• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.532-536
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• 2011

The silicon nitride films were prepared by chemical vapor deposition using inductively coupled plasma. During the deposition, the substrate was heated at $150^{\circ}C$ and power 1,000 W. To evolution low temperature manufacture, we have studied the role of source gases, $SiH_4$, $NH_3$, $N_2$, and $H_2$, to produce Si-N and N-H bond in a-SiNx:H film growth. $SiH_4$, $NH_3$, and $N_2$ flow rate fixed at 100, 10, and 10 sccm, $H_2$ flow rate varied from 0 to 10 sccm by small scale. To get the electrical characteristics, we makes MIM structure, and analysis surface bonding state. Experimental data show that Si-N and N-H bond is increased and hence electrical characteristics is showed 3 MV/cm breakdown-voltage, and leakage-current $10^{-7}\;A/cm^2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.12
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• pp.1135-1140
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• 2008

Bismuth-telluride based thin film materials are grown by Metal Organic Chemical Vapor Deposition(MOCVD). A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_2Te_3$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $4{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_2Te_3$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_2Te_3$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the sample was heated by heating block and the voltage output measured. As expected for a thermoelectric generator, the voltage decreases linearly, while the power output rises to a maximum. The highest estimated power of $1.3{\mu}W$ is obtained for the temperature difference of 45 K. we provide a promising procedure for fabricating thin film thermoelectric generators by using MOCVD grown thermoelectric materials which may have nanostructure with high thermoelectric properties.

• Journal of Sensor Science and Technology
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• v.15 no.5
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• pp.309-316
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• 2006

The $SnO_{2}$ thin film sensors were fabricated by a thermal oxidation method. $SnO_{2}$ thin film sensors were treated in $N_{2}$ atmosphere. The sensors with $O_{2}$ treatment after $N_{2}$ treatment showed 70 % sensitivity for 1 ppm $H_{2}S$ gas, which is higher than the sensors with only $O_{2}$ treatment. The Ni metal was evaporated on Sn thin film on the $Al_{2}O_{3}$ substrate. And the sensor was heated to grow the Sn nanowire in the tube furnace with $N_{2}$ atmosphere. Sn nanowire was thermally oxidized in $O_{2}$ environments. The sensitivity of $SnO_{2}$ nanowire sensor was measured at 500 ppb $H_{2}S$ gas. The selectivity of $SnO_{2}$ nanowire sensor compared with thin film and thick film $SnO_{2}$ was measured for $H_{2}S$, CO, and $NH_{3}$ in this study.

• Food Science and Preservation
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• v.12 no.5
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• pp.489-495
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• 2005

Polyphenol oxidase (PPO) from Burdock (Arctium lappa L.) was purified and characterized. Purification of polyphenol oxidase was achieved by ammonium sulfate precipitation, Phenyl-sepharose CL-4B hydrophobic chromatography and Sephadex G-100 gel filtration chromatography. The molecular mass of the purified PPO was estimated to be 30 kDa by SDS polyacrylamide gel electrophoresis. In a substrate specificity, maximum activity was achieved with chlorogenic acid, followed by catechol and catechin. Whereas, there was low activity with hydroquinic acid, resorcinol or tyrosine. The optimum pH and temperature for enzyme activity were 7.0 and 35$\circC$ with catechol, respectively. The enzyme was most stable at pH 7.0 while unstable at acidic and alkaline pH. The enzyme was stable when heated to 40$\circC$. But heating at 50$\circC$ for more than 30 min caused 50% loss of activity. Ascorbic acid, L-cystein and $Cu^{2+}$ inhibited the activity of pholyphenol oxidase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.425-425
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• 2008

Bismuth-antimony-telluride based thermoelectric thin film materials were prepared by metal organic vapor phase deposition using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_2Te_3$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $4{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_2Te_3$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_2Te_3$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the device was heated by heating block and the voltage output was measured. The highest estimated power of 1.3mW is obtained at the temperature difference of 45K. We provide a promising approach for fabricating thin film thermoelectric generators by using MOCVD grown thermoelectric materials which can employ nanostructures for high thermoelectric properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.316-316
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• 2008

Using an evaporation method, $SiO_2$ was deposited as a buffer layer between a flexible PET substrate and a ITO film deposited by DC magnetron sputtering and electro-optical properties were investigated with thickness variance of $SiO_2$ layers. After coating a $SiO_2$ layer and a ITO film, the ITO/$SiO_2$/PET was heated up to $200^{\circ}C$ and the resistivity and the transmittance were measured by hall effect measurement system and UV/VIS/NIR spectroscopy. As a result of depositing a $SiO_2$ buffer layer, the resistivity increased and the transmittance and adhesion property were enhanced than ITO films with no buffer layers and the resistivity was lowered as $SiO_2$ thickness increased from 50 $\AA$ to 100 $\AA$. It was found that the transmittance was independent of annealing temperature variance in $150^{\circ}C{\sim}200^{\circ}C$ and the resistivity decreased as the temperature increased and especially decreasing rate of the resistivity was higher as the buffer layer thickness was thinner. So under optimized depositing of $SiO_2$ buffer layers and post-annealing of ITO/$SiO_2$/PET, ITO films with enhanced adhesion, electro-optical properties can obtained.

• Journal of the Korean Chemical Society
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• v.45 no.4
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• pp.351-356
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• 2001

Planarization of the free-standing diamond film surface as smooth as possible could be obtained by using the hydrogen plasma etching with the diffusion of the carbon species into the metal alloy (Fe, Cr, Ni). For this process, we placed the free-standing diamond film between the metal alloy and the Mo substrate like a metal-diamond-molybdenum (MDM) sandwich. We set the sandwich-type MDM in a microwave-plasma-enhanced chemical vapor deposition (MPECVD) system. The sandwich-type MDM was heated over ca. 1000 $^{\circ}C$ by using the hydrogen plasma. We call this process as the hydrogen plasma etching with carbon diffusion process. After etching the free-standing diamond film surface, we investigated surface roughness, morphologies, and the incorporated impurities on the etched diamond film surface. Finally, we suggest that the hydrogen plasma etching with carbon diffusion process is an adequate etching technique for the fabrication of the diamond film surface applicable to electronic devices.

• Progress in Superconductivity
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• v.7 no.1
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• pp.92-96
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• 2005

YBCO thin films on metal substrates were prepared by the metal-organic deposition using trifluoroacetates (TFA-MOD). To compensate the loss of Ba element from the precursor films due to the reaction with $CeO_2$ cap layer, we have employed Ba-excessive precursor solutions of $YBa_{2+x}Cu_{3}O_{7-{\delta}}$ ($0{\le}x{\le}0.1$). The precursor solutions were dip-coated on the metal substrates with $CeO_2$ cap layer, initially heated up to $400^{\circ}C$, and finally fired at the various high temperatures for 2 h in a reduced oxygen atmosphere. With this approach, YBCO films possessing critical temperature over 85 K could be successfully prepared on the metal substrates. The highest $T_{c,zero}$ value of 86 K was obtained from the Ba-excessive YBCO film of x=0.005 in $YBa_{2+x}Cu_{3}O_{7-{\delta}}$ fired at $750^{\circ}C$ for 2 h. However, unexpected $T_c$ suppression even in Ba-excessive YBCO samples requires further identification.

• BMB Reports
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• v.44 no.12
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• pp.816-820
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• 2011

There is a broad range of different small heat shock proteins (sHSPs) that have diverse structural and functional characteristics. To better understand the functional role of mitochondrial sHSP, NtHSP24.6 was expressed in Escherichia coli with a hexahistidine tag and purified. The protein was analyzed by non-denaturing PAGE, chemical cross-linking and size exclusion chromatography and the $H_6NtHSP24.6$ protein was found to form a dimer in solution. The in vitro functional analysis of $H_6NtHSP24.6$ using firefly luciferase and citrate synthase demonstrated that this protein displays typical molecular chaperone activity. When cell lysates of E. coli were heated after the addition of $H_6NtHSP24.6$, a broad range of proteins from 10 to 160 kD in size remained in the soluble state. These results suggest that NtHSP24.6 forms a dimer and can function as a molecular chaperone to protect a diverse range of proteins from thermal aggregation.

• Korean Journal of Materials Research
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• v.5 no.8
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• pp.929-935
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• 1995

In order to develop COG (Chip On Glass) technology for LCD module interconnecting the driver IC to Al pad electrode on the glass substrate, Anisotropic Conductive Adhesive(ACA) process, the most promising one among COG technologies, was investigated. ACA process was carried out by two steps, dispensing of ACA resin in the bonding area and curing by W radiation. Load on the chip was ranged from 2.0 to 15kg and the chip was heated at about 12$0^{\circ}C$. In resin, the density of conductive particles coated with Au or Ni at the surface were 500, 1000, 2000 and 4000 particles/$\textrm{mm}^2$, and the diameter of particles were 5, 7 and 12${\mu}{\textrm}{m}$. As a result of the experiments, ACA process using ACA particle of diameter and density of 5${\mu}{\textrm}{m}$ and 4000 particles/$\textrm{mm}^2$ respectively shows optimum characteristic with the stabilzed bonding properties and contact resistance.