• Journal of Magnetics
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• v.14 no.1
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• pp.27-30
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• 2009

Various sintered magnets containing $28{\sim}31\;wt%$ Nd and $0{\sim}7\;wt%$ Dy were evaluated for coercivity and irreversible flux loss as a preliminary study to develop highly-coercive, high-temperature magnets that can be applied for driving motors in a hybrid vehicle. The sintered magnets were prepared in sequence of strip casting, HD treatment, jet milling, magnetic field pressing, sintering and post-annealing. Increasing Dy content and adjusting post-annealing temperature monotonically increased coercivity of magnets from about 14 kOe to 30 kOe. A magnet containing 28 wt% Nd and 7 wt% Dy exhibits a $(BH)_{max}$+$_i{H_c}$ value of almost 64. This is very close to what the automobile industry considers as the minimum value (65) for a hybrid vehicle system. Moreover, irreversible flux loss of the magnet was about 3% at $200^{\circ}C$, which is well less than the allowable limit (5%) to a driving motor in hybrid vehicles.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.123-123
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• 2008

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.86-87
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• 2009

High quality $CuInSe_2$ (CIS) were grown on GaAs substrate by using the hot wall epitaxy method. The behavior of point defects in the CIS layer investigated by using photoluminescence (PL) at 10 K. Point defects originating from $V_{Cu}$, $V_{Se}$, $Cu_{int}$, and $Se_{int}$ were classified as donor or acceptor types. These PL results also led us to confirm that the p-type CIS layer had obviously converted into n-type after the Cu atmosphere treatment. Finally, we found that the In in the CIS layer did not form the native defects, because In existed in the form of stable bonds in the CIS layer.

• Transactions on Electrical and Electronic Materials
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• v.1 no.1
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• pp.17-21
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• 2000

In order to investigate the dependence of a content in lead lanthanum titanate (PLT) films and heat treatment, sol-gel process has been used. Four types of PLT thin films with the chemical formula, Pb$\_$1-x/ La$\_$x/Ti$\_$1-x/4/O$_3$(X=18, 21, 24 and 28 mole %) have been fabricated on Pt/Ti/SiO$_2$/Si multi-layers and ITO/glass substrates, The post-annealing temperature in the range of 400~700 $\^{C}$ is applied for the formation of perovskite structure in PLT films. The structureal, electrical and optical properties of PLT film with the addition of La content are estimated. The films orientation and surface structure of films are studied by XRD (X-ray diffraction) and SEM(scanning electron microscopy). The P-E hysteresis loop become narrower with increasing La content. The average transmittance of the films is about 80%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.378-378
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• 2010

The ZnSe epilayers were grown on the GaAs substrate by hot wall epitaxy. After the ZnSe epilayers treated in the vacuum-, Zn-, and Se-atmosphere, respectively, the defects of the epilayer were investigated by means of the low, temperature photoluminescence measurement. The dominant peaks at 2.7988 eV and 2.7937 eV obtained from the PL spectrum of the as-grown ZnSe epilayer were found to be consistent with the upper and the lower polariton peak of the exciton, $I_2$ ($D^{\circ}$, X), bounded to the neutral donor associated with the Se-vacancy. This donor-impurity binding energy was calculated to be 25.3 meV. The exciton peak, $I_l^d$, at 2.7812 eV was confirmed to be bound to the neutral acceptor corresponded with the Zn-vacancy.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.54-57
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• 2004

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique using an Nd:YAG laser with a wavelength of 266 m. During deposition, the experiment of the deposition of ZnO thin films has been performed for substrate temperatures in the range of $400^{\circ}C$ and flow rate of 350 sccm, films have been annealed at various substrate temperatures after deposition. After post-annealing treatment in the oxygen ambient, the structural properties of ZnO thin films were characterized by diffraction (XRD), SEM and the optical of the ZnO were characterized by photoluminescence (PL).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.59-62
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• 1998

Thermal treatment dependences of MFS devices in $BaMgF_4$ on Si structures have been investigated. $BaMgF_4$ thin films have been directly deposited on the p-Si(100) wafers at a low temperature of $300^{\circ}$ in an ultra high vacuum(UHV) system. After in-situ post-deposition annealing was conducted for 20 s at $650^{\circ}$, bias and temperature were applied to $BaMgF_4/Si$ structures. Although X-ray diffraction analysis showed that the films were polycrystalline in nature before and after bias temperature, the C-V properties were some different between with and without bias-temperature treatment.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.3
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• pp.126-132
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• 2002

The origin of image-sticking in metal-insulator-metal type thin-film diode liquid crystal displays(TFD-LCDs) is the asymmetric current-voltage(I-V) characteristic of TFD element. We developed that TFD-LCDs have reduced-image-sticking. Tantalum pentoxide(Ta$_2$O$\sub$5/) is a candidate for use in metal-insulator-metal(MIM) capacitors in switching devices for active-matrix liquid crystal displays(AM-LCDs). High quality Ta$_2$O$\sub$5/ thin films have been obtained from anodizing method. We fabricated a TFD element using Ta$_2$O$\sub$5/ films which had perfect current-voltage symmetry characteristics. We applied novel process technologies which were postannealed whole TFD element instead of conventional annealing to the fabrication. One-Time Post-Annealing(OPTA) heat treatment process was introduced to reduce the asymmetry and shift of the I-V characteristics, respectively. OPTA means that the whole layers of lower metal, insulator, and upper metal are annealed at one time. Futhermore, in this paper, we discussed the effects of top-electrode metals and annealing conditions.

• Journal of the Korean Electrochemical Society
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• v.20 no.3
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• pp.55-59
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• 2017

In this study, thermoelectric characteristics of perovskite $La_{0.5}Ca_{0.5}MnO_3$ (LCMO) nanomaterials were investigated by theoretical simulation and experimental analysis. Thermoelectric power factors calculated by DFT simulation were gradually enhanced as increase in annealing temperature. Maximum power factor was obtained with high magnitude of $S^2{\sigma}=566{\mu}W/m{\cdot}K^2$ at 1100 K through a dominant improvement of Seebeck coefficient compared with electrical conductivity. Experimentally, the LCMO nanomaterials were hydrothermally synthesized and then treated by post thermal annealing with temperature variation. X-ray diffraction and SEM analysis illustrated that LCMO exhibited orthorhombic perovskite structures with small grain size of 16~19 nm over 873 K. The results directly confirmed that improvement of crystallinity and decrease of mean grain size given by post thermal annealing lead to enhancements of electrical conductivity and Seebeck coefficient, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.8
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• pp.486-490
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• 2014

$Al_2O_3$ films on silicon carbide were fabricated by Aerosol deposition with annealing temperature at $800^{\circ}C$ and $1,000^{\circ}C$. The effect of thermal treatment on physical properties of $Al_2O_3$ thin films has been investigated by XRD (X-ray diffraction), AFM (atomic force microscope), SEM (scanning electron microscope), and AES (auger electron spectroscopy). Also electrical properties have been investigated by Keithley 4,200 semiconductor parameter analyzer to explain the interface trapped charge density ($D_{it}$), flatband voltage ($V_{FB}$) and leakage current ($I_o$). $Al_2O_3$ films become crystallized with increasing temperature by calculating full width at half maximum (FWHM) of diffraction peaks, also surface morphology is observed by topography measurement in non-contact mode AFM. $D_{it}$ was $2.26{\times}10^{-12}eV^{-1}.cm^{-2}$ at $800^{\circ}C$ annealed sample, which is the lowest value in all samples. Also the sample annealed at $800^{\circ}C$ has the lowest leakage current of $4.89{\times}10^{-13}A$.