• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.1
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• pp.39-43
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• 2021

In the case of ZnO:Al thin films, it is the best material that can replace ITO that is mainly used as a transparent electrode in electronic devices such as solar cells and flat-panel displays. In this study, ZnO:Al films were fabricated by using the RF dual magnetron sputtering method at various substrate temperatures. As the substrate temperature increased, the crystallinity of the ZnO:Al thin films was improved, and the electrical conductivity and electrical properties of the thin film improved owing to the increase in grain size. In addition, the surface roughness of the ZnO:Al thin films increased due to changes in the surface and density of the thin films. Moreover, the substrate temperature increased the density of thin films and improved their transmittance. To be applied to solar cells and other several electronic devices in the future, the hardness and adhesion properties of the thin film improve as the substrate temperature increases.

• Journal of the Korean institute of surface engineering
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• v.38 no.5
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• pp.188-192
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• 2005

Indium zinc oxide (IZO) thin films were deposited on glass substrate by dc magnetron sputtering. The effects of oxygen flow rate and deposition temperature on electrical and optical properties of the films were investigated. With addition of small amount of oxygen gas, the characteristic properties of amorphous IZO films were improved and the specific resistivity was about $4.8{\times}10^{-4}\Omega{\cdot}cm$. Change of structural properties according to the deposition temperature was observed with XRD, SEM, and AFM. Films deposited above $300^{\circ}C$ were found to be polycrystalline. Surface roughness of the films was increased due to the formation of grains on the surface. Electrical conductivity became deteriorated for polycrystalline IZO films. Consequently, high quality IZO films could be prepared by do sputtering with $O_{2}/Ar{\simeq}0.03$ and deposition temperature in range of $150\~200^{\circ}C$; a specific resistivity of $3.4{\times}10^{-4}{\Omega}{\cdot}cm$, an optical transmission over $90\%$ at wavelength of 550 nm, and a rms value of surface roughness about $3{\AA}$.

• Korean Journal of Metals and Materials
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• v.48 no.6
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• pp.565-569
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• 2010

We report on the characteristics of indium-oxide-doped ZnO (IZO) ohmic contact to p-GaN. The IZO ohmic contact layer was deposited on p-GaN by a Roll-to-Roll (RTR) sputter method. IZO contact film with a thickness of 360, 230 and 100 nm yielded an ohmic contact resistance of $4.70{\times}10^{-4}$, $5.95{\times}10^{-2}$, $4.85{\times}10^{-1}\;{\Omega}cm^{2}$ on p-GaN when annealed at $600{^{\circ}C}$ for 1 min under a nitrogen ambient, respectively. While the transmittance of IZO film with a thickness of 360 nm slightly increased in the wavelength range of 380-800 nm after annealing, the transmittance rapidly increased up to 80% after annealing at $600{^{\circ}C}$ in the wavelength range of 380~430 nm because the crystallization of IZO film and created Ga vacancies near the p-GaN surface region were affected by the annealing. These results indicate that ohmic contact resistance and transmittance of the IZO films improved.

• Elastomers and Composites
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• v.38 no.3
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• pp.235-242
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• 2003

A vulcanization reaction characteristics of an isoprene rubber (IR)-modified natural rubber/carbon black (NR/CB) composite was studied using in-situ electrical property measuring technique. Since the electrical conductivity of the sample composite would be changed continuously during the vulcanization reaction by rearranging of the carbon black particles within the sample, volume resistivity (${\rho}$) might be obtained as a function or reaction time. A stabilization time ($t_i$), maximum reaction speed time ($t_p$), and volume resistivity at that time(${\rho}_p$) were defined from the data for the Arrhenius analysis. Volume resistivity ${\rho}$ showed a comparatively high value of ${\sim}10^8$ order before the reaction started, and dramatically decreased to be stabilized within $1{\sim}2$ minutes as soon as the reaction started. As the more time elapsed, thereafter, ${\rho}$ decreased monotonously to a certain constant value through a peak, ${\rho}_p$ at time $t_p$, which was considered as the maximum reaction rate. As a result, while $t_i$ values were comparatively constant as $1{\sim}2$ minutes, $t_p$ values showed to become shorter and shorter as the reaction temperature.

• Korean Journal of Materials Research
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• v.16 no.5
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• pp.312-317
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• 2006

Binary skutterudite $CoSb_3$ compounds were prepared by the encapsulated induction melting (EIM) process, and their thermoelectric, microstructural and mechanical properties were examined. Single-phase ${\delta}-CoSb_3$ was successfully produced by the EIM and subsequent heat treatment at 773 K-873 K for 24 hours in vacuum. Seebeck coefficient increased with increasing heat treatment temperature up to 673 K, showing the positive signs in the range of measuring temperature. However, the samples heat-treated at 773 K-873 K showed negative Seebeck coefficient from room temperature to 400 K, while it showed positive signs above 400 K. Electrical resistivity decreased with increasing temperature, showing typical semiconducting conductivity. Thermal conductivity decreased drastically with increasing heat-treatment temperature. This is closely related with the phase transition to ${\delta}-CoSb_3$.

• Economic and Environmental Geology
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• v.30 no.4
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• pp.371-377
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• 1997

This paper presents the geophysical applications to the environmenml problem in an abandoned mine area. We would like to focus our attention on the mapping of the soil contamination and the detection of the buried mine tailings. For mapping the soil contamination. measurements of both in-situ magnetic susceptibility (k) and terrain conductivity were carried out. In-situ magnetic susceptibilities of the contaminated soil due to the acid mine drainage show higher values than those of the uncontaminated area. However. those data do not show the correlation with the degree of the soil contamination observed on the surface. The least-squares fitted formula obtained with the measured insitu magnetic susceptibilities is $k=4.8207{\times}W^{0.6332}$, where W is the $Fe^{+2}$ weight percentage. This weight gives most effect to magnetic susceptibility of the soil. Lateral variations of the soil contamination in the shallow subsurface can be detected by the electrical conductivity distributions from EM induction survey. TDIP (Time Domain Induced Polarization) and EM induction surveys were conducted to detect the buried mine tailings. From the results of TDIP, the spatial zone, which shows high chargeability-low resistivity, is interpreted as the buried mine tailings. Therefore, it is concluded that it is possible to discriminate the spatial zone from the uncontaminated ground.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.296-302
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• 1994

Polycrystalline CuInSeS12T thin were prepared by depositing Cu/In layer, which was sequentially sputtered varying the Cu/(Cu+In) mole ratio, on glass substrate and selenizing with selenium metal vapor in a nitrogen atmosphere. Compositional and structural, characterization was carried out by X-ray diffraction (XRD), wavelength-dispersive spectroscopy(WDS), and scanning electron microscope(SEM). Electrical characterization was carried out by the measurements of Hall effect, electrical resistivity. Large indium loss occurs in early stage of the selenization process. The selenized films which had mole ratios larger than 0.28 have chalcopyrite CuInSeS12T phase and these that had less mole ratios have sphalerite phase. The selenized films containing CuS1xTSe phase have Cu-rich CuInSeS12T phase and these that did not contain CuS1xTSe have In-rich CuInSeS12T phase. By optimizing the sputtering conditions,it is possible to fabricate CuInSeS12T thin films which have little secondary phases and an appropriate hole concentration (10S015T ~ 10S016TcmS0-3T) for solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.4
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• pp.303-310
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• 2010

We fabricated $La_{0.6}Sr_{0.4}MnO_3$ thin films using radio frequency (RF) magnetron sputtering. They were grown on sapphire substrates with various deposition conditions. After the growth of the $La_{0.6}Sr_{0.4}MnO_3$ thin films, they were annealed at various temperatures to be crystallized. We successfully fabricated single phase $La_{0.6}Sr_{0.4}MnO_3$ thin films with high electrical conductivity. The room temperature resistivity was $1.5{\times}10^{-2}{\Omega}{\cdot}cm$. It can be considered that $La_{0.6}Sr_{0.4}MnO_3$ thin films are one of the feasible candidates for electrodes for integrated device applications.

• Journal of the Korean institute of surface engineering
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• v.45 no.1
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• pp.1-7
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• 2012

Multi-walled carbon nanotube (MWCNT) aluminum composite powders were deposited to form coatings using a high velocity oxygen fuel (HVOF) spraying process. High thermal energy and contact with atmospheric oxygen were supplied as the MWCNT aluminum composite particles were exposed to a gas flow field at high temperature (${\sim}3.0{\times}10^3$ K) during HVOF spraying. As a result, the particles underwent full or partial melting and rapid solidification due to the high thermal energy, and the exposure to oxygen induced the interfacial reaction of MWCNTs within the particle. The electrical and mechanical properties of MWCNT aluminum composite coatings were evaluated based on microstructure analysis. Electrical resistivity, elastic modulus, and micro-hardness, of the MWCNT aluminum composite coatings were higher than those of pure aluminum coating. The contribution of MWCNTs to the aluminum matrix can be attributed to their high electrical conductivity, dispersion hardening and anchoring effects. The relationship among the properties and the interaction of the MWCNTs with the aluminum matrix is discussed.

• Transactions on Electrical and Electronic Materials
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• v.13 no.3
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• pp.111-115
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• 2012

Spray pyrolysis method was applied for the preparation of indium oxide ($In_2O_3$) thin films, by varying the substrate temperature range from 400-$600^{\circ}C$. All the samples were characterized at room temperature by using X-Ray diffraction, Scanning electron microscopy, Atomic Force Microscopy, Hall Effect and UV-Visible spectrophotometry. The optimal substrate temperature required for obtaining films of high crystallographic quality was $575^{\circ}C$. By comparing optical transmittance and electrical conductivity it was observed that the best figure of merit for these films was achieved for the same temperature and electrical resistivity was in the order of ${\rho}=1.47{\times}10^{-1}[{\Omega}cm]$. Gas sensing measurements of the films in ethanol showed enhancement with surface roughness and sheet resistance.