• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1408-1411
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• 2009

This paper describes organic acid-based wet chemical etching behaviors of amorphous Ga-doped zinc oxide (GZO) thin film sputter-deposited at low temperature (room temperature). Wet etch parameters such as etching time, temperature, and etchant concentration are investigated for formic and citric acid etchants, and their effects on the etch rate, etch residue and the feature of edge line are compared.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.525-528
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• 2001

ZnO:Al thin film can be used as a transparent conducting oxide(TCO) which has low electric resistivity and high optical transmittance for the front electrode of amorphous silicon solar cells and display devices. This study of electrical, crystallographic and optical properties of Al doped ZnO thin films prepared by Facing Targets Sputtering (FTS), where strong internal magnets were contained in target holders to confine the plasma between the targets, is described. Optimal transmittance and resistivity was obtained by controlling flow rate of O$_2$ gas and substrate temperature. When the of gas rate of 0.3 and substrate temperature 200$^{\circ}C$ , ZnO:Al thin film had strongly oriented c-axis and lower resistivity(<10$\^$-4/Ω-cm).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.300-303
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• 2001

BSCCO thin films are fabricated via a co-deposition process by an ion beam sputtering with an ultra-low growth rate, and sticking coefficients of the respective elements are evaluated. The sticking coefficient of Bi element exhibits a characteristic temperature dependence : almost a constant value of 0.49 below 730$^{\circ}C$ and decreases linearly with temperature over 730$^{\circ}C$. This temperature dependence can be elucidated from the evaporation and sublimation rates of bismuth oxide, Bi$_2$O$_3$, from the film surface. It is considered that the liquid phase of the bismuth oxide plays an important role in the Bi 2212 phase formation in the co-deposition process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.213-216
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• 1999

BSCCO thin films are fabricated via a co-deposition process by an ion beam sputtering with an ultra-low growth rate, and sticking coefficients of the respective elements are evaluated. The sticking coefficient of Bi element exhibits a characteristics temperature dependence : almost a constant value of 0.49 below 730$^{\circ}C$ and decreases linearly with temperature over 730$^{\circ}C$. This temperature dependence can be elucidated from the evaporation and sublimation rates of bismuth oxide, Bi$_2$O$_3$ from the film surface. It is considered that the liquid phase of the bismuth oxide plays an important role in the Bi(2212) phase formation in the co-deposition process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.193-197
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• 2000

BSCCO thin films are fabricated via a co-deposition process by an ion beam sputtering with an ultra-low growth rate, and sticking coefficients of the respective elements are evaluated. The sticking coefficient of Bi element exhibits a characteristic temperature dependence : almost a constant value of 0.49 below 73$0^{\circ}C$ and decreases linearly with temperature over 73$0^{\circ}C$. This temperature dependence can be elucidated from the evaporation and sublimation rates of bismuth oxide, Bi$_2$O$_3$, from the film surface. It is considered that the liquid phase of the bismuth oxide plays an important role in the Bi(2212) phase formation in the co-deposition process.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.97.2-97.2
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• 2011

Pt-Ru and Pt-Ni bimetallic catalysts were prepared and tested for heavy hydrocarbon reforming. Metals were supported on CGO($Ce_{0.8}Gd_{0.2}O_{2.0-x}$) by incipient wetness method. The prepared catalysts were characterized by Temperature programmed reduction(TPR). Oxidative steam reforming of n-dodecane was conducted to compare the activity of the catalysts. The reforming temperature was varied from $500^{\circ}C$ to $800^{\circ}C$ at fixed $O_2$/C of 0.3, $H_2O$/C of 3.0 and GHSV of 5,000/h.Reduction peaks of metal oxide, surface CGO and bulk CGO were detected. Reduction temperature of metal oxide decreased over the bi-metallic catalysts. It is considered that interaction between metals leads to decrease interaction between metal and oxygen. On the other hands, reduction temperatures of surface CGO were dectected in the order of Pt-Ru > Pt-Ni > Pt. low reduction temperatures of surface CGO indicates the low activation energy for oxygen ion conduction to metal. Oxygen ion conduction is known as de-coking mechanism of ionic conducting supports such as CGO. In activity test, fuel conversion was in the same order of Pt-Ru > Pt-Ni > Pt. Especially, 100% of fuel conversion was obtained over Pt-Ru catalysts at $500^{\circ}C$.

• Journal of Biomedical Engineering Research
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• v.43 no.4
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• pp.219-229
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• 2022

In this study, we propose a miniaturized micro-ceramic heater device. After screen-printing a silver paste between pre-sintered two aluminum oxide plates to integrate a heating circuit, the device was fabricated through a low-temperature sintering process. In order to configure the optimal heating circuit integration condition, the output current evaluation and heating test were performed according to the number of screen prints of the silver paste at various voltages. A silver paste-based heating circuit printed with a line width of 200 ㎛ and a thickness of 60 ㎛ was successfully integrated on a pre-sintered alumina substrate through a low-temperature sintering process. In the case of the 5 times printed device, the thermal response showed a response rate of 18.19 ℃/sec. To demonstrate feasibility of the proposed device in the medical field, such as bio-tissue suturing and hemostasis, a voltage was applied to pig tissue in the device to test tissue change due to heat generated from the device. These results show the possibility that the proposed small ceramic heater could be used in the medical field based on its excellent temperature response.

• Journal of Powder Materials
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• v.29 no.5
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• pp.357-362
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• 2022

The low-temperature sinterability of TiO₂-CuO systems was investigated using a solid solution of SnO₂. Sample powders were prepared through conventional ball milling of mixed raw powders. With the SnO₂ content, the compositions of the samples were Ti_1-xSn_xO₂-CuO(2 wt.%) in the range of x ≤ 0.08. Compared with the samples without SnO₂ addition, the densification was enhanced when the samples were sintered at 900℃. The dominant mass transport mechanism seemed to be grain-boundary diffusion during heat treatment at 900℃, where active grain-boundary diffusion was responsible for the improved densification. The rapid grain growth featured by activated sintering was also obstructed with the addition of SnO₂. This suggested that both CuO as an activator and SnO₂ dopant synergistically reduced the sintering temperature of TiO₂.

• Journal of Sensor Science and Technology
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• v.24 no.1
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• pp.15-21
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• 2015

Transparent and conductive multilayer thin films consisting of three alternating layers FZTO/Ag/$WO_3$ have been fabricated by radio-frequency (RF) sputtering for the applications as transparent conducting oxides and the structural and optical properties of the resulting films were carefully studied. The single layer fluorine doped zinc tin oxide (FZTO) and tungsten oxide ($WO_3$) films grown at room temperature are found to have an amorphous structure. Multilayer structured electrode with a few nm Ag layer embedded in FZTO/Ag/$WO_3$ (FAW) was fabricated and showed the optical transmittance of 87.60 % in the visible range (${\lambda}=380{\sim}770nm$), quite low electrical resistivity of ${\sim}10^{-5}{\Omega}cm$ and the corresponding figure of merit ($T^{10}/R_s$) is equivalent to $3.0{\times}10^{-2}{\Omega}^{-1}$. The resultant power conversion efficiency of 2.50% of the multilayer based OPV is lower than that of the reference commercial ITO. Asymmetric D/M/D multilayer is a promising transparent conducting electrode material due to its low resistivity, high transmittance, low temperature deposition and low cost components.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.187-187
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• 2012

Solution-processed metal-alloy oxides such as indium zinc oxide (IZO), indium gallium zinc oxide (IGZO) has been extensively researched due to their high electron mobility, environmental stability, optical transparency, and solution-processibility. In spite of their excellent material properties, however, there remains a challenging problem for utilizing IZO or IGZO in electronic devices: the supply shortage of indium (In). The cost of indium is high, what is more, indium is becoming more expensive and scarce and thus strategically important. Therefore, developing an alternative route to improve carrier mobility of solution-processable ZnO is critical and essential. Here, we introduce a simple route to achieve high-performance and low-temperature solution-processed ZnO thin film transistors (TFTs) by employing alkali-metal doping such as Li, Na, K or Rb. Li-doped ZnO TFTs exhibited excellent device performance with a field-effect mobility of $7.3cm^2{\cdot}V-1{\cdot}s-1$ and an on/off current ratio of more than 107. Also, in case of higher drain voltage operation (VD=60V), the field effect mobility increased up to $11.45cm^2{\cdot}V-1{\cdot}s-1$. These all alkali metal doped ZnO TFTs were fabricated at maximum process temperature as low as $300^{\circ}C$. Moreover, low-voltage operating ZnO TFTs was fabricated with the ion gel gate dielectrics. The ultra high capacitance of the ion gel gate dielectrics allowed high on-current operation at low voltage. These devices also showed excellent operational stability.