• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.25-28
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• 2000

In this paper, three types of organic electroluminescent devices(OELD) were fabricated on mechanically flexible plastic substrate by using vacuum deposition method. The devices consist of a hole transporting material such as TPD, a light-emitting material such as Alq$\sub$3/ and an electron transporting material, blocking material such as PBD. Electrical and optical properties of these OELDs were measured. This paper shows that organic small molecules based on OELD can be successfully deposited on a flexible plastic substrate. This points open the potential for low cost mass production of flexib]e displays, including roll to roll processing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.2
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• pp.97-103
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• 2014

Phase transition properties of the copolymer films of polyvinylidene fluoride (PVDF) and trifluoroethylene(TrFE), P(VDF-TrFE), were studied with X-ray diffraction (XRD) and polarization modulated ellipsometry (PME). XRD studies on both Langmuir-Blodgett (LB) films and spin coated films exhibit conversions from ferroelectric phase to paraelectric phase at $108{\pm}2^{\circ}C$ on heating and paraelectric phase to ferroelectric phase at $78{\pm}2^{\circ}C$ on cooling. The presence of the ferroelectric-paraelectric phase transition is also confirmed by the PME technique for the first time in this study. PME was proved to be a very sensitive tool in the measurement of the structural changes at the nano-thickness films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.42-46
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• 2000

${\beta}{\cdot}In_2S_3$ 및 ${\beta}{\cdot}In_2S_3:Co^{2+}$ 은 $In_2S_3$+S+ZnS를 출발물질로 하여 ($ZnCl_2+I_2$)를 수송매체로 사용한 chemical transport reaction method로 성장시켰다. 성장된 단결정은 tetragonal structure를 갖고 298K에서 indirect optical energy gap은 2.240eV, 1.814eV로 각각 주어졌고, direct optical energy gap은 2.639eV, 2.175eV로 각각 주어졌다. ${\beta}{\cdot}In_2S_3:Co^{2+}$ single crystal에서 impurity optical absorption peak가 나타났으며, 이들 peaks의 origin은 $Co^{2+}(Td)$ ion의 energy level 간의 electron transition임을 crystal field theory를 적용하여 규명하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.4
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• pp.272-279
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• 2003

In this work Zn$_4$GeSe$_{6}$ :CO$^{2+}$ single crystals were grown by the chemical transport reaction method in which the iodine was used as the transporting agent. The Zn$_4$GeSe$_{6}$ :CO$^{2+}$ single crystal was found to have a monoclinic structure. The optical absorption spectra of grown crystals were investigated using a temperature-controlled UV-VIS -NIR spectrophotometer. The temperature dependence of band-edge absorption was in a good agreement with the Varshni equation. The observed impurity absorption peaks could be explained as arising from the electron transition between energy levels of Co$^{2+}$ ion sited at the T$_{d}$ symmetry point.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.40-40
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• 2010

Structural, electrical, and optical properties of atomic layer-controlled AI-doped ZnO (ZnO:Al) films grown on glass by atomic layer deposition (ALD) were characterized with various $Al_2O_3$ film contents for use as transparent electrodes. Unlike films made using sputtering methods, the diffraction peak position of the films grown by ALD based on alternate self-limiting surface chemical reactions moved progressively to a wider angle (red shift) with increasing $Al_2O_3$ film content, which seems to be evidence of Zn substitution in the film by layer-by-layer growth. By adjusting the $Al_2O_3$ film content, the electrical resistivity of ZnO:Al film with the $Al_2O_3$ film content of 2.96% reached the lowest electrical resistivity of $9.80{\times}10^{-4}\Omega{\cdot}cm$, in which the carrier mobility, carrier concentration, and optical transmittance were $11.20\;cm^2V^{-1}s^{-1}$, $5.69{\times}10^{20}\;cm^{-3}$, and 94.23%, respectively. Moreover, the estimated figure of merit value for the transparent conductive oxide applications from our best sample was $7.7\;m{\Omega}^{-1}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.6
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• pp.471-478
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• 2002

Vacuum evaporated cadmium sulphide (CdS) thin films were implanted with $Ar^+$ and $N^+$ for different doses. The properties of the ion implanted CdS thin films have been analysed using XRD, optical transmittance spectra, and Raman scattering studies. Formation of Cd metallic clusters were observed in ion implanted films. The band gap of $Ar^+$ doped films decreased from 2.385 eV of the undoped film to 2.28 eV for the maximum doping. In the case of $N^+$ doped film the band gap decreased from 2.385 to 2.301 eV, whereas the absorption coefficient values increased with the increase of implantation dose. On implantation of both types of ions, the Raman peak position appeared at $299\textrm{cm}^{-1}$ and the FWHM changed with the ion dose.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.43-49
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• 2002

Gray-colored materials were synthesized from ball-milled ZnO powders under a thermal annealing at 1380$^{\circ}C$ with an argon carrier gas for 3 hours. The synthesized materials were identified to be wurtzitic hexagonal structured ZnO nanowires by X-ray diffraction and scanning electron microscopy. The ZnO nanowires have the long cylinder-like shape of which cross-section is a circle, and these nanowires are in the range 15∼40 nm width and 10-70 $\mu\textrm{m}$ length, respectively. Transmission electron microscopy revealed that these nanowires are single-crystalline and grow along [110] direction. The optical properties of the ZnO nanowires were investigated with photoluminescence. The analytic results revealed that ZnO nanowires have the singly ionized oxygen vacancies in the surface lattices, as they emit strong green light in room temperature PL. In addition, the growth mechanism of the ZnO nanowires can be described by the vapor-solid procedures.

• Journal of the Korean institute of surface engineering
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• v.38 no.3
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• pp.112-117
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• 2005

In this paper, CdS thin films, which were widely used as a window layer of the CdS/CdTe and the $CdS/CuInSe_2$heterojunction solar cell, were grown by chemical bath deposition, and the structural, optical and electrical properties of the films on reaction temperatures were investigated. Cadmium acetate and thiourea were used as cadmium and sulfur source, respectively. And Ammonium acetate was used as the buffer solution. As the reaction temperatures were increased, the deposition rate of CdS fllms prepared by CBD was increased and the grain size was large due to increasing reaction rate in solution, also optical transmittance of the films in visible lights was increased on rising reaction temperatures.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.362-364
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• 1993

The properties of near-field diffraction by small aperture are investagated and using of optical fiber taper as a small aperture are proposed. Near-field diffracted by aperture smaller than one wave length can overcome the resolution of conventional microscopy and optical component. In this paper production methods of sub-wave length optical fiber taper using solenoid are also proposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.9-14
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• 1996

The dependence of microstructural and optical properties of Ag-In-Sb-Te thin films on annealing heat-treatments was studied. It was found from the present work that the increase of reflectance after annealing heat-treatment is related with phase change of Ag-In-Sb-Te thin film from amorphous state to crystalline phases which involve Sb crystalline phase and AgInTe$_2$ stoichiometric phase. On the other hand, the reflectance is decreased after high temperature annealing (above 450$^{\circ}C$), due to the morphology .mange of film surface. For the purpose of practical application(erasable optical disk), we fabricated quadrilayered Ag-In-Sb-Te alloy disk, and annealed it with continuous laser beam. As result of this laser\ulcorner annealing treatment, we found that the increment of reflectance is 9.3% at 780nm wavelength. It might be considered that Ag-In-Sb-Te alloy optical disk is the big promising candidate for the erasable optical memory medium.