• Journal of the Korean Applied Science and Technology
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• v.19 no.1
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• pp.43-48
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• 2002

We carried out this subject to observe photoisomerization using 1,2-dioleoyl-sn- glycero-3-phosphocholine(DOPC) mixed with fatty acid containing azobenzene group which has reversible to cis-trans by light irradiation. Spreading solutions for the LB films were prepared in chloroform($5.0{\times}10^{-5}$mol/L).We investigated the photoisomerization and property of the organic ultra thin film of fatty acid containing azobenzene was prepared on the hydrophilic ITO(idium tin oxide) glass plate by LB method. As a result, the absorption spectra of 8A5H and DOPC of mixture LB films was induced to photoisomerization by alternating irradiation of ultraviolet and visible light, because the condensation of pure azobenzene monolayers was loosened by the introduction of phospholipid into the monolayers, and the molecular high aggregation in pure azobenzene monolayers is also weakened by the introduction of phospholipid. We found that it was reversibly induced to cis-trans photoisomerization in several solvents and mixture LB films.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.705-716
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• 2017

In this study, Indium-Titanium hydroxide particle with 0.5, 1.0, 1.5 wt% of $TiO_2$ were synthesized by sol process and adding the base, ITiO(Indium Titanium Oxide) particles were obtained by gelling at $200^{\circ}C$ and $500^{\circ}C$. The ITiO particle's size with gel process at $200^{\circ}C$ was smaller than ITiO particle's size with gel process $500^{\circ}C$. The ITiO particle with gel process at $200^{\circ}C$ was used to fabricate dense ITiO target. ITiO targets with 0.5, 1.0, 1.5 wt% of $TiO_2$ were fabricated and used to obtain ITiO thin films onto glass by sputtering. Among those sputtered ITiOs' thin films, ITiO thin film with 0.4 % of $O_2$ and 0.5 wt% of $TiO_2$ showed the lowest specific resistance, highest charge mobility and lowest carrier concentration. It was found the light transmittance of the ITiO film were increased highly compared to light transmittance of ITO (Indium Tin Oxide) thin film over Infrared wavelength ranges.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.335-335
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• 2014

Over the past several years, transparent conducting oxides have been extensively studied in order to replace indium tin oxide (ITO). Here we report on fluorine doped zinc tin oxide (FZTO) films deposited on glass substrates by radio-frequency (RF) magnetron sputtering using a 30 wt% ZnO with 70 wt% SnO2 ceramic targets. The F-doping was carried out by introducing a mixed gas of pure Ar, CF4, and O2 forming gas into the sputtering chamber while sputtering ZTO target. Annealing temperature affects the structural, electrical and optical properties of FZTO thin films. All the as-deposited FZTO films grown at room temperature are found to be amorphous because of the immiscibility of SnO2 and ZnO. Even after the as-deposited FZTO films were annealed from $300{\sim}500^{\circ}C$, there were no significant changes. However, when the sample is annealed temperature up to $600^{\circ}C$, two distinct diffraction peaks appear in XRD spectra at $2{\Theta}=34.0^{\circ}$ and $52.02^{\circ}$, respectively, which correspond to the (101) and (211) planes of rutile phase SnO2. FZTO thin film annealed at $600^{\circ}C$ resulted in decrease of resistivity $5.47{\times}10^{-3}{\Omega}cm$, carrier concentration ~1019 cm-3, mobility~20 cm2 V-1s-1 and increase of optical band gap from 3.41 to 3.60 eV with increasing the annealing temperatures and well explained by Burstein-Moss effect. Change of work function with the annealing temperature was obtained by ultraviolet photoemission spectroscopy. The increase of annealing temperature leads to increase of work function from ${\phi}=3.80eV$ (as-deposited FZTO) to ${\phi}=4.10eV$ ($600^{\circ}C$ annealed FZTO) which are quite smaller than 4.62 eV for Al-ZnO and 4.74 eV for SnO2. Through X-ray photoelectron spectroscopy, incorporation of F atoms was found at around the binding energy of 684.28 eV in the as-deposited and annealed FZTO up to 400oC, but can't be observed in the annealed FZTO at 500oC. This result indicates that F atoms in FZTO films are loosely bound or probably located in the interstitial sites instead of substitutional sites and thus easily diffused into the vacuum from the films by thermal annealing. The optical transmittance of FZTO films was higher than 80% in all specimens and 2-3% higher than ZTO films. FZTO is a possible potential transparent conducting oxide (TCO) alternative for application in optoelectronics.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.789-794
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• 2015

In this study, we investigated the stability with respect to the Langmuir-Blodgett(LB) monolayer films of stearic acid and phospholipid(L-${\alpha}$-dimyristoylphosphatidyl choline, DMPC) mixture. LB films of stearic acid and DMPC monolayer were deposited by the LB method on the indium tin oxide(ITO) glass. The electrochemical properties measured by cyclic voltammetry with three-electrode system in $0.05N\;NaClO_4$ solution, -0.3 V initial, 1650 mV switching potential and -1350 mV final potential. As a result, monolayer LB films of stearic acid and phospholipid mixture was appeared on irreversible process caused by the oxidation current from the cyclic voltammogram. Diffusion coefficient (D) of stearic acid and DMPC mixture(molar ratio 1:1, 1:2, 1:3) was calculated $1.4{\times}10^{-3}$, $1.7{\times}10^{-3}$ and $1.6{\times}10^{-3}(cm^2/s)$ in $0.05N\;NaClO_4$ solution, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.465-465
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• 2011

In recent years, electrochemical supercapacitors have attracted much attention due to their high power density, long life cycles, and high efficiency. Some supercapacitors using CNTs have been reported, but there are several issues to be resolved for further development of CNT based supercapacitors. One issue is time consuming procedures to prepare CNT films, which may provide poor control of CNT uniformity over the large area of the substrates. Another is new electrolytes replacing the conventional liquid electrolytes in supercapacitors. In this work, We have successfully demonstrated that spray deposition method of multiwalled CNT films using gel electroytes could be promising for CNT-based supercapacitors on ITO substrates. Specific capacitances using gel electrolyte reached up to 1.5 F/g and 9 mF/$cm^2$, and internal resistance was 28 ${\Omega}$. Specific capacitances and internal resistance of supercapacitors with gel electrolyte were better than or comparable to those with liquid electrolytes($KNO_3$, $Na_2SO_4$), indicating that gel electrolytes could replace liquid counterparts in CNT-based supercapacitors. Combined with gel electrolyte, spray deposition method could provide low cost and easily scalable process for high performance supercapacitors using CNT films on ITO for applications in display devices.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1412-1413
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• 2006

In this research, an organic thin 13 passivation layer was newly adopted to prefect the organic layer from ambient moisture and oxygen. As the organic thin film passivation layer, poly methyl methacrylate thin films (ppMMA) were deposited using a plasma polymerization technique. In order to their passivation performance for OLEDs, water vapor transmission rate (WVTR) of the ppMMAs were analyzed and luminance-current-voltage (L-I-V)/luminance-time (L-T) characteristics of the OLEDs with and without ppMMA passivation layer were investigated. The OLEDs had a structure of ITO/TPD (HTL)/Alq3(EML&ETL)/Al. The OLED with ppMMA passivation layer showed improved L-T performance than that of without ppMMA passivation layer.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.134-134
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• 2012

We investigated the interface of poly (3-hexylthiophene) (P3HT) and C61-butyric acid methylester (PCBM) by using photoelectron spectroscopy (PES). These are the most widely used materials for bulk heterojunction (BHJ) organic solar cells due to their high efficiency. Study of the BHJ interfaces is difficult because the organic films are typically prepared by spin coating in ambient conditions. This is incompatible with the interface electronic structure probes such as PES, which requires ultrahigh vacuum conditions. Study of interface requires gradual deposition of thin films that is also incompatible with the spin coating process. In this work, we used electrospray vacuum deposition (EVD) technique to deposit P3HT and PCBM in high vacuum conditions. EVD allows us to form polymer thin films onto ITO substrate in a step-wise manner directly from solutions and to use PES without exposing the sample to the ambient condition. Although the morphology of the EVD deposited P3HT films observed by optical and atomic force microscopes is quite different from that of the spin coated ones, the valence region spectra were similar. PCBM was deposited on the P3HT film in a similar manner and the energy level alignment between these two materials was studied. We discuss the relation between Voc of P3HT:PCBM solar cell and HOMO-LUMO energy offset obtained in this study.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.319-325
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• 1999

Direct current(d.c.)leakage current voltage characteristics of radio-frequencymagnetron sputtered BaTa\sub 2\O\sub 6\ film capacitors with aluminum(A1) top and indium tin oxide (ITO) bottom electrodes have been investigatedas a function of applied field and temperature. In order to study surfacetreatment effect on the electrical characteristics of as-deposited film weperformed exposure of oxygen plasma on $BaTa_2O_6$ surface. d. c.current-voltage (I-V), bipolar pulse charge-voltage (Q-V), d. c. current-time (I-t) andcapacitance-frequency (C-f) analysis were performed on films. All ofthe films exhibita low leakage current, a high breakdown field strength (3MV/cm-4.5MV/cm), and high dielectric constant (20-30). From the temperature dependence of leakage current,we can conclude that the dominant conduction mechanism is ascribed toSchottky emission at high electric field (>1MV/cm) and hopping conduction at lowelectric field (<1MV/cm). According to our results, the oxide plasma surfacetreatmenton as-deposited $BaTa_2O_6$ resulted in lowering interfacebarrier height and thus, leakage current when a negative voltage applied to the A1 electrode. This can be explained by reduction of surface contamination via etching surface and filling defects such as oxygen vacancies.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.181-187
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• 1997

The layered BaTiO3 thin films with a high dielectric constant of polycrystalline BaTiO3 and a good in-sulating property of amorphous BaTiO3 were prepared. And their electrical properties were characterized with stacking methods. The BaTiO3 thin films were prepared by rf-magnetron sputtering technique using a ceramic target on Indium-doped Tin oxide coated glasses. A new stacking method resulted in higher dielec-tric constant, capacitance per unit area, and breakdown strength than those prepared by a conventional stacking method; the new method continuously decrease the substrate temperature after initial deposition of a polycrystalline BaTiO3 layer. The observed high dielectric constant could be explained only by a mul-tilayered amorphous/microcrystalline/polycrystalline structure, which was confirmed indirectly by AES depth profile.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1078-1086
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• 1996

The peroxo-polytungstic acid was formed by the direct reaction of tungsten powder with the hydrogen peroxide solution. Peroxo-polytungstic powder were prepared by rotary evaporator using the fabricated on to ITO coated glass as substrate by dip-coating method using $2g/10mL(W-IPA/H_2O)$ sol solution. A substrate was dipped into the sol solution and after a meniscus had settled, the substrate was withdrawn at a constant rate of the 3mm/sec. Thicker layer could be built up by repeated dipping/post-treatment 15 times cycles. The layers dried at the temperature of $65{\sim}70^{\circ}C$ during the withdrawn process, and then tungsten oxides thin film was formed by final heating treatment at the temperature of $230{\sim}240^{\circ}C$ for 30min. A linear rotation between the thickness of thin film and the number of dipping/post-treatment cycles for tungsten oxides thin films made by dip-coating was found. The thickness of thin film had $60{\AA}$ after one dipping. From the patterns of XRD, the structure of tungsten oxides thin film identified as amorphous one and from the photographs of SEM, the defects and the moderate cracks were observed on the tungsten oxides thin film, but the homogeneous surface of thin films were mostly appeared. The electrochemical characteristic of the $ITO/WO_3$ thin film electrode were confirmed by the cyclic voltammetry and the cathodic Tafel polaization method. The coloring bleaching processes were clearly repeated up to several hundreds cycles by multiple cyclic voltammetry, but the dissolved phenomenon of thin film revealed in $H_2SO_4$ solution was observed due to the decrease of the current densities. The diffusion coefficient was calculated from irreversible Randles-Sevick equation from the data obtained by the cyclic voltammetry with various scan rates.