• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.350-350
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• 2011

ZnO는 II-VI족 화합물 반도체로서 3.37 ev의 band gap energy와 60 mv의 exciton binding energy를 가지며 차세대 소자로 다양한 분야에서 연구되어지고 있다. ZnO 박막과는 다르게 ZnO nano structure는 효율성과 특성 향상의 이점으로 태양전지와 투명전극 소자에 많은 연구가 되고 있으며 UV 레이저, 가스센서, LED, 압전소자, Field Emitting Transistor (FET) 등 다양한 응용분야에서 연구되고 있다. 본 연구에서는 유리 기판 위에 RF Magnetron sputtering법을 이용해 ZnO buffer layer를 다양한 두께(~1,000${\AA}$)로 증착한 뒤, Zn powder (99.99%)를 지름 2inch 석영관 안에 넣어 Thermal furnace장비를 이용하여 Thermal Evaporation법으로 약 500$^{\circ}C$에서 30분 동안 촉매 없이 성장 하였다. 수직성장된 ZnO 나노 구조체의 특성을 전계방출주사전자현미경(SEM), X-선 회절패턴(XRD), UV-spectra를 이용하여 분석하였다. SEM 분석을 통하여 ZnO buffer layer위에 성장된 ZnO 나노 구조체는 직경이 약 ~50 nm, 길이가 ~2 um까지 성장을 보였으며, XRD 측정결과, ZnO 우선 성장 방향(002)을 확인하였다. 두 가지 측정을 통하여 ZnO buffer layer의 유무에 따라 성장 특성이 향상되었음을 확인하였으며, 이는 buffer layer가 seed 역할을 한 것으로 사료된다. UV-spectra 측정을 통하여 가시광 영역(400~780 nm)에서 60%대의 투과도를 보여 가시광 영역에서 투명성을 요구하는 전자 소자 및 광소자 등에 적용 가능성을 확인하였다. 이 연구를 통하여 우수한 투과도를 가지며 유리 기판위에 수직성장된 ZnO 나노구조체는 태양전지와 플렉서블 디스플레이 등 다양한 활용 분야를 제시할 수 있다.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.2
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• pp.173-180
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• 2004

Nano sized ZnO particle as 20-30nm applies for material, pigments, rubber additives, gas sensors, varistors, fluorescent substance as well as new material such as photo-catalyst, sensitizer, fluorescent material. ZnO with a particle size in the range 20-30nm has provided to be an excellent UV blocking material in the cosmetics industry, which can be used in sunscreen product to enhance the sun protection factor and natural makeup effect. But pure ZnO particles application limits for getting worse wearing feeling. We make high-functional inorganic-composite that coated with nano-ZnO on the plate-type particle such as sericite, boron nitride and bismuthoxychloride. In this experiment, we synthesized composite powder using hydrothermal precipitation method. The starting material was ZnCl$_2$ Precipitation materials were used hexamethylenetetramine(HMT) and urea. We make an experiment with changing as synthesis factors that are concentrations of starting material, precipitation materials, nuclear formation material, reaction time, and reaction temperature. We analyzed composite powder's shape, crystallization and UV-blocking ability with FE-SEM, XRD, FT-IR, TGA-DTA, In vitro SPF test. The user test was conducted by product's formulator. In the results of this study, nanometer sized ZnD was coated regardless of the type of plate-powder at fixed condition range. When the coated plate-powders were applied in pressed powder product, the glaze of powder itself decreased, but natural make-up effect, spreadability, and adhesionability were increased.

• Journal of the Semiconductor & Display Technology
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• v.9 no.3
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• pp.75-78
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• 2010

In this study we investigated the electrical properties of ZnO-based MOS capacitor with $HfO_2$ as the gate dielectric. MIM capacitor, which uses either $HfO_2$ or $Al_2O_3$ as the dielectric layer, is also studied to understand the dependency of the dielectrics on the preparation conditions. It was found that thinner $HfO_2$ films yield better electrical properties, namely lower leakage current and higher breakdown electric field. These properties were observed to deteriorate when subsequently annealed. Capacitance in the depletion region of MOS capacitor was found to increase with UV ozone treatment time up to 60min. However, when the treatment time was extended to 120min, the trend is reversed. The 'threshold voltage' was also observed to positively shift with UV ozone treatment time up to 60min. The shift apparently saturated for longer treatment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1013-1016
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• 2005

ZnO nanostructure was fabricated by catalyst-free method using Zn powder in air. The growth temperature was controlled from 450$^{\circ}$C to 600$^{\circ}$C, and the structural and optical properties were investigated by scanning electron microscopy (SEM), photoluminescence (PL), energy dispersive X-ray spectroscopy (EDX) and cathodoluminescence (CL). From all samples both ZnO tetrapods and clusters were observed. No significant dispersion was observed from the ZnO tetrapods, however, ZnO clusters show considerable change in density and size. From the EDX results, atomic composition difference was found. The clusters have O-deficiencies, while tetrapods have stoichiometric composition. Strong luminescence was observed at room temperature. From room temperature PL, UV emission at 380 nm and green emission at 500 nm were observed, and the intensity ratio ($I_{uv}/I_{green}$) increased as growth temperature increases. CL measurements show that the UV emission is closely related with tetrapods and the green emission is dominated from the clusters.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.292-292
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• 2010

Among the semiconducting materials, ZnO has considerably attracted attention over the past few years due to the high activities in removing organic contaminants created from industry. In this work, ZnO nanoparticles were synthesized by spray pyrolysis method using the zinc acetate dihydrate as starting material at various synthesis temperatures. The structures of the synthesized ZnO were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer, Emmett & Teller (BET), Fourier Transformation Infrared (FT-IR), and UV-vis spectroscopy. The Miller indices of XRD patterns indicate that the synthesized ZnO nanoparticles showed a hexagonal wurtzite structure. With increasing synthesis temperature, the mean diameter of ZnO nanoparticles increased, and their crystallinity was improved. Also, the photocatalytic activity of ZnO was studied by the photocatalytic degradation of methyleneblue (MB) under UV irradiation (365 nm) at room temperature. The results show that the photocatalytic efficiency of ZnO nanoparticles was enhanced by increasing synthesis temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.95-98
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• 1999

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition technique using a Nd:YAG laser with the wavelength of 355 nm. In order to investigate the effect of the deposition conditions on the properties of ZnO thin films at an oxygen pressure of 350 mTorr, the experiment has been Performed at various substrate temperatures in the range of 20$0^{\circ}C$ to $700^{\circ}C$. According to XRD, (002) textured ZnO films of high crystalline quality have been obtained and the intensity of UV emission was the highest at 40$0^{\circ}C$ substrate temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.8
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• pp.508-513
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• 2017

Ultraviolet (UV) photodetectors are used in various industries and fields of research, including optical communication, flame sensing, missile plume detection, astronomical studies, biological sensors, and environmental research. However, general UV detectors that employ Schottky junction diodes and p-n junctions have high fabrication cost and low quantum efficiency. In this study, we investigated the characteristics of materials used to manufacture UV photodetectors in a low-cost solution process that requires easy fabrication of flexible substrates. We fabricated p-type NiO and n-type ZnO substrates with wide band gap by the sol-gel method and compared the characteristics of substrates prepared under different spin-coating and heat-treatment conditions.

• Elastomers and Composites
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• v.45 no.3
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• pp.206-211
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• 2010

Zinc oxide(ZnO) nanoparticles were synthesized by reacting an aqueous-alcoholic zinc nitrate solution to sodium hydroxide under ultrasonic irradiation at room temperature. The fullerene($C_{60}$) and ZnO nanoparticles were heated individually in an electric furnace for two hours at $700^{\circ}C$. The morphology and optical properties of the $C_{60}$ and ZnO nanoparticles were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and ultraviolet/visible (UV-vis) spectroscopy. The photocatalytic activity of the heated and unheated the $C_{60}$ and ZnO nanoparticles for the decomposition of methylene blue(MB), methyl orange(MO) and rhodamine B(RhB) was examined using UV-vis spectroscopy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.3
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• pp.230-234
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• 2009

Hydrogen and Oxygen plasma treatments have been done on sonochemical grow ZnO nanorods by varying treatment temperature and time, The changes(position and intensity) in ultraviolet(UV) peaks and green peaks of photoluminescence(PL) spectroscopy have been measured, Experimental results showed; i) in the case of hydrogen plasma treatment, the blue shift of UV peak and the increase of PL intensity of the UV peak were observed as the increase of the process time and temperature, ii) in the case of oxygen plasma treatment, the red shift of green peak was observed and the ratio of $I_{Green}/I_{UV}$ was also increased, as the increase of the process time and the temperature.

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.262-267
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• 2003

The heteroepitaxial ZnO thin film on sapphire (0001) substrate was prepared by an off-axis Radio Frequency(RF) magnetron sputtering. The crystallinity of ZnO thin film was affected by deposition pressure, RF power, and substrate temperature. High quality heteroepitaxial ZnO thin film was obtained when the kinetic energy of sputtered particles is well harmonized with the surface mobility. In the result of Photoluminescence(PL) of heteroepitaxial ZnO thin film, Ultraviolet(UV) emissions at 3.36 and 3.28 eV were observed at low(17 K) and Room Temperature(RT). respectively. As the ZnO thin film was annealed in O$_2$ambient, the crystallinity was improved while UV emission was drastically decreased.