• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.224-227
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• 2001

ZnO buffer layers were used to grow ZnO films on c-plane sapphire substrates. The role of ZnO buffer layers in the growth of ZnO thin films on sapphire substrates was investigated by scanning electron microscopy, X-ray diffraction, and Photolumminescence(PL) measurements. At the optimized ZnO buffer layer thickness of 100 $\AA$, FWHM of $\theta$ -rocking curve of ZnO thin films was minimized to 0.73 degrees and room temperature PL spectra showed that deep level emission was not hardly seen. The optimization of the ZnO buffer layer thickness resulted in improvements of the surface morphology and crystalline quality of ZnO thin films.

• 마이크로전자및패키징학회지
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• 제14권3호
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• pp.15-20
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• 2007

플라스틱 기판에 적용이 가능한 최대 공정온도 $270^{\circ}C$ 이하에서 ZnO-TFT 소자를 제작하였다. ZnO-TFT 소자는 bottom gate 구조로 제작되었으며, ICP-CVD로 형성된 $SiO_2$ 산화물 게이트 공정을 제외하고는 모든 박막증착 공정은 RF-magnetron sputtering process를 이용하였다. ZnO 박막은 Ar과 $O_2$ gas 유량의 비율에 따라 여러 가지 조건에서 RF-magnetron sputtering 시스템을 이용하여 상온에서 증착하였다. Ar과 $O_2$ gas의 비율에 따라 제작된 TFT 소자는 모두 enhancement 모드의 소자특성을 나타내었고, 또한 가시광선영역에 있어 80% 이상의 높은 투과율을 보였다. ZnO 증착시 순수 Ar을 사용하여 제작된 ZnO-TFT의 경우에, $1.2\;cm^2/Vs$의 field effect mobility, 8.5 V의 threshold voltage, 그리고 $5{\times}10^5$의 높은 on/off ratio, 1.86 V/decade의 swing voltage로 가장 우수한 전기적 특성을 보였다.

• 청정기술
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• 제22권2호
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• pp.89-95
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• 2016

화장품이나 타이어에 주로 사용되는 ZnO 나노입자에 대한 나노위해성 문제가 대두되고 있다. 이에 본 연구에서는 수계상에 존재하는 ZnO 나노입자에 대한 제거 및 생물학적 독성평가를 실시하였다. 송사리(O. Latipes) 수정란을 이용한 단기 노출평가에서는 5 mg L⁻¹에서는 일부 개체에서 기형이 관찰되었고, 10 mg L⁻¹에서 성장지연에 의한 부화율저감이 관찰되었다. 이러한 결과를 바탕으로 ZnO 나노입자가 수생생물종에게 독성을 보인다는 것을 확인하고, 이를 제거하기 위한 방법인 침전법을 제안하였다. Na₂S와 Na₂HPO₄를 이용하여 ZnO를 ZnS와 Zn₃(PO₄)₂로 전환시켜 침전시켰으며, 이들의 침전에 의한 제거율은 거의 100%에 이르렀다. 또한 해당 침전물 대한 물벼룩(D. magna) 급성독성 평가에서 어떠한 독성 영향도 찾지 못하였다. 이는 ZnO의 황 및 인처리를 통한 변환이 독성 감소에 효과적이었음을 나타낸다.

• 한국세라믹학회지
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• 제33권2호
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• pp.149-154
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• 1996

ZnO and Al-doped ZnO thin films were prepared by sol-gel dip-coating method and electrical and optical properties of films were investigated. Using the zinc acetate dihydrate and acetylaceton(AcAc) as a chelating agent stable ZnO sol was synthesized with HCl catalyst. Adding aluminium chloride to the ZnO sol Al-doped ZnO sol could be also synthesized. As Al contents increase the crystallinity of ZnO thin film was retarded by increased compressive stress in the film resulted from the difference of ionic radius between Zn2+ and Al3+ The thickness of ZnO and Al-doped ZnO thin film was in the range of 2100~2350$\AA$. The resistivity of ZnO thin films was measured by Van der Pauw method. ZnO and Al-doped ZnO thin films with annealing temperature and Al content had the resistivity of 0.78~1.65$\Omega$cm and ZnO and Al-doped ZnO thin film post-annealed at 40$0^{\circ}C$ in vacuum(5$\times$10-5 torr) showed the resistivity of 2.28$\times$10-2$\Omega$cm. And the trans-mittance of ZnO and Al-doped ZnO thin film is in the range of 91-97% in visible range.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.285-285
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• 2010

Zinc oxide (ZnO) is a direct band gap semiconductor with 3.37 eV, which has in a hexagonal wurtzite structure. ZnO is a good candidate for a photocatalyst because it has physical and chemical stability, high oxidative properties, and absorbs of ultraviolet light. During ZnO is irradiated by UV light, redox (reduction and oxidation) reactions will occur on the ZnO surface, generating the radicals O2- and OH. These two powerful oxidizing agents have been proven to be effective in decomposition of harmful organic materials, converting them into CO2 and H2O. Therefore, we assume that oxygen on the surface of ZnO is a very important factor in the photocatalytic activities of ZnO nanoparticles. Recently, ZnO nanoparticles are studied in various application fields by many researchers. Photocatalyst research is progressing much in various application fields. But the ZnO nanoparticles have disadvantage that is unstable in water in comparison titanium dioxide (TiO2). The Zn(OH)2 was formed at the ZnO surface and ZnO become inactive as a photocatalyst when ZnO is present in the solution. Therefore, we prepared synthesized ZnO nanoaprticles that were immersed in the water and dried in the oven. After that, we measured photocatalytic activities of prepared samples and find the cause of their phtocatalytic activity changes. The characterization of ZnO nanoparticles were analyzed by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and BET test. Also we defined the photocatalytic activity of ZnO nanoparticles using UV-VIS Spectroscopy. And we explained changing of photocatalytic activity after the water treatment using X-ray Photoelectron Spectroscopy (XPS).

• 한국진공학회지
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• 제18권5호
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• pp.394-401
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• 2009

본 논문은 ZnO 분말 타겟을 스퍼터링하여 glass 기판 위에 증착한 ZnO 박막의 구조적, 광학적 특성을 보고한다. 소결된 ZnO ceramic target을 사용하는 보통의 radio-frequency magnetron sputtering과 달리 본 연구에서는 전처리과정이 필요하지 않은 ZnO 분말 target을 사용하였다. ZnO 박막은 wurtzite (0002) 우선배향면으로 성장하였다. 초기의 ZnO 박막은 매우 평평한 층구조로 증착되었고, 두께가 증가함에 따라 섬구조로 전이하였다. 400-1000 nm 광원에 대하여 평균 88% 이상의 광투과도를 나타내었으며, 220 nm 시편의 경우, 3.23 eV의 near bandedge emission 흡수단을 측정하였다.

• 한국진공학회지
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• 제16권4호
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• pp.286-290
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• 2007

실리콘 기판위에 성장된 ZnO 나노막대에 NiO를 코팅하여 core-shell 형태의 나노막대를 제작하였다. 이렇게 제작된 나노막대를 수소 분위기에서 열처리한 결과 ZnO 나노막대 표면에 Ni 나노점들이 형성됨을 확인하였다. 이러한 여러 종류의 나노막대의 저온(5K)에서 광발광 (photoluminescence) 특성을 연구하였는데 $ZnO{\rightarrow}NiO-ZnO{\rightarrow}Ni$ 나노점-ZnO 순서로 시료가 변화함에 따라 속박된 exciton들의 전이 에너지와 진폭이 변화함을 확인하였다. ZnO에 비하여 NiO-ZnO 시료의 경우 받개에 속박된 exciton ($A^0X$) 전이가 크게 감소함을 보이나 Ni 나노점-ZnO 시료의 경우 $A^0X$ 전이가 가장 우세함을 보인다. 이러한 현상은 수소화 과정에서 침투한 Ni과 수소 이온이 주개로 작용하였기 때문이다.

• 한국세라믹학회지
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• 제30권3호
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• pp.199-205
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• 1993

Effects of grain size distribution on the breakdown voltage of ZnO varistors were investigated in the ZnO-Bi2O3-CoO-Sb2O3 and ZnO-Bi2O3-CoO-Sb2O3-Cr2O3 systems, respectively. The grain size was increased with increasing sintering temperature maintaining lognormal distribution in both systems. The width of grain size distribution of ZnO-Bi2O3-CoO-Sb2O3 system was narrower than that of ZnO-Bi2O3-CoO-Sb2O3 system. The breakdown voltage(Vb) was decreased by increasing sintering temperature(1000~135$0^{\circ}C$) and sintering time(0.5~5hr), due to the enhancement of ZnO grain growth. The current path of the ZnO varistor was dependent on the distribution of the largest grains (chains of long grains) between the electrodes.

• 한국재료학회지
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• 제15권10호
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• pp.678-682
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• 2005

We studied the possibility of $Zn_4O(Ac)_2(OH)$ formation as a precursor for ZnO nano particles in sol-gel method. Four different additives such as tetra methyl ammonium hydroxide, mono ethanol amine (MEA), LiOH, and $H_2O$ were used for zinc acetate dissolved in 2-methoxy ethanol. ZnO particles of 5-6 nm in size were observed. Existence of $Zn_4O(Ac)_6$ was not verified. $Zn_4O(Ac)_2(OH)$ molecules were observed and they were believed to be the precursors of ZnO. A peak at 275nm in UV-Vis analysis was observed In the case of MEA and $H_2O$ but no ZnO particles were detected in transmission electron microscopy.

• 한국세라믹학회지
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• 제30권9호
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• pp.723-730
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• 1993

The mechanism of formation of perovskite phase and the dielectric properties of PZMN[Pb(Zn, Mg)1/3Nb2/3O3] ceramics were examined using two different types of the columbite precursors, (Mg, Zn)Nb2O6 (MZN) and MgNb2O6＋ZnNb2O6 (MN＋ZN). The formatin of perovskite phase in PbO＋MN＋ZN system is characterized by an initial rapid formation of Mg-rich perovskite phase, followed by a sluggish formation of Zn-rich perovskite phase. On the other hand, thepyrochlore/perovskite transformation in the PbO＋MZN system proceeded uniformly with a spatial homogeneity. The degree of diffuseness of the rhombohedral/cubic phase transitionis higher in the PbO＋MN＋ZN system than in the PbO＋MZN specimen, indicating a broadened compositional distributjion of the B-site catons (Nb+5, Zn+2, Mg+2) in the PbO＋MN＋ZN system.