• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.39.2-39.2
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• 2011

With the steady increase in the demand for flexible devices, mainly in display panels, researchers have focused on finding a novel material that have excellent electrical properties even when it is bended or stretched, along with superior mechanical and thermal properties. Graphene, a single-layered two-dimensional carbon lattice, has recently attracted tremendous research interest in this respect. However, the limitations in the growing method of graphene, mainly chemical vapor deposition on transition metal catalysts, has posed severe problems in terms of device integration, due to the laborious transfer process that may damage and contaminate the graphene layer. In addition, to lower the overall cost, a fabrication technique that supports low temperature and low vacuum is required, which is the main reason why solution-based process for graphene layer deposition has become the hot issue. Nonetheless, a direct deposition method of large area, few-layered, and uniform graphene layers has not been reported yet, along with a convenient method of patterning them. Here, we report an evaporation-induced technique for directly depositing few layers of graphene nanosheets with excellent uniformity and thickness controllability on any substrate. The printed graphene nanosheets can be patterned into desired shapes and structures, which can be directly applicable as flexible and transparent electrode. To illustrate such potential, the transport properties and resistivity of the deposited graphene layers have been investigated according to their thickness. The induced internal flow of the graphene solution during tis evaporation allows uniform deposition with which its thickness, and thus resistivity can be tuned by controlling the composition ratio of the solute and solvent.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.79-88
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• 1999

In this paper, the electro-deposition method for the rehabilitation of cracked concrete, based on the electro-chemical technique, is presented. The main purpose of this paper is to apply this technique to reinforced concrete members on land. After cracking with a specified load(crack width 0.5mm), 10$\times$10$\times$20cm concrete specimens with embedded steel bars were immersed in several solutions, then a constant current density between the embedded steel in concrete and an electrode in the solution was applied for 4~20 weeks. The results indicate that electro-deposits formed in this process are able to close concrete cracks and to coat the concrete surface and that formation of these electro-deposits is confirmed to have an effect of protection against detrimental materials. Therefore, it is demonstrated that the electro-deposition method can be usefully applied for the rehabilitation technique of concrete.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.907-912
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• 2005

Micro-patterns of $Pb(Zr_{0.53}Ti_{0.47})O_3$, PZT, thin films with a MPB composition were deposited on $Pt/Ti/SiO_2/Si$ substrate from molecular-designed PZT precursor solution by using self-assembledmonolayer(SAM) as a template. This method includes deposition of SAM followed by the optical etching by exposing the SAM to the UV-light, leading to the patterned SAM as a selective deposition template. The pattern of SAM was formed by irradiating UV-light to the SAM on a substrate and/or patterned PZT thin film through a metal mask for the selective deposition of patterned PZT or lanthanum nickel oxide (LNO) precursor films from alkoxide-based precursor solutions. As a result, patterned ferroelectric PZT and PZT/LNO thin film capacitors with good electrical properties in micrometer size could be successfully deposited.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.318.1-318.1
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• 2013

Nowadays Cu2ZnSnS4 (CZTS) solar cell is attracting a lot of attention as a strong alternative to CIGS solar cell due to nontoxic and inexpensive constituent elements of CZTS. From various processes for the fabrication of CZTS solar cell, solution-based deposition of CZTS thin films is well-known non-vacuum process and many researchers are focusing on this method because of large-area deposition, high-throughput, and efficient material usage. Typically the solution-based process consists of two steps, coating of precursor solution and annealing of the precursor thin films. Unlike vacuum-based deposition, precursor solution contains unnecessary elements except Cu, Zn, Sn, and S in order to form high quality precursor thin films, and thus the precise control of precursor thin film preparation is essential for achieving high efficient CZTS solar cells. In this work, we have investigated the effect of preparation condition of CZTS precursor thin films on the performance of CZTS solar cells. The composition of CZTS precursor solution was controlled for obtaining optimized chemical composition of CZTS absorber layers for high-efficiency solar cells. Pre-annealing process of the CZTS precursor thin films was also investigated to confirm the effect of thermal treatment on chemical composition and carbon residues of CZTS absorber layers. The change of the morphology of CZTS precursor thin film by the preparation condition was also observed.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.159-159
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• 2011

Among the semiconductor ternary compounds in the I-III-$VI_2$ series, $CulnS_2$ ($CulnSe_2$) are one of the promising materials for photovoltaic applications because of the suitability of their electrical and optical properties. The $CuInS_2$ thin film is one of I-III-$VI_2$ type semiconductors, which crystallizes in the chalcopyrite structure. Its direct band gap of 1.5 eV, high absorption coefficient and environmental viewpoint that $CuInS_2$ does not contain any toxic constituents make it suitable for terrestrial photovoltaic applications. A variety of techniques have been applied to deposit $CuInS_2$ thin films, such as single/double source evaporation, coevaporation, rf sputtering, chemical vapor deposition and chemical spray pyrolysis. This is the first report that $CuInS_2$ thin films have been prepared by Aerosol Jet Deposition (AJD) technique which is a novel and attractive method because thin films with high deposition rate can be grown at very low cost. In this study, $CuInS_2$ thin films have been prepared by Aerosol Jet Deposition (AJD) method which employs a nozzle expansion. The mixed fluid is expanded through the nozzle into the chamber evacuated in a lower pressure to deposit $CuInS_2$ films on Mo coated glass substrate. In this AJD system, the characteristics of $CuInS_2$ films are dependent on various deposition parameters, such as compositional ratio of precursor solution, flow rate of carrier gas, stagnation pressure, substrate temperature, nozzle shape, nozzle size and chamber pressure, etc. In this report, $CuInS_2$ thin films are deposited using the deposition parameters such as the compositional ratio of the precursor solution and the substrate temperature. The deposited $CuInS_2$ thin films will be analyzed in terms of deposition rate, crystal structure, and optical properties.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.1
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• pp.42-46
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• 2006

This paper presents a method for deposition an individual carbon nanotube (CNT). The alignment of a single CNT is very useful to perform studies related to applications in FET (Field Emitted Transistor), SET (Single Electron Transistor) and to make chemical sensor as well as bio sensors. In this study, we developed the deposition method of a CNT individualized in a solution. Using the electrokinetic method, we found the optimum conditions to assemble the nanotube and discussed about plausible explanation for the assembling mechanism. These results will be available to use for making the CNT sensor device.

• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.77-81
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• 2000

Silica glass films to utilize optical waveguides was fabricated by Aerosol Flame Deposition(AFD) method. As the amount of B2O3 increased in the sol solution of (92-x)SiO2-xB2O3-8P2O5, the thermophoretic deposition rate onto Si substrate was markedly lowered due to vaporizing out of B2O3 and P2O5 during the vaporization and reaction of the aerosol in the flame. GeO2 was added to 62SiO2-30B2O3-8P2O5 in order to control easily the refractive index of glass films. As the amount of GeO2 increased from 2 to 12 wt%, its refractive index increased from 1.4633 up to 1.4716.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.414-418
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• 1999

Typical metal oxide thin films having optical and electrical properties are widely used as inorganic functional materials. Liquid phase deposition(LPD) method, a new low temperature process, has been developed for the several advantages of no vacuum system, low cost, high throughput, and low processing temperature(<$50^{\circ}C$). Silica powder was added to 40wt% hydrofluoro-silicic acid($H_2$SiF\ulcorner) to obtain an immersing solution of silica-saturated hydrofluorosilicic acid solution. Boric acid solution was continuously added in the range from 0 to 0.05M to prepare supersaturated hydrofluorosilicic acid solution. LPD $SiL_2$film was formed with the variation of added amount of $H_2$O. The SiO$_2$thin film could be prepared from hydrofluorosilicic acid by LPD method. The thickness of LPD $_SiO2$film was influenced by the boric acid concentration and added amount of $H_2$O. Silicon in thin film existed as SiF\ulcorner by Raman spectrum.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.123-126
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• 2003

The electrophoretic deposition method using the suspension solution with additives under the electric potential was applied for the fabrication of YBCO superconductor wire. This method was able to simplify the fabrication facilities, and produce an uniform and dense thick film. To improve the critical current density of deposited films, the additive PEGs(Poly Ethylene Glycole) with the molecular weight of 600, 1000 and 3400, were used as chemical binders for the suspension solution. The organic additive PEG showed better effects to the properties of YBCO superconductor wire. The PEG improved the adhesion between superconductor particles and suppressed the crack on the surface, which enhanced the surface uniformity and density of YBCO deposited film. It was found that acetone suspension solution showed better deposition properties than the others. The samples fabricated in the solution with the additive, 8 vol.% of 1% PEG(1000), showed the highest critical current density measured as $2300{\sim}2400\;Acm^2$ at 77 K, 0 T.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.81-84
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• 1999

For the research of the effects on suspension solution with YBCO and BSCCO for elcectrophoretic deposition to prepare superconducting thick-film wire, it was investigated that the preheating technique for the superconducting powders in vacuum system was used with various solvent solutions of acetone, ethanol, toluene and buthanol for electrophoresis. As a result it was useful to remove the influence of remaining and adsorbed solvent solution which was existed between and on the particle surfaces when the specimens of superconducting wire by electrophoresis were treated in vacuum of 10$\^$-3/ Torr and temperature around 200$^{\circ}C$ in bell-jar system. From the prepared superconducting wire samples, the critical current density, Jc was measured by 4-point prove method in liquid N$_2$ at the value of 10$\^$3/ to 10$\^$4/ A/$\textrm{cm}^2$, respectively, for the YBCO and BSCCO superconducting wires.