• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.3
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• pp.137-141
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• 2002

CdS and $CdS:Co^{2+}$ single crystals were grown by CTR method using iodine as transport material. The grown single crystals have defect chalcopyrite structure with direct band gap. The optical energy band gap was decreased according to add of Co-impurity. We can observed the Co-impurity optical absorption peaks assigned to the $Co^{2+}$ ion sited at the $T_d$ symmetry lattice and we consider that they were attributed to the electron transitions between energy levels of ions.

• Journal of Magnetics
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• v.12 no.3
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• pp.129-132
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• 2007

Bismuth-substituted yttrium iron garnet (Bi:YIG, $Bi_{0.5}Y_{2.5}Fe_5O_{12}$) films were deposited with aerosol deposition method and their magnetic and optical properties were investigated as a function of annealing temperature. Since the ceramic films deposited with aerosol deposition method have not a perfect crystal structure due to non-uniform internal stress occurred by mechanical collision during their deposition, the post annealing could be a key process to release its internal stress and to improve its micro structure for optimizing the magnetic and magneto-optic properties of films. The crystallinity of Bi: YIG film was improved with increase of annealing temperature, and the saturation magnetization increased up to 87 emu/cc at $800^{\circ}C$. The Faraday rotation increased up to $1.4deg/{\mu}m$ by annealing at $700^{\circ}C$ around the wavelength of $0.5{\mu}m$. The optical transmittance of the Bi:YIG film was also improved in visible region.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.2
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• pp.199-201
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• 2022

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.42-44
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• 2008

In this study, we report an electrical properties of green OLEO, using the changed thickness of Al Layer. We investigated the electrical properties of OLEOs by IVL and optical properties by EL spectrum. The fundamental structure of green OLEOs was ITO anode/TPD($400{\AA}$)/$Alq_3(600{\AA})$)/LiF($10{\AA}$)/Al($200{\sim}600{\AA}$) cathode. The threshold voltage was low value according to the more thin Al layer. The luminance was increased by decreased cathode layer. The threshold voltage was 12V and wavelength was 530nm at $200{\AA}$ cathode.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.290.1-290.1
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• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.6
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• pp.454-460
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• 2021

In this work, we synthesized alloy-core InZnP quantum dots, which are more efficient than single-core InP quantum dots, using a solution process method. The effect of synthesis conditions of alloy core on optical properties was investigated. We also investigated the conditions that make up the gradient shell to minimize defects caused by lattice mismatch between the InZnP core and ZnS is 7.7%. The stable synthesis temperature of the InZnP alloy core was 200℃. Quantum dots consisting of three layered ZnSe gradient shell and single layered ZnS exhibited the best optical property. The properties of quantum dots synthesized in 100 ml and in 2,000 ml flasks were almost equal.

• Journal of Sensor Science and Technology
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• v.6 no.2
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• pp.163-171
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• 1997

CdS thin films for window material of solar cell were prepared by close spaced vapor transport deposition system and annealed at different temperatures. The structural, electrical, and optical properties of as-deposited and annealed CdS films were investigated as functions of substrate and annealing temperatures. The CdS thin films were grown perpendicularly to the substrate along the (002)plane with hexagonal structure regardless of the preparation conditions The resistivity of the CdS film deposited was increased gradually from $60{\Omega}cm$ for $25^{\circ}C$ to $2{\times}10^{4}{\Omega}cm$ for $300^{\circ}C$. The optical transmittance at the substrate temperature of $25^{\circ}C$ was about 80% in the the visible spectrum. The resistivity increased monotonically, and the optical transmittance was decreased substantially with annealing temperature due to the increased defect density in the CdS film.

• Journal of the Semiconductor & Display Technology
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• v.6 no.3
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• pp.35-39
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• 2007

ITO(Indium Tin Oxide) is the most attractive TCO(Transparent Conducting Oxide) materials for LCD, PDP, OLEDs and solar cell, because of their high optical transparency and electrical conductivity. However due to the shortage of indium resource, hard processing at low temperature, and decrease of optical property during hydrogen plasma treatment, their applications to the display industries are limited. Thus, recently the Al-doped ZnO(AZO) has been studied to substitute ITO. In this study, we have investigated the effect of different substrate temperature(RT, $150^{\circ}C$, $225^{\circ}C$, $300^{\circ}C$) and working pressure(10 mTorr, 20 mTorr, 30 mTorr, 80 mTorr) on the characteristics of AZO(2 wt.% Al, 98 wt.% ZnO) films deposited by RF-magnetron sputtering. We have obtained AZO thin films deposited at low temperature and all the deposited AZO thin films are grown as colunmar. The average transmittance in the visible wavelength region is over 80% for all the films and transmittance improved with increasing substrate temperature. Electrical properties of the AZO films improved with increasing substrate temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.403-404
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• 2007

We prepared the Al doped ZnO (AZO) thin film on polyethersulfon (PES) without any substrate heating by Facing Targets Sputtering (FTS) system. ZnO doped the content of Al 2 wt% was used and the sputtering conditions were gas pressure 1mTorr and input power 100W. The electrical, structural and optical properties of AZO thin films were investigated. To investigate the as-deposited thin film properties, we employed four-point probe, UV/VIS spectrometer, X-ray diffractometer (XRD), scanning electron microscopy (SEM), Hall Effect measurement system and Atomic Force Microscope (AFM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.58-61
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• 2005

In an effort to improve the electrical properties of ZnO:Al transparent electrode films, post-annealing treatment in hydrogen atmosphere was attempted with varying annealing time at 573 K for compatibility with typical display device fabrication processes. It was observed that carrier concentrations and mobilities increased with longer annealing time with small changes in crystallinity. This resulted in substantial decrease in resistivity from $4.80{\times}10^{-3}$ to $8.30{\times}10^{-4}{\Omega}cm$ due to increased carrier concentration. Such improvements in electrical properties are attributed to the passivation of the grain boundary surfaces. The optical properties of the films, which changed in accordance with the Burstein-Moss effect, were consistent with the observed changes in electrical properties.