• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.17-20
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• 2001

Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectric were fabricated, and nitrogen distribution and bonding species which contributing memory characteristics were analyzed. Also, memory characteristics of devices according to anneal temperatures were investigated. The devices were fabricated by 0.35$\mu\textrm{m}$ retrograde twin well CMOS processes. The processes could be simple by in-situ process of nitridation anneal and reoxidation. The nitrogen distribution and bonding state of gate dielectric were investigated by Dynamic Secondary Ion Mass Spectrometry(D-SIMS), Time-of-Flight Secondary ton Mass Spectrometry(ToF-SIMS), and X-ray Photoelectron Spectroscopy(XPS). Nitrogen concentrations are proportional to nitridation anneal temperatures and the more time was required to form the same reoxidized layer thickness. ToF-SIMS results show that SiON species are detected at the initial oxide interface and Si$_2$NO species near the new Si-SiO$_2$ interface that formed after reoxidation. As the anneal temperatures increased, the device showed worse retention and degradation properties. These could be said that nitrogen concentration near initial interface is limited to a certain quantity, so excess nitrogen are redistributed near the Si-SiO$_2$ interface and contributed to electron trap generation.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.318.2-318.2
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• 2013

기존의 염료감응형 태양전지(Dye Sensitized Solar Cells; DSSCs)는 최대 효율 11~12%의 광전변환효율을 가지고 있다. 이러한 한계를 극복하기 위해서 광흡수 층 최적화, 상대전극의 촉매성 증대, 전해질의 산화 환원 반응 최적화 등의 많은 연구가 이루어지고 있다. 본 연구에서는 DSSCs의 광전변환효율을 증가시키고자 기존의 투명전극 및 기판으로 사용되는 FTO(Fluor-doped Tin Oxide)를 GZO(Gallium-doped Zinc Oxide)를 사용하여 투명전극기판에 따른 계면 저항, 전류손실 등 DSSCs에 미치는 영향을 분석하였다. 본 연구에 사용된 FTO는 ${\sim}7{\Omega}/{\square}$의 면저항과 80%이상의 투과도를 갖고 있으나 Ion-Sputtering 법으로 증착된 GZO는 열처리 과정을 통하여 $3{\sim}4{\Omega}/{\square}$의 면 저항을 나타내고 80%이상의 우수한 투과도를 가지고 있다. 이러한 두 기판의 특성 비교를 위해, UV-Visble Spectrophotometer를 사용하여 광학적 특성을 분석하고, SEM(Scanning Electron Microscope), AFM(Atomic Force Microscope)를 사용하여 표면 특성을 평가하였다. 또한 전기적 특성을 분석하기 위하여 4-Point-probe를 이용하여 면 저항을 측정하였고, DSSCs의 효율 및 Fill Factor를 분석하기 위하여 Solar Simulator의 I-V measurement를 이용하였다.

• Journal of Powder Materials
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• v.29 no.6
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• pp.485-491
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• 2022

Lithium lanthanum titanium oxide (LLTO) is a promising ceramic electrolyte because of its high ionic conductivity at room temperature, low electrical conductivity, and outstanding physical properties. Several routes for the synthesis of bulk LLTO are known, in particular, solid-state synthesis and sol-gel method. However, the extremely low ionic conductivity of LLTO at grain boundaries is one of the major problems for practical applications. To diminish the grain boundary effect, the structure of LLTO is tuned to nanoscale morphology with structures of different dimensionalities (0D spheres, and 1D tubes and wires); this strategy has great potential to enhance the ion conduction by intensifying Li diffusion and minimizing the grain boundary resistance. Therefore, in this work, 0D spherical LLTO is synthesized using ultrasonic spray pyrolysis (USP). The USP method primarily yields spherical particles from the droplets generated by ultrasonic waves passed through several heating zones. LLTO is synthesized using USP, and the effects of each precursor and their mechanisms as well as synthesis parameters are analyzed and discussed to optimize the synthesis. The phase structure of the obtained materials is analyzed using X-ray diffraction, and their morphology and particle size are analyzed using field-emission scanning electron microscopy.

• Resources Recycling
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• v.28 no.6
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• pp.54-63
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• 2019

This study investigated on the compressive strength and the length change test with using the waste glass and graphene oxide for recycling the waste glass as the aggregate. Curing on 3-day and 7-day, the compressive strength was enhanced as the usage of waste glass was increased. Especially, the huge difference in the compressive strength was observed when the amount of substituting on the waste glass was used on 10~50%. With 50% of waste glass condition, the compressive strength was portionally enhanced as the usage of graphene oxide was increased and its value was 42.6 N/㎟ with 0.2% of graphene oxide. In terms of the length change test, the use of high content of waste glass led length change value to increase, but it was dropped down as the portion of waste glass was above 50%. Furthermore, in the case of using 50% of waste glass, the use of high amount of graphene oxide tended to decrease the length change value. That is, graphene oxide may contribute on boosting the cement hydration reaction and blocking the ion's movement.

• Journal of Surface Science and Engineering
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• v.50 no.3
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• pp.147-154
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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. 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 electrolyte. 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.

• Applied Biological Chemistry
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• v.41 no.4
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• pp.241-245
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• 1998

Two oxidation states of chromium commonly occur in natural soil/water systems, Cr(III) and Cr(VI). The oxidized form, Cr(VI), exists as the chromate ion and is more mobile and toxic than Cr(III). Therefore oxidation of Cr(III) by various Mn-oxides in natural systems is a very important environmental concern. Organic substances can inhibit the Cr(III) oxidation by binding, Cr(III) strongly and also by dissolving Mn-oxides. Most of Cr(III) oxidation studies were carried out using in vitro systems without organic substances which exist in natural soil/water systems. In this study effect of organic acids - oxalate and pyruvate - on Cr(III) oxidation by $birnessite({\delta}-MnO_2)$ was examined. The two organic acids significantly inhibited Cr(III) oxidation by birnessite. Oxalate showed more significant inhibition than pyruvate. As solution pH was lowered in the range of 3.0 to 5.0, the Cr(III) oxidation was more strongly depressed. Addition of more organic acids reduced the Cr(III) oxidation mare extensively. Different inhibition effects by the organic acids could be due to their ability of reductive dissolution of Mn-oxides and/or Cr(III) binding. Organic acids dissolved Mn-oxide during the Cr(III) oxidation by the oxide, Dissolution by oxalic acid was much greater than that by pyruvate, and the dissolution was more extensive at lower pH. Inhibition of Cr(III) oxidation was parallel to the dissolution of Mn-oxide by organic acids. Although the effect of Cr(III) binding by organic acids on Cr(III) oxidation is not known yet, Mn-oxide dissolution by organic acids could be a main reason for the inhibition of Cr(III) oxidation by Mn-oxide in presence of organic acids. Thus oxidation of Cr(III) to Cr(VI) by various Mn-oxides in natural systems could be much less than the oxidation estimated by in vitro studies with only Cr(III) and Mn-oxides.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.4
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• pp.13-19
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• 2010

MOSFET with deuterium-incorporated gate oxide shows enhanced reliability compared to conventional MOSFET. We present an alternative process whereby deuterium is delivered to the location where the gate oxide reside by an implantation process. Deuterium ions were implanted using two different energies to account for the topography of the overlaying layers and placing the D peak at the top of gate oxide. A short anneal at forming gas was performed to remove the D-implantation damage. We have observed that deuterium ion implantation into the gate oxide region can successfully remove the interface states and the bulk defects. But the energy and the dose of the deuterium implant need to be optimized to maintain the Si substrates dopant activation, while generating deuterium bonds inside gate oxide. CV and IV characteristics studies also determined that the deuterium implant dose not degrade the transistor performance.

• Journal of Electrochemical Science and Technology
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• v.11 no.1
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• pp.60-67
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• 2020

In this study, copper (II) oxide powder for electroplating was prepared by recovering CuCl₂ from NaClO₃ type etching wastes via recovered non-sintering two step chemical reaction. In case of alkali copper carbonate [mCuCo₃·nCu(OH)₂], first reaction product, CuCo₃ is produced more than Cu(OH)₂ when the reaction molar ratio of sodium carbonate is low, since m is larger than n. As the reaction molar ratio of sodium carbonate increased, m is larger than n and Cu(OH)₂ was produced more than CuCO₃. In the case of m has same values as n, the optimum reaction mole ratio was 1.44 at the reaction temperature of 80℃ based on the theoretical copper content of 57.5 wt. %. The optimum amount of sodium hydroxide was 120 g at 80℃ for production of copper (II) oxide prepared by using basic copper carbonate product of first reaction. At this time, the yield of copper (II) oxide was 96.6 wt.%. Also, the chloride ion concentration was 9.7 mg/L. The properties of produced copper (II) oxide such as mean particle size, dissolution time for sulfuric acid, and repose angle were 19.5 mm, 64 second, and 34.8°, respectively. As a result of the hole filling test, it was found that the copper oxide (II) prepared with 120 g of sodium hydroxide, the optimum amount of basic hydroxide for copper carbonate, has a hole filling of 11.0 mm, which satisfies the general hole filling management range of 15 mm or less.

• Journal of Sensor Science and Technology
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• v.6 no.3
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• pp.200-206
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• 1997

Using $SiCl_{2}H_{2}$, $NH_{3}$ and $N_{2}O$, we have fabricated silicon oxynitride ($Si_{x}O_{y}N_{z}$) layers on thermally oxidized silicon wafer by low pressure chemical vapor deposition. Three different compositions were achieved by controlling gas flow ratios($NH_{3}/N_{2}O$)) to 0.2, 0.5 and 2 with fixed gas flow of $SiCl_{2}H_{2}$. Ellipsometry and high frequency capacitance-voltage(HFCV) measurements were adapted to investigate the difference of the refractive index, dielectric constant, and composition, respectively. Regardless of nitride content, silicon oxynitrides had similar stability to silicon nitrides. The relative standing of alkali ion sensitivity in silicon oxynitride layers was influenced by nitride content. The better alkali ion-sensitivity was achieved by increasing oxide content in bulk of silicon oxynitrides.

• Korean Journal of Materials Research
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• v.29 no.12
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• pp.774-780
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• 2019

The performance of Li-ion hybrid supercapacitors (asymmetric-type) depends on many factors such as the capacity ratio, material properties, cell designs and operating conditions. Among these, in consideration of balanced electrochemical reactions, the capacity ratio of the negative (anode) to positive (cathode) electrode is one of the most important factors to design the Li-ion hybrid supercapacitors for high energy storing performance. We assemble Li-ion hybrid supercapacitors using activated carbon (AC) as anode material, lithium manganese oxide as cathode material, and organic electrolyte (1 mol L^-1 LiPF₆ in acetonitrile). At this point, the thickness of the anode electrode is controlled at 160, 200, and 240 ㎛. Also, thickness of cathode electrode is fixed at 60 ㎛. Then, the effect of negative and positive electrode ratio on the electrochemical performance of AC/LiMn₂O₄ Li-ion hybrid supercapacitors is investigated, especially in the terms of capacity and cyclability at high current density. In this study, we demonstrate the relationship of capacity ratio between anode and cathode electrode, and the excellent electrochemical performance of AC/LiMn₂O₄ Li-ion hybrid supercapacitors. The remarkable capability of these materials proves that manipulation of the capacity ratio is a promising technology for high-performance Li-ion hybrid supercapacitors.