• Electrical & Electronic Materials
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• v.9 no.2
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• pp.132-137
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• 1996

Pb(Zr$_{x}$Ti$_{1-x}$ )O$_{3}$ solutions prepared by sol-gel processing with different Zr/Ti ratio were coated on Pt/SiO$_{2}$/Si substrates using spin coating method. Coated films were annealed by rapid thermal annealing at 650.deg. C for 20sec to fabricate Pb(Zr, Ti)O$_{3}$ ferroelectric thin films. Electrical properties of the films such as dielectric constant and loss, ferroelectric hysteresis, fatigue, switching time, and leakage current were measured. Hysteresis of the films with different Zr/Ti ratio yield Pr ranging 10-21.mu.C/cm$^{2}$, E$_{c}$ ranging 37.5-137.5kV/cm. Hysteresis curve was changed from square-type to slim type according to increasing Zr contents. Switching time was faster than 180ns, and leakage current was about 20.mu.A/cm$^{2}$. The film underwent above 10$^{8}$ cycles of reversed polarization showed fatigue with increased coercive field and decreased remnant polarization.tion.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.5
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• pp.187-192
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• 2004

We try to use isopropanol which has low boiling point to prepare ZnO thin films at low temperature. ZnO thin films were prepared by sol-gel spin-coating method using zinc acetate dehydrate-isopropanol-monoethanolamine (MEA) solution. The c-axis preferred orientation and optical properties of ZnO films with preheating temperature have been investigated. ZnO thin films were preheated at 200 to $300^{\circ}C$ with an interval of $25^{\circ}C$ and post-heated at $650^{\circ}C$. The ZnO film preheated at $275^{\circ}C$ and post-heated at $650^{\circ}C$ was highly oriented along c-axis (002) plane, and the surface with homogeneous and dense microstructures was formed having nano-sized grains. The optical transmittance was above 90 % in the visible range and exhibited absorption edges at 368 nm wavelength.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1175-1178
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• 2005

Brittle materials, especially single-crystal silicon wafer, are widely used for sensors, IC industry, and MEMS applications. e general machining process of crack easy materials is by chemical agents, but it is hazardous and time consuming. Also, it is difficult to get high aspect ratio micro structure. As an alternative tool, an AJM(Abrasive jet machining) is promising method in terms of high aspect ratio and production cost. In this study, to get more precise detail compared to general AJM, photo polymer mask, SU-8, used in photolithography was applied in AJM. Process parameters such as abrasive diameter, air pressure, nozzle diameter, flow rate of abrasive in AJM and a variety of conditions in spin coating were decided. Finally, micro channel and mixer was fabricated to see the efficiency of the AJM with photo polymer mask.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.2
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• pp.139-145
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• 2015

In this paper, the flexible piezoelectric nanocomposite generator(NCG) device based on $BaTiO_3$ nanostructures was fabricated via simple and low-cost spin coating method. The $BaTiO_3$ nanostructures synthesized by self-assembly reaction showed dendrite morphologies. To produce the piezoelectric nanocomposite(p-NC layer) which acts as an electric energy source in NCG device, the piezoelectric nanopowders($BaTiO_3$) were dispersed in polydimethylsiloxane(PDMS). Sequently, the p-NC layer was inserted in two dielectric layer of PDMS; these layers enabled the NCG device flexibility as well as durability prohibiting detachment(exfoliation) for significantly mechanical bending motions. The fabricated NCG device shows average maximum open circuit voltage of 6.2 V and average maximum current signals of 300 nA at 20 wt% composition of $BaTiO_3$ nanostructures in p-NC layer. Finally, the flexible energy harvester generates stable output signals at any rate of frequency which were used to operate LCD device without any external energy supply.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.186.1-189
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• 2001

Ferroelectric $Bi_{4-x}$La$_{x}$Ti$_3$O$_{12}$ (BLT)thin films with various compositions(x=0.65, 0.70, 0.75) were prepared on Pt//Ti/SiO$_2$/Si(100) substrate by metal-organic deposition. The electrical and structural characteristics of BLT thin films were investigated to develop ferroelectric thin films for capacitor layers of FRAM. After spin coating, thin films were annealed at $650^{\circ}C$ for 1hour in oxygen atomosphere. Scanning electron micrographs showed uniform surfaces composed of rod-like grains. The $Bi_{4-x}$La$_{x}$Ti$_3$O$_{12}$ (x=0.70) thin film capacitors with a Pt top electrode showed better ferroelectric properties than other films. At the applied voltage of 5V, the dielectric constant($\varepsilon$$_{r}$), dissipation factor(tan$\delta$),remanent polarization(2Pr), and coercive field(2Ec) of the $Bi_{4-x}$La$_{x}$Ti$_3$O$_{12}$ (x=0.70)thin films were about 272.54, 0.059, 32.4 $\mu$C/cm$^2$, 2Ec=119.9kV/cm. Also the capacitor did not show any significant fatigue up to 4.8$\times$10$^{10}$ read/write switching cycles.hing cycles.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.861-864
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• 2002

Ferroelectric $Bi_{4-x}Nd_xTi_3O_{12}$(BNdT) thin films with the composition(x=0.75) were prepared on pt/Ti/$SiO_2$/Si(100) substrate by metal-organic deposition. The electrical and structural characteristics of BNdT thin films were investigated to develop ferroelectric thin films for capacitor layers of FRAM. After spin coating, thin films were annealed at $650^{\circ}C$ for 1hour in oxygen atmosphere. Scanning electron micrographs showed uniform surfaces composed of rod-like grains. The $Bi_{4-x}Nd_xTi_3O_{12}$(X=0.75) thin film capacitors with a Pt top electrode showed better ferroelectric properties. At the applied voltage of 5V, the dielectric constant$(\varepsilon_r)$, dissipation factor$(tan{\delta})$, remanent polarization(2Pr) and nonvolatile swiching charge of the $Bi_{4-x}Nd_xTi_3O_{12}$(x=0.75)thin films were about 346.7, 0.095, $56{\mu}C/cm^2$ and $38{\mu}C/cm^2$ respectively. Also the capacitor did not show any significant fatigue up to $8{\times}10^{10}$ read/write switching cycles at a frequency of 1MHz.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.834-836
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• 2008

We demonstrated micro-scale conducting polymer patterning based on a selective surface treatment. A substrate with a patterned photoresist was immersed into OTS (Octadecyltrichlosilnae) solution. The protected substrate areas were hydrophilic after removing the PR resist, where a conducting polymer solution was coated selectively by spin-coating method.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1638-1641
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• 2008

We have investigated the effectiveness of a gravure printing method for the fabrication of organic light-emitting diode (OLED) and Organic Thin Film Transistor (OTFT). Printing of the organic layers was performed with a small-scale gravure coating machine, while the metallic layers were vacuum-evaporated. Devices with gravure-printed layers are at least comparable with the spin-coated devices. Effects of the solvent formulation and surface energy mismatch between the organic layer materials on the printed patterns and device performance were discussed. We will present the initial design and experimental data of OTFT fabricated by roll-type soft contact transfer process.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.511-514
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• 2010

Perfluorinated polymer($Cytop^{TM}$) was deposited on selective area of AlGaN/GaN HEMT structure using low cost and simple spin-coating method, and the electrical characteristics of the device was analyzed for application of passivation layer on semiconductors. Gate lag measurement results of $Cytop^{TM}$ passivated and unpassivated HEMT were compared. Passivated device shows improved 65 % pulsed drain current of dc mode value. Rf measurements were also performed. $Cytop^{TM}$ passivated HEMT have similar rf performance to PECVD grown $Si_3N_4$ passivated device. $Cytop^{TM}$ passivation layer may play an important role in mitigating surface state trapping in the region between gate and drain.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.893-900
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• 1999

Silica films were prepared on Si single crystal substrates by sol-gel process using TEOS as starting materials. Films were fabricated by a spin coating technique. Sol solutions were prepared by varying the compositions of CH3OH, H2O and DMF with fixed molar ratio of TEOS=1, HCl=0.05(mol). Wetting behavior viscosity of solutions gelation time thickness of films and cracking behavior were investigated with the various solution compositions. Wetting behaviors of solutions depended on the solution compositions mixing method and mixing rate. The optimum composition of sol was TEOS : DMF ; CH3OH: H2O :HCl=1:2:4:4:0.05(mol) and the mixing rate of solution was optimized at 1 ml/min. Viscosity of solutions were controlled by choosing a reaction time(elapsed time after mixing) at a room temperature so that we could get up to 800nm thick film The surface roughness was getting poor when thickness of films was thicker than 500nm. Thickness of coated films were increased with decreasing amount of CH3OH. The best surface roughness was obtained at the content of CH3OH 4 mol. The shortest gelation time was obtained with the content of CH3OH 8 mol. Crack-free filkms were fabricated when sintered at 500$^{\circ}C$ for 1 hr with heating rate of 0.6$^{\circ}C$/min.