• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.229-236
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• 1998

In this paper, thin films of Polyimide (PI) were fabricated by vapor deposition polymerization method (VDPM) of dry processes. The film's properties with curing temperature and electrical properties were studies. The synthesis of hexafluoroisopropyliden-2,2-bis[phthalic anhydride](6FDA) and 4, 4'-diamino diphenyl ether (DDE) was carried out by vapor deposition polymerization(VDP) with the same deposition rate. The evaporation temperature of 6FDA and DDE were $214^{\circ}C$ and $137^{\circ}C$, respectively, so as to preserve balance of stoichiometry. The polymic acid (PAA) made by VDPM were changed to PI by thermal curing. The uniformity and density of PI thin films were increased according to increasing curing temperature. The relative permittivity and dissipation loss factor were 3.7 and 0.008 at the frequency of 100Hz~200KHz, respectively, for the fabricated in the curing temperature of $300^{\circ}C$. Also, the resistivity was about 1.05$\times$$ 10^{15}$$\Omega$cm at $30^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.239-242
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• 1998

Ca $F_2$ films have superior gate insulator properties than conventional gate insulator such as $SiO_2$, Si $N_{x}$, $SiO_{x}$, and T $a_2$ $O_{5}$ to the side of lattice mismatch between Si substrate and interface trap charge density( $D_{it}$). Therefore, this material is enable to apply Thin Film Transistor(TFT) gate insulator. Most of gate oxide film have exhibited problems on high trap charge density, interface state in corporation with O-H bond created by mobile hydrogen and oxygen atom. This paper performed Ca $F_2$ property evaluation as MIM, MIS device fabrication. Ca $F_2$ films were deposited at the various substrate temperature using a thermal evaporation. Ca $F_2$ films was grown as polycrystalline film and showed grain size variation as a function of substrate temperature and RTA post-annealing treatment. C-V, I-V results exhibit almost low $D_{it}$(1.8$\times$10$^{11}$ $cm^{-1}$ /le $V^{-1}$ ) and higher $E_{br}$ (>0.87MV/cm) than reported that formerly. Structural analysis indicate that low $D_{it}$ and high $E_{br}$ were caused by low lattice mismatch(6%) and crystal growth direction. Ca $F_2$ as a gate insulator of TFT are presented in this paper paperaper

• Solar Energy
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• v.11 no.1
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• pp.41-49
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• 1991

In this study, the (P)SiC/(N)Si solar cell is fabricated by the vacuum evaporation method with the substrate temperature at about $200{\pm}5[5^{\circ}C]$ and its characteristics are investigated. The optimal thickness of $1.2[{\mu}m]$ of SiC film is derived from the relation between film thickness and conversion efficiency. The characteristics of solar cells are improved by the annealing. The optimum annealing temperature and duration are $420[^{\circ}C]$ and 12[min], respectively it is shown that the peak values of spectral response are shifted to the long wavelength region with increasing the annealing temperature. The X-ray diffraction patterns and the scanning electron micrographs show the grain grow thin SiC film as the annealing temperature and time is increased. The best conversion efficiency is 11.7[%] for a $2.5{\times}1[cm^2]$ cell.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.361-368
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• 2004

We separated the multilayer structure of CD-R(compact disk-recordable) and investigated optimal spot marking conditions and physical and chemical transitions in response to various laser beam energh levels. Spot marking(80 ${\mu}{\textrm}{m}$ spot size) was produced on the surface of each layer using a Q-switched Nd:YAG laser between 27 mJ and 373mJ. By investigating resulting pit formation with Optical Microscopy(OM) and Optical Coherence Tomography(OCT), we analyzed the formation process of spot marking in the multilayer structure of different chemical composition. The localized heating of the substrate in the multilayer thin film caused the short temporal thermal expansion, and absorbed optical energy between reflective and dye interfaces melted dye and increased the volume. During the cooling phase, formation of pit and surrounding rim can be explained by three distinct processes; effect of surface tension, evaporation by spontaneous temperature increase due to laser energy, and mass flow from the recoil pressure. Our results shows that the spot marking formation process in the multilayer thin film is closely related to the layers' physical, chemical, and optical properties, such as surface tension, melt viscosity, layer thickness, and chemical composition.

• Solar Energy
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• v.12 no.2
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• pp.62-78
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• 1992

The solar cells of $ITO_{(n)}/Si_{(p)}$, which are ITO thin films deposited and heated on Si wafer 190[$^{\circ}C$], were fabricated by two source vaccum deposition method, and their electrical properties were investigated. Its maximum output is obtained when the com- position of the thin film consist of indium oxide 91[mole %] and thin oxide 9[mole %]. The cell characteristics can be improved by annealing but are deteriorated at temperature above 600[$^{\circ}C$] for longer than 15[min]. Also, we investigated the spectral response with short circuit current of the cells and found that the increasing of the annealing caused the peak shifted to the long wavelength region. And by experiment of the X-ray diffraction, it is shown to grow the grains of the thin film with increasment of annealing temperature. The test results from the $ITO_{(n)}/Si_{(p)}$ solar cell are as follows. short circuit current : Isc= 31 $[mW/cm^2]$ open circuit voltage : Voc= 460[mV] fill factor : FF=0.71 conversion efficiency : ${\eta}$=11[%]. under the solar energy illumination of $100[mW/cm^2]$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1241-1245
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• 2004

Continuous physical vapor deposition (PVD) method is one of many processes to fabricate long length coated conductor which is required for successful large-scale application of superconducting power devices. Three film deposition systems (pulsed laser deposition, sputtering, and evaporation) equipped with reel-to-reel(R2R) metal tape moving apparatus were installed and used to deposit multi-layer oxide thin films. Both RABiTS and IBAD texture templates are used. IBAD template consists of CeO$_2$(PLD)/YSZ(IBAD) on stainless steel(SS) metal tape, and RABiTS template has the structure of CeO$_2$/YSZ/Y$_2$O$_3$ which was continuously deposited on Ni-alloy tape using R$_2$R evaporation and DC reactive sputtering in a deposition system designed to do both processes. 0.4 m-long coated conductor with Ic(77 K) of 34 A/cm was fabricated using RABiTS template. 0.5 m and 1.1 m-long coated conductor with Ic(77 K) of 41 A/cm and 26 A/cm were fabricated using IBAD template.

• Journal of the Korean Magnetics Society
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• v.9 no.4
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• pp.210-216
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• 1999

The objective of this paper is to investigate corrosion behaviors of CoCrTa/CrNi thin film and post heat-treatment effect. An electron beam evaporator was used for films deposition. After evaporation, post heat-treatment was carried out under $5.0{\times}10^3$ Torr vacuum condition. Annealing temperature and time were 400 $^{\circ}C$ and 30 min, respectively. To understand the effect of annealing on corrosion behavior of CoCrTa/CrNi, potentiodynamic polarization technique and accelerated corrosion chamber test were undertaken. Corrosion potential is higher for the annealed samples (CoCrTa 400$\AA$/CrNi 1000$\AA$) than for as-deposited one. This is attributed to an enrichment of Cr in the surface layer of the thinfilm resulting in a more corrosion resistant material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.245-245
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• 2009

l-D nanostructured materials have much more attention because of their outstanding properties and wide applicability in device fabrication. Copper oxide(CuO) has been realized as a p-type metal oxide semiconductor with narrow band gap of 1.2 -1.5eV. Copper oxide nanostructures can be synthesized by various growth method such as oxidation reaction, thermal evaporation thermal decomposition, sol-gel. and Mostly CuO nanowire prepared on the Cu substrate such as Copper foil, grid, plate. In this study, CuO NWs were grown by thermal oxidation (at various temperatures in air (1 atm)) of Cu metal deposited on CuO (20nm)/$SiO_2$(250nm)/Si. A 20nm-thick CuO layer was used as an adhesion layer between Cu metal and $SiO_2$

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1491-1492
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• 2011

In this study, we investigated about the effect of hole transport layer materials(${\alpha}$-NPD, TPD) depending on the electrical properties of organic light emitting diode. In deposition method, we used thermal evaporation and it was a method for performing thin film by attaching vaporizing a molecule to substrate in a high thermal and vaccum. We analyzed luminance, current density, external quantum efficiency and current efficiency in 40 [nm] as optimization thickness of ${\alpha}$-NPD and TPD. In result of experiment, maximum luminance of TPD had 1.1 times higher than ${\alpha}$-NPD, but ${\alpha}$-NPD had luminance, external quantum efficiency, and current efficiency higher than TPD in low operating voltage. Actually, ${\alpha}$-NPD had efficiency higher than TPD in low operating voltage.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.128-128
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• 2003

Electrochromism (EC) is defined as a phenomenon in which a change in color takes place in the presence of an applied voltage. Because of their low power consumption, high coloration efficiency, EC devices have a variety of potential applications in smart windows, mirror, and optical switching devices. An EC devices generally consist of a transparent conducting layer, electrochromic cathodic and anodic coloring materials and an ion conducting electrolyte. EC has been widely studied in transition metal oxides(e.g., WO$_3$, NiO, V$_2$O$\sub$5/) Among these materials, WO$_3$ is a most interesting material for cathodic coloration materials due to its lush coloration efficiency (CE), large dynamic range, cyclic reversibility, and low cost material. WO$_3$ films have been prepared by a variety of methods including vacuum evaporation, chemical vapor deposition, electrodeposition process, sol-gel synthesis, sputtering, and laser ablation. Sol-gel process is widely used for oxide film at low temperature in atmosphere and requires lower capital investment to deposit large area coating compared to vacuum deposition process.