• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.935-942
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• 2002

Gallium-doped ZnO (GZO) films were deposited on soda-lime glass substrate without heating using Ne, Ar, or Kr gas. Electrical properties of GZO films deposited at various total gas pressures were investigated for the film positions corresponding to the erosion region (region B) and outside the erosion region (region A) of the target. Region B showed high resistivity, which was attributed to the decrease in carrier density and Hall mobility, compared to region A. GZO films deposited using Ne gas showed the degradation in resistivity and crystallinity, whereas, GZO films deposited using Kr gas showed the improvement in resistivity and crystallinity. This degradation in film properties could be attributed to the film damage caused by the bombardment of high-energy particles. Especially, the energies of recoiled neutral atoms ($Ne^0,\;Ar^0,\;Kr^0$) calculated by Monte Carlo simulation corresponded to experimental results.

• Korean Journal of Materials Research
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• v.21 no.5
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• pp.277-282
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• 2011

Negative temperature coefficient (NTC) materials have been widely studied for industrial applications, such as sensors and temperature compensation devices. NTC thermistor thick films of $Ni_{1+x}Mn_{2-x}O_{4+{\delta}}$ (x = 0.05, 0, -0.05) were fabricated on a glass substrate using the aerosol deposition method at room temperature. Resistance verse temperature (R-T) characteristics of the as-deposited films showed that the B constant ranged from 3900 to 4200 K between $25^{\circ}C$ and $85^{\circ}C$ without heat treatment. When the film was annealed at $600^{\circ}C$ 1h, the resistivity of the film gradually decreased due to crystallization and grain growth. The resistivity and the activation energy of films annealed at $600^{\circ}C$ for 1 h were 5.203, 5.95, and 4.772 $K{\Omega}{\cdot}cm$ and 351, 326, and 299 meV for $Ni_{0.95}Mn_{2.05}O_{4+{\delta}}$, $NiMn_2O_4$, and $Ni_{1.05}Mn_{1.95}O_{4+{\delta}}$, respectively. The annealing process induced insulating $Mn_2O_3$ in the Ni deficient $Ni_{0.95}Mn_{2.05}O_{4+{\delta}}$ composition resulting in large resistivity and activation energy. Meanwhile, excess Ni in $Ni_{1.05}Mn_{1.95}O_{4+{\delta}}$ suppressed the abnormal grain growth and changed $Mn^{3+}$ to $Mn^{4+}$, giving lower resistivity and activation energy.

• Polymer(Korea)
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• v.29 no.2
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• pp.146-150
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• 2005

A nano-stereolithouaphy (NSL) apparatus has been developed for fabrication of microstructures with the resolution of 150 nanometers. In the NSL process, a complicated 3D structure can be fabricated by building layer by layer, so it does not require any sacrificial layer or any supporting structure. A laminated layer was fabricated by means of solidifying liquid-state monomers using two-photon absorption (TPA) which was induced by a femtosecond laser. When the fabrication of a 3D laminated structure was finished, unsolidified liquid-stage resins were removed to develop the fabricated structure by dropping several droplets of solvent, then the polymerized structure was only left on the glass substrate. A microstructure is fabricated by vector scanning method to save the fabrication time. The shell thickness of a structure is very thin within 200 nm, when it is fabricated by a single contour scanning (SCS) path. So, a fabricated structure can be deformed easily in the developing process. In this work, a double contour scanning (DCS) method was proposed to reinforce the strength of a shell typed structure, and a microcup was fabricated to show the usefulness of the developed NSL system and the DCS method.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.3
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• pp.193-203
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• 2005

Highly c-axis oriented nanocrystalline ZnO thin films on silica glass substrates were prepared by spin coating-pyrolysis process with a zinc naphthenate precursor. Only the XRD intensity peak of (002) phase was observed for all samples. With an increase in heat treatment temperature, the peak intensity of (002) phase increases. No significant aggregation of particle was present. From scanning probe microscopy analyses, three-dimensional grain growth, which was thought to be due to inhomogeneous substrate surface and c-axis oriented grain growth of the ZnO phase, was independent on heal-treatment temperature. Highly homogeneous surface of the highly-oriented ZnO film was observed at $800^{\circ}C$. All the films exhibited a high transmittance (above 80%) in visible region except film heat treated at $1000^{\circ}C$, and showed a sharp fundamental absorption edge at about $0.38{\sim}0.40{\mu}m$. The estimated energy band gap for all the films were within the range previously reported for films and single crystal. ZnO films, consisting of densely packed grains with smooth surface morphology were obtained by heat treatment at $600^{\circ}C{\sim}800^{\circ}C$, expected to be ideal for practical application, such as transparent conductive film and optical device.

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.453-457
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• 2007

Zinc oxide (ZnO) and Ga doped zinc oxide (GZO) with different thickness in range of 10nm to 100nm are prepared on glass substrate by RF magnetron sputtering at room temperature. The structural and optical properties of the thin films is evaluated. The structural properties of ZnO and GZO are investigated by Tunneling Electron Microscopy (TEM) and scanning electron microscopy (SEM). Optical properties are also investigated by UV-VIS-NIR spectrophotometer (200$\sim$1400nm). The much larger grain size of ZnO compared to GZO decreased the light scattering at the grain boundary and improved the transmittance. The transmittance of ZnO is higher than that of GZO through all of the ranges of wavelengths. In case of over 50nm, we found that the transmittance of ZnO is 20% higher than that of GZO.

• Journal of Microbiology and Biotechnology
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• v.11 no.3
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• pp.435-442
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• 2001

Poly(3-hydroxy-5-phenylvalerate) [P(3HPV)] was efficiently accumulated from 5-phenylvalerate (5PV) in Pseudomonas putida BM01 in a mineral salts medium containing butyric acid (BA) as the cosubstrate. A nove aromatic copolyester, poly(5 mol% 3-hydroxy-4-phenylbutyrate-co- 95 mol% 3-hydroxy-6-phenylhexanoate) [P(3HPB-co-3HPC)] was also synthesized from 6-phenylhexanoate (6PC) plus Ba. The two aromatic polymers, P(3HPV) and P(3HPB-co-3HPC), were found to be amorphous and showed different glass-transition temperatures at $15^{\circ}C$ and $10^{\circ}C$, respectively. When the bacterium was grown ina medium containing 20 mM 5PV as the sole carbon source for 140 h, 0.4 g/l of dry cells was obtained in a flask cultivation and 20 wt% of P(3HPV) homopolymer was accumulated in the cells. However, when it was grown with a mixture of 2 mM 5PV and 50 mM BA for 40 h, the yield of dry biomass was increased up to 2.5 g/l and the content of P(3HPV) in the dry cells was optimally 56 wt%. This efficient production of P(3HPV) homopolymer from the mixed substrate was feasible because BA only supported cell growth and did not induce any aliphatic PHA accumulation. The metabolites released into the PHA synthesis medium were analyzed using GC or GC/MS. Two $\beta$-oxidation derivatives, 3-phenylpropionic acid and trans-cinnamic acid, were found in the 5V-grown cell medium and these comprised 55-88 mol% of the 5PV consumed. In the 6PC-grown medium containing Ba, seven ${\beta}$-oxidation and related intermediates were found, which included phenylacetic acid, 4-phenylbutyric acid, cis-4-phenyl-2-butenoic acid, trans-4-phenyl-3-butenoic acid, trans-4-phenyl-2-butenoic acid, 3-hydroxy-4-phenylbutyric acid, and 3-hydroxy-6-phenylhexanoic acid. Accordingly, based on the metabolite analysis, PHA synthesis pathways from the two aromatic carbon sources are suggested.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.27-30
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• 2008

Purpose: This research is that $V_2O_5$ cathode's composition is possible in low temperature. Methods: Transparent in visible spectra range and crystallographically amorphous $V_2O_5$ thin films were prepared by simple vacuum thermal evaporation on soda-lime-silica slide glass substrate. After annealing at 100$^{\circ}C$, 150$^{\circ}C$ and 200$^{\circ}C$ for 10 minutes in air, the surface morphology and the fracture-cross section of the films were investigated by field emission - scanning electron microscope. Transmittance in visible spectra range and surface roughness of the films were analyzed by ultra violet - visible spectrophotometer and scanning probe microscope, respectively. Results: As the increase of annealing temperature from 100$^{\circ}C$ to 150$^{\circ}C$ and 200$^{\circ}C$, transmittance of the $V_2O_5$ films decreased. Optical properties will be fully discussed on the basis of the surface morphological results. Conclusions: Optical transmissivity was superior in case of 100$^{\circ}C$, and could make amorphous $V_2O_5$ thin film that surface quality of thin film did homogeneity.

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.24-28
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• 2012

$In_2O_3$ films were deposited by RF magnetron sputtering on a glass substrate and then the effect of post deposition annealing in nitrogen atmosphere on the structural, optical and electrical properties of the films was investigated. After deposition, the annealing process was conducted for 30 minutes at 200 and $400^{\circ}C$. XRD pattern analysis showed that the as deposited films were amorphous. When the annealing temperature reached 200-$400^{\circ}C$, the intensities of the $In_2O_3$ (222) major peak increased and the full width at half maximum (FWHM) of the $In_2O_3$ (222) peak decreased due to the crystallization. The films annealed at $400^{\circ}C$ showed a grain size of 28 nm, which was larger than that of the as deposited amorphous films. The optical transmittance in the visible wavelength region also increased, while the electrical sheet resistance decreased. In this study, the films annealed at $400^{\circ}C$ showed the highest optical transmittance of 76% and also showed the lowest sheet resistance of $89{\Omega}/\Box$. The figure of merit reached a maximum of $7.2{\times}10^{-4}{\Omega}^{-1}$ for the films annealed at $400^{\circ}C$. The effect of the annealing on the work-function of $In_2O_3$ films was considered. The work-function obtained from annealed films at $400^{\circ}C$ was 7.0eV. Thus, the annealed $In_2O_3$ films are an alternative to ITO films for use as transparent anodes in OLEDs.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.374-379
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• 2006

In this study, carbon nanotubes (CNTs) were grown on glass substrates coated with Ni/Cr by an atmospheric pressure plasma enhanced chemical vapor deposition(AP-PECVD) and their structural and electrical characteristics were investigated as a possible application to the field emitter of field emission display (FED) devices. The substrate temperature ($400{\sim}500^{\circ}C$) were varied and the grown CNTs were multi wall CNTs (at $500^{\circ}C$, 15 - 20 layers of graphene sheets, distance of each layer : 0.3nm, inner diameter: 10 - 15nm, outer diameter: 30 - 40nm). The ratio of defective carbon peak to graphite carbon peak of the CNTs grown at $500^{\circ}C$ (C measured by fourier transform(FT)-Raman was 0.772 $I_D / I_G$ ratio. When field emission properties were measured, the turn-on field was $2.92V/{\mu}m$ and the emission field at $1mA/cm^2$ was $5.325V /{\mu}m$.

• Journal of the Korean Magnetics Society
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• v.10 no.3
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• pp.106-111
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• 2000

The magnetic thin films can be prepared without vacuum process and under the low temperature (<100 $^{\circ}C$) by ferrite plating. We have performed ferrite plating of M $n_{x}$Z $n_{0.22}$F $e_{2.78-x}$ $O_4$(x=0.00~0.08) films and N $i_{x}$Z $n_{0.22}$F $e_{*}$2.78-x/ $O_4$(x=0.00~0.15) films on cover glass at the substrate temperature 90 $^{\circ}C$. The crystal structure of the samples has been identified as a single phase of polycrystal spinel structure by x-ray diffraction technique. The lattice constant in the M $n_{x}$Z $n_{0.22}$F $e_{2.78-x}$ $O_4$films increases but in the N $i_{x}$Z $n_{0.22}$F $e_{*}$2.78-x/ $O_4$films decrease with the composition parameter, x. The saturation magnetization in the M $n_{x}$Z $n_{0.22}$F $e_{2.78-x}$ $O_4$films does not greatly change, in agreement with observations on bulk samples.k samples.k samples.