnO powder dispersed in deionized water and surfactant solutions, and characterized using UV-VIS absorption spectroscopy, X-ray diffractometer and Transmission electron microscopy(TEM). ZnO nanoparticles produced show the pure ZnO crystal state without mixed state with Zn(OH)2 or Zn, and have the band gap energy of 3.35 eV, which is comparable to that of bulk ZnO. While ZnO nanoparticles prepared in SDS solution have the average diameter of 28nm with near spherical shape, those prepared in CTAB solution have the average size of 40 nm with mainly rod-like shape. ZnO colloidal solution of CTAB is more stable than that of SDS. These difference according to surfactants can be explained by difference of electrostatic interaction between surface charge of ZnO and surfactant molecules and by solvation effect in solution.

An Interface Reactions between Sintered Mn-Zn Ferrite and $SiO_2$-PbO-ZnO Bonding Glass (Mn-Zn 페라이트 소결체와 $SiO_2$-PbO-ZnO 삼성분계 봉착유리와의 계면반응)

  • 이대희;박명식;김정주;이병교;조상희
    • Journal of the Korean Ceramic Society
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    • v.37 no.12
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    • pp.1204-1211
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    • 2000
  • Mn-Zn 페라이트 소결체와 SiO$_2$-PbO-ZnO 삼성분계 유리와의 계면반응에서 페라이트와 유리에 각각 첨가된 ZnO가 계면반응에 미치는 영향을 조사하였다. SiO$_2$-PbO-ZnO 삼성분계 유리에 첨가된 ZnO 함량이 낮은 경우 페라이트와의 접합계면에서 생성되는 중간상은 Pb$_2$(Mn,Fe)$_2$Si$_2$O$_{9}$와 Pb$_{8}$(Mn,Fe)Si$_{6}$O$_{21}$의 고용체였으며, ZnO 농도가 증가함에 따라 중간상은 사라졌다. 유리속의 ZnO 성분이 증가함에 따라 페라이트 소결체 쪽의 계면부근에 Zn의 농도가 증가하는 특이한 분포가 나타났다. 이는 유리 속에 첨가된 Zn 이온의 높은 활동도로 인해 페라이트에 포함된 Zn 이온의 용해반응이 선택적으로 억제되어 나타난 것으로 생각된다. 페라이트에 첨가된 ZnO 함량이 낮은 경우 SiO$_2$-PbO 이성분계 유리와의 접합계면에서 페라이트의 용해에 따른 침식과 입계를 통한 유리의 침투가 심하게 일어났으며, ZnO 함량이 증가함에 따라 계면을 통한 상호확산과 반응이 억제되었다.

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Effect of TiO Addition on Morphologies and Luminescence Properties of ZnO Crystals Fabricated by Vapor Transport Method (기상이동법에 의해 제조된 ZnO 결정의 형상 및 발광 특성에 미치는 TiO 첨가의 영향)

  • Lee, Geun-Hyoung
    • Korean Journal of Materials Research
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    • v.28 no.10
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    • pp.590-594
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    • 2018
  • ZnO micro/nanocrystals are formed by a vapor transport method. Mixtures of ZnO and TiO powders are used as the source materials. The TiO powder acts as a reducing agent to reduce the ZnO to Zn and plays an important role in the formation of ZnO micro/nanocrystals. The vapor transport process is carried out in air at atmospheric pressure. When the weight ratios of TiO to ZnO in the source material are lower than 1:2, no ZnO micro/nanocrystals are formed. However, when the ratios of TiO to ZnO in the source material are greater than 1:1, the ZnO crystals with one-dimensional wire morphology are formed. In the room temperature cathodoluminescence spectra of all the products, a strong ultraviolet emission centered at 380 nm is observed. As the ratio of TiO to ZnO in the source material increases from 1:2 to 1:1, the intensity ratio of ultraviolet to visible emission increases, suggesting that the crystallinity of the ZnO crystals is improved. Only the ultraviolet emission is observed for the ZnO crystals prepared using the source material with a TiO/ZnO ratio of 2:1.

Electrical Properties of Zinc Oxide Varistor with $\alpha-Zn_7Sb_2O_{12}$ ($\alpha-Zn_7Sb_2O_{12}$ 첨가에 의한 Zinc Oxide 바리스터의 전기적 특성)

  • 김경남;한상목
    • Journal of the Korean Ceramic Society
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    • v.31 no.11
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    • pp.1396-1400
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    • 1994
  • Electrical properties in the ZnO-Bi2O3-CoO-Zn7Sb2O12 system were investigated with Zn7Sb2O12 content (0.1~2 mol%). The increase of the Zn7Sb2O12 content inhibited the grain growth of ZnO, which showed a narrow grain size distribution of ZnO. The breakdown voltage (Vb) increased markedly with 1 mol% Zn7Sb2O12 addition due to the grain growth control behaviour of the Zn7Sb2O12 . The nonlinear I-V characteristic was significantly influenced by the Zn7Sb2O12 content (or Bi2O3/Zn7Sb2O12 ratio). Addition of 0.5 mol% Zn7Sb2O12 showed the highest nonlinear coefficient ($\alpha$) of 43. The leakage current in prebreakdown region was decreased with increasing Zn7Sb2O12 content.

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A Study on SAW Properties of Bilayer Thin Film Structure Composed of ZnO and Dielectric Thin Films (ZnO 박막과 유전체 박막으로 구성된 이중구조의 물성 및 표면 탄성파 특성)

  • 이용의;김형준
    • Korean Journal of Crystallography
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    • v.6 no.2
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    • pp.134-140
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    • 1995
  • SAW properties of SiNx/ZnO bilayer thin film structure were analyzed. ZnO thin films were deposited by rf magnetron sputter using O2 gas as an oxidizer. Structure of ZnO thin films was affected by Ar/O2 ratio. At the gas ratio of Ar/O2=67/33, the standard deviation of X-ray rocking curve of (002) preferred ZnO thin film was 2.17 degree. This value is sufficient to use ZnO thin films as an acoustic element. SAW velocity of glass/SiNx(7000Å)/Al/ZnO(5μm) structure was max. 2.2% faster than that of ZnO/glass.

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