• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.223-228
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• 1998

Glass films of $SiO_2-TiO_2-M_xO_y$ (M = Co, Cr or Cu) have been prepared on soda-lime-silica slide glasses by the chemical solution method using a spin-coating technique. Commercially available tetraethyl orthosilicate, titanium trichloride, and cobalt-, chromium- and copper-nitrates were used as starting materials. No crystalline segregations of $Co_3O_4$, $Cr_2O_3$ and CuO were observed by X-ray diffraction ${\theta}-2{\theta}$ scans. From the optical transmission analysis, cobalt existed as $ Co^{2+}$ in tetrahedral coordination, chromium as $Cr^{6+}$ in tetrahedral symmetry and copper as $Cu^{2+}$ in octahedral coordination. Films with a crack-free and no texture exhibited homogeneous interfaces between the films and the substrates along the cross-section.

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.158-163
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• 2012

In this work, we have fabricated the $TiO_2$ thin films on Si and glass, polymer insulator substrates as the self-cleaning coating of polymer insulator. $TiO_2$ films were deposited by RF magnetron sputtering method with $TiO_2$ ceramic target and $TiO_2$ films of 100 nm thickness were fabricated with various RF powers. We have investigated the optical and surface, and structural properties of $TiO_2$ films prepared with various RF powers. As a result, the value of the contact angle of $TiO_2$ thin film is increased with increasing RF power and the value of the rms surface roughness is increased. The transmittance is decreased with increasing RF power. These results indicate that the variation of the surface and optical properties of $TiO_2$ thin films is related to the sputtering effects by increasing RF power.

• Journal of the Korean Applied Science and Technology
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• v.24 no.2
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• pp.149-159
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• 2007

In order to prepare high-solid coatings, acrylic resins, HSCs [poly (EA/EMA/2-HEMA/CLA)] that contain 90% solid, were synthesized by copolymerization of ethyl acrylate (EA), ethyl methacrylate (EMA), 2-hydroxyethyl methacrylate (2-HEMA) and caprolactone acrylate (CLA). The high-solid coatings named as CHSCs (HSCs/HDI-trimer) were prepared by the curing reaction between the acrylic resins containing 90% solid contents and the isocyanates (HDI-trimer) curing agent room temperature. The curing behavior and various properties were examined on the film coated with the both high-solid coatings. The glass transition temperatures $(T_g)$ of CHSCs increased proportionally with increasing the predicted $T_g$ value by Fox equation, and had nothing to do with the solid contents. The prepared film showed good properties for $60^{\circ}$ specular gloss, impact resistance, cross-hatch adhesion and heat resistance, and bad properties for pencil hardness, drying time, and pot-life. Among the film properties, the heat resistance was very excellent and could be explained by the introduction of functional monomers of CLA.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.191-196
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• 2010

Aluminum doped zinc oxide (AZO) films have been prepared on Coming 7059 glass substrates by r.f. magnetron sputtering method. A powder target instead of a conventional sintered ceramic target was used in order to improve the utilization efficiency of the target and reduce the cost of the film deposition process. The influence of sputter pressure on the structural, electrical, and optical properties of AZO films were studied. The AZO films had hexagonal wurtzite structure with a preferred c-axis orientation, regardless of sputter pressure and target types. The crystallinity and degree of orientation was increased by increasing the sputter pressure. For higher sputtering pressures, a reduction of the resistivity was observed due to a increase on the mobility and the carrier concentration. The lowest resistivity of $6.5{\times}10^{-3}\;{\Omega}-cm$ and the average transmittance of 80% can be obtained for films deposited at 15 mTorr.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.208-208
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• 2010

Indium zinc tin oxide (IZTO) thin films were studied as a possible alternative to indium tin oxide (ITO) films for providing low-cost transparent conducting oxide (TCO) for thin film photovoltaic devices. IZTO films were deposited onto glass substrates at room temperature. A dc/rf magnetron co-sputtering system equipped with a ceramic target of the same composition was used to deposit TCO films. Earlier studies showed that the resistivity value of $In_{0.6}Zn_{0.2}Sn_{0.2}O_{1.5}$ (IZTO20) films could be lowered to approximately $6{\times}10^{-4}ohm{\cdot}cm$ without sacrificing optical transparency and still maintaining amorphous structure through the optimization of process variables. The growth rate was kept at about 8 nm/min while the oxygen-to-argon pressure ratio varied from 0% to 7.5%. As-deposited films were always amorphous and showed strong oxygen pressure dependence of electrical resistivity and electron concentration values. Influence of forming gas anneal (FGA) at medium temperatures was also studied and proven effective in improving electrical properties. In this study, the chemical composition of the targets and the films varied around the $In_{0.6}Zn_{0.2}Sn_{0.2}O_{1.5}$ (IZTO20). It was the main objective of this paper to investigate how off-stoichiometry affected TCO characteristics including electrical resistivity and optical transmission. In addition to the composition effect, we have also studied how film properties changed with processing variables. IZTO thin films have shown their potential as a possible alternative to ITO thin films, in such way that they could be adopted in some applications where currently ITO and IZO thin films are being used. Our experimental results are compared to those obtained for commercial ITO thin films from solar cell application view point.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.359-363
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• 2005

The organic insulation devices with MIM (metal-insulator-metal) structures as PVP gate insulation films were prepared for the application of organic thin film transistors (OTFT). The co-polymer organic insulation films were synthesized by using PVP(poly-4-vinylphenol) as solute and PGMEA (propylene glycol monomethyl ether acetate) as solvent. The cross-linked PVP insulation films were also prepared by addition of poly (melamine-co-formaldehyde) as thermal hardener. The leakage current of the cross-linked PVP films was found to be about 300 pA with low current noise. and showed better property in electrical properties as compared with the co-polymer PVP insulation films. In addition, cross-linked PVP insulation films showed better surface morphology (roughness), showing about 0.11${\~}$0.18 nF in capacitance for all PVP film samples.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.167-167
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• 2010

Indium tin oxide (ITO) has been widely used as transparent conductive oxides (TCOs) for transparent electrodes of various optoelectronic devices, such as liquid crystal displays (LCD) and organic light emitting diodes (OLED). However, indium has become increasingly expensive and rare because of its limited resources. In addition, ITO thin films have some problems for OLED and flexible displays, such as imperfect work function, chemical instability, and high deposition temperature. Therefore, multi-component TCO materials have been reported as anode materials. Among the various materials, IZTO thin films have been gained much attention as anode materials due to their high work function, good conductivity, high transparency and low deposition temperature. IZTO thin films with a thickness of 200nm were deposited on Corning glass substrate at different substrate temperature by pulsed DC magnetron sputtering with a sintered ceramic target of IZTO (In2O3 70 wt%, ZnO 15 wt%, SnO2 15 wt%). We investigated the electrical, optical, structural properties of IZTO thin films. As the substrate temperature is increased, the electrical properties of IZTO are improved. All IZTO thin films have good optical properties, which showed an average of transmittance over 80%. These IZTO thin films were used to fabricate organic light emitting diodes (OLEDs) as anode and the device performances studied. As a result, IZTO has utility value of TCO electrode although it reduced indium and we expect it is possible for the IZTO to apply to flexible display due to the low processing temperature.

• Korean Journal of Materials Research
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• v.23 no.5
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• pp.271-275
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• 2013

Cobalt (Co) compounds have been used for centuries to impart rich blue color to glass, glazes and ceramics. Cobalt monoxide (CoO), an oxide of Co, is an inorganic compound that has long been used as a coloring agent in the ceramic industry. Unlike other coloring agents, CoO can be used to develop colors other than blue, and several factors such as its concentration in the glaze and firing condition have been suggested as possible mechanisms. For example, CoO produces a typical blue color called "cobalt blue" at very low concentrations such as 1 wt% in both oxidation and reduction firing conditions; a higher concentration of CoO (5 wt%) develops a darker blue color under the same firing conditions. Interestingly, CoO also develops a purple color at high concentrations above 10 wt%. In this study, we examined the applicability and mechanism of a novel purple glaze containing cobalt(II, III) oxide, one of the well characterized cobalt oxides. Experimental results show that an Augite crystal isoform (Augite-Fe/Co) in which Fe was replaced with Co is the main component contributing to the formation of the purple color. Based on these results, we developed a glaze using chemically synthesized Augite-Fe/Co crystal as a color pigment. Purple color glaze was successfully developed by the addition of 6~15 wt% of $Co_3O_4$ to magnesia lime.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.207-207
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• 2011

Amorphous transparent oxide semiconductors (a-TOS) have been widely studied for many optoelectronic devices such as AM-OLED (active-matrix organic light emitting diodes). Recently, Nomura et al. demonstrated high performance amorphous IGZO (In-Ga-Zn-O) TFTs.1 Despite the amorphous structure, due to the conduction band minimum (CBM) that made of spherically extended s-orbitals of the constituent metals, an a-IGZO TFT shows high mobility.2,3 But IGZO films contain high cost rare metals. Therefore, we need to investigate the alternatives. Because Aluminum has a high bond enthalpy with oxygen atom and Alumina has a high lattice energy, we try to replace Gallium with Aluminum that is high reserve low cost material. In this study, we focused on the electrical properties of IZO:Al thin films as a channel layer of TFTs. IZO:Al were deposited on unheated non-alkali glass substrates (5 cm ${\times}$ 5 cm) by magnetron co-sputtering system with two cathodes equipped with IZO target and Al target, respectively. The sintered ceramic IZO disc (3 inch ${\phi}$, 5 mm t) and metal Al target (3 inch ${\phi}$, 5 mm t) are used for deposition. The O2 gas was used as the reactive gas to control carrier concentration and mobility. Deposition was carried out under various sputtering conditions to investigate the effect of sputtering process on the characteristics of IZO:Al thin films. Correlation between sputtering factors and electronic properties of the film will be discussed in detail.

• Korean Journal of Materials Research
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• v.10 no.6
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• pp.430-436
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• 2000

In this paper, we have studied the effect of constituent ratio NiO, CuO and doped with B-Bi-Zn on proper-ties(microstructure, density, shrinkage, permeability as a function of frequency, etc.) of hexagonal-ferrite for high fre- quency chip-inductor material about several GHz. The permeability were analyzed by impedance analyzer(100 kHz∼ 40 MHz) and network analyzed(30 MHz∼3 GHz). As a result of the characteristics. the B-Bi-Zn glass ceramic was used to lower the sintering temperature for additive as function of frequency from 100kHz to 1.8 GHz showed con-stant tends. The maximum imaginary value of complex permeability was observed near the resonance frequency of 2 GHz.