• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.96.2-96.2
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• 2017

This research was conducted to investigate the electrochemical properties of the thin air-formed oxide film-covered AZ31 Mg alloy. In this work, native air-formed oxide films on AZ31 Mg alloy samples were prepared by knife-abrading method and the changes in the electrochemical properties of the air-formed oxide film were investigated in seven different electrolytes containing the following anions $Cl^-$, $F^-$, $SO{_4}^{2-}$, $NO_3{^-}$, $CH_3COO^-$, $CO{_3}^{2-}$ and $PO{_4}^{3-}$. It was observed from open circuit potential (OCP) transients that the potential initially decreased before gradually increasing again in the solutions containing only $CO{_3}^{2-}$ or $PO{_4}^{3-}$ ions, indicating the dissolution or transformation of the native air-formed oxide film into new more protective surface films. The Nyquist plots obtained from electrochemical impedance spectroscopy (EIS) showed that there was growth of new surface films with immersion time on the air-formed oxide film-covered specimens in all the electrolytes; the least resistive surface films were formed in fluoride and sulphate baths whereas the most protective film was formed in phosphate bath. The potentiodynamic polarization curves illustrated that passive behaviour of AZ31 Mg alloy under anodic polarization appears only in $CO{_3}^{2-}$ or $PO{_4}^{3-}$ ions containing solutions and at more than $-0.4V_{Ag/AgCl}$ in $F^-$ ion containing solution.

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.11a
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• pp.152-153
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• 1996

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.537-538
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• 2010

• Korean Journal of Materials Research
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• v.14 no.6
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• pp.402-406
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• 2004

$WSi_2$, $TiSi_2$, $CoSi_2$, and $TaSi_2$ are general silicides used today in semiconductor devices. $WSi_2$ thin films have been proposed, studied and used recently in CMOS technology extensively to reduce sheet resistance of polysilicon and $n^{+}$ region. However, there are several serious problems encountered because $WSi_2$ is oxidized and forms a native oxide layer at the interface between $WSi_2$ and $Si_3$$N_4$. In this study, we have introduced 20 $slm-N_2$ gas from top to bottom of the furnace in order to control native oxide films between $WSi_2$ and $Si_3$$N_4$ film. In resulting SEM photographs, we have observed that the native oxide films at the surface of $WSi_2$ film are removed using the long injector system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.245-248
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• 2020

The wettability of silicon carbide (SiC) crystal, which has 6H-SiC and 4H-SiC regions prepared using the physical vapor transport (PVT) method, is quantitatively analyzed using dispensed deionized (DI) water droplets. Regardless of the polytypes in SiC, the average of five contact angle measurements showed a difference of about 6° between the Si-face and C-face. The contact angle on the Si-face (C-face) is measured after the removal of the native oxide using BOE (6:1), and revealed a significant decrease of the contact angle from 74.9° (68.4°) to 47.7° (49.3°) and from 75.8° (70.2°) to 51.6° (49.5°) for the 4H-SiC and 6H-SiC regions, respectively. The contact angle of the Si-face recovered over time during room temperature oxidation in air; in contrast, that of the C-face did not recover to the initial value. This study shows that the contact angle is very sensitive to SiC surface polarity, specific surface conditions, and process time. Contact angle measurements are expected to be a rapid way of determining the surface polarity and wettability of SiC crystals.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.8
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• pp.31-36
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• 2004

we developed a technique to manufacture more reliable polycrystalline silicon TFT-LCDs using UV cleaning and buffered oxide etch(BOE) cleaning which remove the native oxide of the silicon surface before laser annealing. To investigate the effects of pre-treatments on the surface roughness of polycrystalline silicon, we measured atomic force microscopy(AFM). Also the electrical characteristics of polysilicon TFTs, breakdown characteristic and switching Performance, were tested for various pre-treatment conditions and several locations in large glass substrate.

• Korean Journal of Food Science and Technology
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• v.37 no.1
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• pp.44-49
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• 2005

Physicochemical properties of hydroxypropylated rice starches were investigated. Swelling power of hydroxypropylated rice starch increased at relatively lower temperature than native rice starch. Solubility of hydroxypropylated rice starch was lower (1.9-13.4%) than that of native rice starch (2.2-13.8%), and increased with increasing amount of propylene oxide. Pasting temperature ($66.2-70.8^{\circ}C$) and peak viscosity (2,843-3,395cp) of hydroxypropylated rice starch were lower than those of native starch ($71.6^{\circ}C,\;3,976\;cp$) and decreased with increasing amount of propylene oxide, regardless of reaction time. DSC thermal transitions of hydroxypropylated rice starches shifted toward lower temperature. Amylopectin-melting enthalpy of hydroxypropylated rice starch decreased (11.8-9.8J/g) with increasing amount of propylene oxide and was lower than that of native starch (11.9 J/g). These results indicate hydroxypropylation lowered swelling power and gelatinization temperatures of rice starch, because internal bonds of rice starch molecules were sterically weaken by substituted hydroxypropyl groups.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.6
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• pp.627-634
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• 2018

Gallium-based liquid metal, e.g., eutectic gallium-indium (EGaIn), is highly attractive as an electrode material for flexible and stretchable devices. On the liquid metal, oxide layer is spontaneously formed, which has a wide band-gap, and therefore is electrically insulating. In this paper, we fabricate a capacitor based on eutectic gallium-indium (EGaIn) liquid metal and investigate its cyclic voltammetry (CV) behavior. The EGaIn capacitor is composed of two EGaIn electrodes and electrolyte. CV curves reveal that the EGaIn capacitor shows the behavior of electric double-layer capacitors (EDLC), where the oxide layers on the EGaIn electrodes serves as the dielectric layer of EDLC. The oxide thicker than the spontaneously-formed native oxide decreases the capacitance of the EGaIn capacitor, due to increased voltage loss across the oxide layer. The EGaIn capacitor without oxide layer exhibits unstable CV curves during the repeated cycles, where self-repair characteristic of the oxide was observed. Finally, the electrolyte concentration is optimized by comparing the CV curves at various electrolyte concentrations.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.84-85
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• 2012

Poly(ethylene glycol) (PEG)는 Hydrophilic하면서 독성이 없기 때문에 약물과 관련된 연구가 많이 이루어졌다. 초기 PEGylation은 약물과 관련된 연구가 주를 이루었지만, 최근에는 PEG의 non-fouling 효과 때문에 표면에 적용하여 biomedical 장비에 세포나 단백질이 붙지 않도록 하는 개질하는 방법에 많은 연구가 진행되고 있다. Native Chemical Ligation(N.C.L.)은 단백질을 합성할 때, Protecting group을 사용하지 않고 반응을 진행시킬 수 있기 때문에 많은 주목을 받고 있다. N.C.L.은 합성한 두 물질이 Thioester와 Cysteine을 갖고 있으면, mild condition에서 amide bond를 형성하면서 반응이 쉽게 진행되기 때문에 다양한 분야에 적용할 수 있다. 이 논문에서 우리는 N.C.L.을 표면에 적용시켰으며 그 중 한 예로 표면 PEGylation진행하였다.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.193-195
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• 1988

The native oxide films were thermally and anodically formed on the n-GaP substrates grown by SSD method and measured this oxide thickness and the chemical composition and the electrical properties with formation condition. The chemical composition of themally oxidized GaP film was composed of mostly $GaPO_4$ at temperature below $800^{\circ}C$ and mostly $\beta-Ga_{2}O_{3}$ above $800^{\circ}C$. But The chemical composition of anodically oxidized GaPfilm was composed of the mixture of $Ga_{2}O_{3}$ and $P_{2}O_{5}$. The barrier height of Al/oxide/n-Gap which was formed at $700^{\circ}C$ by thermal oxidation method were 1.10eV, 1.03eV in Current-Voltage measurement. Interface charge density were $4{\times}10^{12}q(C/cm^2)$ and $3{\times}10^{12}q(C/cm^2)$ in Capacitance-Voltage measurement respectively.