• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.68-68
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• 2001

Thin films of polycrystalline silicon (poly-Si) is a promising material for use in large-area electronic devices. Especially, the poly-Si can be used in high resolution and integrated active-matrix liquid-crystal displays (AMLCDs) and active matrix organic light-emitting diodes (AMOLEDs) because of its high mobility compared to hydrogenated _amorphous silicon (a-Si:H). A number of techniques have been proposed during the past several years to achieve poly-Si on large-area glass substrate. However, the conventional method for fabrication of poly-Si could not apply for glass instead of wafer or quartz substrate. Because the conventional method, low pressure chemical vapor deposition (LPCVD) has a high deposition temperature ($600^{\circ}C-1000^{\circ}C$) and solid phase crystallization (SPC) has a high annealing temperature ($600^{\circ}C-700^{\circ}C$). And also these are required time-consuming processes, which are too long to prevent the thermal damage of corning glass such as bending and fracture. The deposition of silicon thin films on low-cost foreign substrates has recently become a major objective in the search for processes having energy consumption and reaching a better cost evaluation. Hence, combining inexpensive deposition techniques with the growth of crystalline silicon seems to be a straightforward way of ensuring reduced production costs of large-area electronic devices. We have deposited crystalline poly-Si thin films on soda -lime glass and SiOz glass substrate as deposited by PVD at low substrate temperature using high power, magnetron sputtering method. The epitaxial orientation, microstructual characteristics and surface properties of the films were analyzed by TEM, XRD, and AFM. For the electrical characterization of these films, its properties were obtained from the Hall effect measurement by the Van der Pauw measurement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.582-587
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• 2023

The effects of the annealing temperature on the structural, morphological, and luminescent properties of SrWO₄:Sm³⁺ thin films grown on quartz substrates by radio-frequency magnetron sputtering were investigated. The thin films were annealed at various annealing temperatures for 20 min in a rapid thermal annealer after growing the thin films. The experimental results showed that the annealing temperature has a significant effect on the properties of the SrWO₄:Sm³⁺ thin films. The crystal structure of the as-grown SrWO₄:Sm³⁺ thin films was transformed from amorphous to crystalline after annealing at 800℃. The preferred orientation along (112) plane and a significant increase in average grain size by 820 nm were observed with increasing the annealing temperature. The average optical transmittance in the wavelength range of 500~1,100 nm was decreased from 72.0% at 800℃ to 44.2% at an annealing temperature of 1,000℃, where the highest value in the photoluminescence intensity was obtained. In addition to the red-shift of absorption edge, a higher annealing temperature caused the optical band gap energy of the SrWO₄:Sm³⁺ thin films to fall rapidly. These results suggest that the structural, morphological, and luminescent properties of SrWO₄:Sm³⁺ thin films can be controlled by varying annealing temperature.

• Microbiology and Biotechnology Letters
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• v.32 no.2
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• pp.110-116
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• 2004

The over-expression in E. coli of the pHLN1-SO(＋) and pHLN2-80(－) plasmids cloned an insecticidal crystal protein (ICP) gene (crylAal type) from Bacillus thuringiensis var. kurstaki HD 1 was investigated through in part, the deletion of -80 bp promoter and an alternative change of cloning vector system. Two recombinant plasmids were constructed in an attempt to analyze the over-expression of the ICP in relations to its gene structure possessing only -14 bp ［Shine-Dalgarno (SD) sequence of -80 bp promoter］. Also, anther two recombinant plasmids similarly cloned the icp gene in a different vector system. The amounts of ICP produced from the recombinants were measured by SDS-PAGE and confirmed by Western blot analysis. One clone, pHLRBS1-14 clone in which only the SD sequence in the inverted orientation icp gene appeared, was more evident than the pHLRBS2-14 clone in which only the -14 bp SD sequence of the right orientated icp gene was shown to exist. The pHLN2-80(－) clone produced more ICP proteins than the pHLRBS1-14 clone. In the two clones, pHLNUC1-80 right-oriented icp gene and the pHLNUC2-80 clone inverted-orientation icp gene in a new different vector, the pHLNUC2-80 produced more ICP proteins in E. coli system. These results indicate that the P/ac promoter, the inverted icp gene insertion and -80 bp promoter (-66 bp part of the icp gene promoters), were concerned with the expression of the icp gene in the recombinant plasmids. In addition, the expression mechanism might result from the disruption of the transcription-suppressing regions in the promoter regions.

• Economic and Environmental Geology
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• v.17 no.2
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• pp.115-139
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• 1984

The Cu-Pb-Zn-Ag hydrothermal vein-type deposits which comprise the Sambong mine occur within calc-alkaline volcanics of the Cretaceous Gyeongsang Basin. The ore mineralization took place through three distinct stages of quartz (I and II stages) and calcite veins (III stage) which fill the pre-existing fault breccia zones. These stages were separated in time by tectonic fracturing and brecciation events. The reflection variations of one mineral depending on mineralization sequence are considered to be resulted from variation in its chemical composition due to different physico-chemical conditions in the hydrothermal system. The reflection power of sphalerite increases with the content of Fe substituted for Zn. Reflectances of the sphalerite grain are lower on (111) than on (100) surface. The spectral profiles depend on the internal reflection color. Sphalerite, showing green, yellow and reddish brown internal reflection, have the highest reflection power at $544m{\mu}$ (green), $593m{\mu}$ (yellow) and $615m{\mu}$ (red) wavelength, respectively. Chalcopyrite is recognized as biaxial negative from the reflectivity data of randomly oriented grains measured at the most sensitivity at $544m{\mu}$. The microindentation hardness against the Fe content (wt. %) for the sphalerite increases to 8.05% Fe and then decreases toward 9.5% Fe content. Vickers hardness of the sphalerite is considerably higher on surface of (100) than on (111). The relationship between Vickers hardness and crystal orientation of the galena was determined to be $VHN_{(111)}$ > $VHN_{(210)}$ > $VHN_{(100)}$. The softer sulfides have the wider variation of the diagonal length in the indentation. Diagonal length in the indentation is pyrite

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.599-604
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• 1998

We have investigated Pt and $RuO_2$ as a bottom electrode for ferroelectric capacitor applications. The bottom electrodes were prepared by using an RF magnetron sputtering method. Some of the investigated parameters were a substrate temperature, gas flow rate, RF power for the film growth, and post annealing effect. The substrate temperature strongly influenced the surface morphology and resistivity of the bottom electrodes as well as the film crystallographic structure. XRD results on Pt films showed a mixed phase of (111) and (200) peak for the substrate temperature ranged from RT to $200^{\circ}C$, and a preferred (111) orientation for $300^{\circ}C$. From the XRD and AFM results, we recommend the substrate temperature of $300^{\circ}C$ and RF power 80W for the Pt bottom electrode growth. With the variation of an oxygen partial pressure from 0 to 50%, we learned that only Ru metal was grown with 0~5% of $O_2$ gas, mixed phase of Ru and $RuO_2$ for $O_ 2$ partial pressure between 10~40%, and a pure $RuO_2$ phase with $O_2$ partial pressure of 50%. This result indicates that a double layer of $RuO_2/Ru$ can be grown in a process with the modulation of gas flow rate. Double layer structure is expected to reduce the fatigue problem while keeping a low electrical resistivity. As post anneal temperature was increased from RT to $700^{\circ}C$, the resistivity of Pt and $RuO_2$ was decreased linearly. This paper presents the optimized process conditions of the bottom electrodes for memory device applications.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.75.2-75.2
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• 2010

We studied the fabrication of polycrystalline silicon (pc-Si) films as seed layers for application of pc-Si thin film solar cells, in which amorphous silicon (a-Si) films in a structure of glass/Al/$Al_2O_3$/a-Si are crystallized by the aluminum-induced layer exchange (ALILE) process. The properties of pc-Si films formed by the ALILE process are strongly determined by the oxide layer as well as the various process parameters like annealing temperature, time, etc. In this study, the effects of the oxide film thickness on the crystallization of a-Si in the ALILE process, where the thickness of $Al_2O_3$ layer was varied from 4 to 50 nm. For preparation of the experimental film structure, aluminum (~300 nm thickness) and a-Si (~300 nm thickness) layers were deposited using DC sputtering and PECVD method, respectively, and $Al_2O_3$ layer with the various thicknesses by RF sputtering. The crystallization of a-Si was then carried out by the thermal annealing process using a furnace with the in-situ microscope. The characteristics of the produced pc-Si films were analyzed by optical microscope (OM), scanning electron microscope (SEM), Raman spectrometer, and X-ray diffractometer (XRD). As results, the crystallinity was exponentially decayed with the increase of $Al_2O_3$ thickness and the grain size showed the similar tendency. The maximum pc-Si grain size fabricated by ALILE process was about $45{\mu}m$ at the $Al_2O_3$ layer thickness of 4 nm. The preferential crystal orientation was <111> and more dominant with the thinner $Al_2O_3$ layer. In summary, we obtained a pc-Si film not only with ${\sim}45{\mu}m$ grain size but also with the crystallinity of about 75% at 4 nm $Al_2O_3$ layer thickness by ALILE process with the structure of a glass/Al/$Al_2O_3$/a-Si.

• Korean Journal of Materials Research
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• v.9 no.1
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• pp.14-17
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• 1999

Tin oxide films as an anode layer for microbatteries were deposited by using rf magnetron sputtering. Characterization of the films was carried out in terms of working pressure in the range of 5~30 mtorr. Rf power and substrate temperature during deposition were fixed at 2.5W/$\textrm{cm}^2$ and A.T., respectively. The crystal orientation of $SnO_2$films was changed from (110) to (101) or (211) with the increasing working pressure. Refractive index and film density of the films also decreased with the increasing working pressure. The $SnO_2$ thin film formed under optimum conditions was found to have a reversible capacity of 446.9$\mu$Ah/$\textrm{cm}^2$-$\mu\textrm{m}$ and good reversibility when the working pressure was fixed at 10mtorr. As the working pressure decreased, film density increased. It was thought that the capacity of $SnO_2$films increased due to the increase in the amount of active materials which can react with Li electrochemically. Furthermore, cycle characteristics of the anode material was also influenced by film stress.

• Journal of the Korean Wood Science and Technology
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• v.29 no.1
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• pp.60-67
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• 2001

The microscopic characteristics and cellulose structures of primary and secondary tissues in Pinus densiflora S. et Z. were examined. Cells of primary tissue in cross section showed an irregular arrangement and round shape. Fiber lengths were 200 to $250{\mu}m$ in primary tissue, and 1,500 to $1,600{\mu}m$ in secondary tissue. Cell diameters in primary tissue were larger than those in secondary tissue; 40 to $50{\mu}m$ in former and 10 to $20{\mu}m$ in latter. Crystallite width and d-spacing of (200) in both tissues did not show any significant differences. However, crystallinity indices by Segal's method showed significant differences as 23% in primary tissue and 35% in secondary tissue. In the orientation of cellulose microfibril, primary tissues had a random pattern, whereas, secondary tissues presented an oriented pattern with 20 to 30 degree. The cellulose crystalline of primary tissue was easily transformed into cellulose II by mercerization, but that of secondary tissue hardly transformed. It is considered that the difference of crystal transformation in both tissues could be caused by the difference of lignification.

• Polymer(Korea)
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• v.34 no.1
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• pp.32-37
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• 2010

Photo-alignment property of groove patterned surface prepared from blend of poly (vinyl cinnamate) (PVCi) and oligomeric dicinnamate was investigated for the application for alignment layer of liquid crystal display. The study of the photoreaction kinetics using UV-vis spectrum with the irradiation time showed that the reaction rate of oligomeric cinnamate was enhanced compared to that of PVCi. Blend where PVCi was main component showed a slight improvement on the photoreaction rate. It was unable to obtain groove patterned surface only using oligomeric cinnamate itself owing to the high crystalline character. However, blending of PVCi made it possible to obtain clear surface pattern. Molecular orientation could be confirmed from the polar plot data. It can be suggested that blend of oligomeric cinnamate and polymeric cinnamate is promising material for the photoalignment layer.

• Journal of the Korean Vacuum Society
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• v.20 no.4
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• pp.300-306
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• 2011

We report the surface distribution of metal (Ag, Au) nanoparticles grown on polarity-patterned ferroelectric substrates by photochemical reaction. Single crystal periodically polarity-patterned $LiNbO_3$(PPLN) was used as a ferroelectric substrate. The nanoparticles were grown by ultra-violet (UV) light exposure of the PPLN in the aqueous solutions including metas. The surface distribution of the grown nanoparticles were measured by atomic force microscopy and identification of the orientation of the polarity of the ferroelectric surface was performed by piezoelectric force microscopy. The Ag- and Au-nanoparticles grown on +z polarity regions are larger and denser than that on -z polarity regions. In particlur, the largest and denser Ag-nanoparticles were grwon on the polarity boundary regions of the PPLN while Au-nanoparticles were not specifically grown on the boundary regions. Thus, we found that the size and position of metal nanoparticles grown on ferroelectric surfaces can be controlled by UV-exposure time and polarity pattern structures. Also, we discuss the difference of the surface distribution of the metal nano-particles depending on the polarity of the ferroelectric surfaces in terms of surface band structures, reduced work fucntion, and inhomogeneous electric field distribution.