• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1605-1608
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• 2004

Single phase $CuInS_2$ thin film with a highest diffraction peak (112) at a diffraction angle ($2{\theta}$) of 27.7$^{\circ}$ was well made by SEL method at annealing temperature of 250 $^{\circ}C$ and annealing hour of 60 min in vacuum of $10^{-3}$ Torr or in S ambience for an hour. And the peak of diffraction intensity at miller index (112) of $CuInS_2$ thin film annealed in S ambience was shown a little higher about 11 % than in only vacuum. Single phase $CuInS_2$ thin films were appeared from 0.85 to 1.26 of Cu/In composition ratio and sulfur composition ratios of $CuInS_2$ thin films fabricated in S ambience were all over 50 atom%. Also when Cu/In composition ratio was 1.03, $CuInS_2$ thin film with chalcopyrite structure had the highest XRD peak (112). And lattice constant a and grain size of the thin film in S ambience were appeared a little larger than those in only vacuum. The largest lattice constant of a and grain size of $CuInS_2$ thin film in S ambience was 5.63 ${\AA}$ and 1.2 ${\mu}$m respectively. And the films in S ambience were all p-conduction type with resistivities of around $10^{-1}{\Omega}cm$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.3
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• pp.250-260
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• 1995

In general, a sintered rod is used as a feed in the growth of crystals by the floating zone(FZ) method. The sintering condition of the feed rod affected the stability of molten zone because it influenced the interface shape between the feed and the melt during the crystal growth. In this study, rutile and ruby crystals were chosen as samples to analyze the effect of the microstructures of the feed rods. In sintering of the feed rod for the growth of rutile and ruby single crystals, the difference of grain size between the inner and the outer region of the feed rod increased with the sintering temperature and dwelling time. As a result, it altered melting behavior of the feed. The uniform grain size of the sintered rod was necessary for the optimum growing condition of crystals. The effect of pores in the feed rod was not a dominant factor to grow crystals by the FZ method, which was confirmed by growing crystals with nonsinterd rods as feeds.

• Analytical Science and Technology
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• v.5 no.1
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• pp.115-120
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• 1992

The upper limit of solid solution of $Al_2O_3$ in $LiTaO_3$ was investigated using X-ray diffraction and Raman spectroscopy. By substituting cations in $LiTaO_3$ with $Al^{3+}$, the melting temperature was lowed and the ferroelectric properties can be improved. It is easier at lower temperature to fabricate the single crystal used for SAW filters and IR sensors. From the measured lattice constants and Raman band broadening, the solubility limit was X=0.25mol in $Li_{1-X}Al_{2X}Ta{1-X}O_3$, above which $Al_2O_3$ was obsered as a second phase. The Raman band of sintered $LiTaO_3$ was compared with that of the single crystal to see the effect of grain size on the band broadening.

• Journal of the Korean Magnetics Society
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• v.27 no.1
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• pp.30-34
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• 2017

In this report, we calculated the angular dependence of exchange bias ($H_{ex}$) by using single domain model in exchange coupled ferromagnetic (F)/antiferromagnetic (AF) bilayers, which results with AF thickness ($t_{AF}$) were used for the analysis of measured ones in NiFe/MnIr bilayers. Angular dependence of $H_{ex}$ calculated at $t_{AF}$ > $t_c$ showed typical unidirectional behaviors, however, calculated one at $0.5t_c$ < $t_{AF}$ < $t_c$ showed peculiar angular behaviors by fixed AF spins at specified angle near ${\theta}_H=90^{\circ}$. Angular dependence of $H_{ex}$ measured in NiFe/MnIr (20 nm) bilayers showed typical unidirectional behaviors. However, measured one in NiFe/MnIr (4 nm) bilayers showed mixed behaviors including both of unidirectional and peculiar angular behaviors, which was explained by the grain size distribution of polycrystalline MnIr.

• Transactions on Electrical and Electronic Materials
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• v.3 no.1
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• pp.14-17
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• 2002

The effects of substrate temperatures and annealing temperatures on the microstructures and ferroelectric properties of PbZ $r_{0.52}$ $Ti_{0.48}$ $O_3$(PZT) thin fims prepared by pulsed laser deposition (PLD) were investigated. For this purpose, the PZT films were deposited at various substrate temperatures (400~$600^{\circ}C$) with post annealing process in oxygen atmosphere. The single perovskite phase was formed at the deposition temperature of 500 to 55$0^{\circ}C$ without post annealing and the PZT films deposited below 50$0^{\circ}C$ formed the single phase with post annealing at $650^{\circ}C$. The grain size of the films increased and the grain boundary of the films was clearly defined as the substrate temperature increased from 400 to 55$0^{\circ}C$. The remnant polarization (Pr) and the coercive field (Ec) of the films deposited at 55$0^{\circ}C$ and annealed at $650^{\circ}C$ were 34.3 $\mu$C/c $m^2$and 60.2 kV/cm, respectively.y.y.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.6
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• pp.356-360
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• 2000

With isogenic waxy and non-waxy rice cultivars, growth responce as affected by leaf-removal treatment were examined in various fertilizer application. Vertical dry matter of culm was significantly decreased from ground upto 10cm. Culm dry matter of waxy rice was more steadily decreased than that of non-waxy rice. Starch content of culm in non-waxy rice was higher than waxy rice, and that in waxy and non-waxy rice were the lowest in three leaf-removal but no difference in single leaf-removal. Flag leaf in waxy rice and 2 nd leaf in non-waxy rice were dominantly affected yield by leaf-removal. The 1000-grain weight and rippend grain ratio of non-waxy rice were more higher than waxy rice and that in waxy and non-waxy rice were the lowest value in three leaf-removal but no difference in single leaf-removal treatments.

• Progress in Superconductivity and Cryogenics
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• v.11 no.2
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• pp.7-10
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• 2009

Effects of $BaCO_3$ purity on the superconducting properties of top seeded melt growth (TSMG) processed $Y_{1+x}Ba_2Cu_3O_{7-y}$ (Y1+x, x=0.1 and 0.2) superconductors were investigated. $YBa_2Cu_3O_{7-y}$ (Y123) powder prepared using $BaCO_3$ with 99.75% purity and commercially available Y123 powder of 99.9% were used for the fabrication of single Y123 grain superconductors. $T_c$ values of the Y1+x samples prepared using low purity Y123 powder were slightly lower than those of the samples prepared using a high purity powder. In addition to the lower $T_c$, an anomalous peak effect in the intermediate magnetic fields was observed in Y1+x samples prepared using the low purity $BaCO_3$ powder. The slight decrease in $T_c$ and the anomalous peak effect are ascribed to the possible incorporation of a Y123 phase with impurity elements such as strontium and calcium included in the $BaCO_3$powder of 99.7%. The result suggests that the low purity $BaCO_3$ powder of a low price can be used as a raw power for the fabrication of single grain YBCO bulk superconductors.

• Progress in Superconductivity and Cryogenics
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• v.6 no.1
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• pp.12-17
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• 2004

High critical current density. $J_c$ over $1MA/cm^2$ at 77 K in a self field was successfully achieved from the YBCO film prepared on (100) $SrTiO_3$ single-crystal substrates by the TFA-MOD process. Unlike a normal TFA-MOD process, we prepared the TFA precursor solution by dissolving YBCO powder into the trifluoroacetic acid. A significant amount of the second phases, including $BaF_2$, was observed in the films fired at $700-725^{\circ}C$ for 2 h under $P(O_2)=10^{-3}$ atm and $P(H_2O)=4.2%$, most probably due to an insufficient reaction time, and hence $T_c$ was greatly degraded. However the films fired at $750-800^{\circ}C$ for 2 h were composed of strongly c-axis oriented YBCO grams without any second phases. and exhibited the $T_c$ values of 89.5 ~ 91 K with a sharp transition. With increasing the firing temperature from 750 to $800^{\circ}C$ average grain size of YBCO was increased and grain connectivity was enhanced. The highest $J_c$ value of $1.1MA/cm^2$ was obtained from the YBCO film fired at $800^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.4
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• pp.292-297
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• 2003

We fabricated a single crystal silicon thin film transistor for active matrix organic light emitting displays(AMOLEDs) using silicon on insulator wafer (SOI wafer). Poly crystal silicon thin film transistor(poly-Si TFT) Is actively researched and developed nowsdays for a pixel switching devices of AMOLEDs. However, poly-Si TFT has some disadvantages such as high off-state leakage currents and low field-effect mobility due to a trap of grain boundary in active channel. While single crystal silicon TFT has many advantages such as high field effect mobility, low off-state leakage currents, low power consumption because of the low threshold voltage and simultaneous integration of driving ICs on a substrate. In our experiment, we compared the property of poly-Si TFT with that of SOI TFT. Poly-Si TFT exhibited a field effect mobility of 34 $\textrm{cm}^2$/Vs, an off-state leakage current of about l${\times}$10$\^$-9/ A at the gate voltage of 10 V, a subthreshold slope of 0.5 V/dec and on/off ratio of 10$\^$-4/, a threshold voltage of 7.8 V. Otherwise, single crystal silicon TFT on SOI wafer exhibited a field effect mobility of 750 $\textrm{cm}^2$/Vs, an off-state leakage current of about 1${\times}$10$\^$-10/ A at the gate voltage of 10 V, a subthreshold slope of 0.59 V/dec and on/off ratio of 10$\^$7/, a threshold voltage of 6.75 V. So, we observed that the properties of single crystal silicon TFT using SOI wafer are better than those of Poly Si TFT. For the pixel driver in AMOLEDs, the best suitable pixel driver is single crystal silicon TFT using SOI wafer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.2
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• pp.34-45
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• 1991

The fundamental conditions for growing $r-6Bi_2O_3{\cdot}GeO_2$ (BGO) single crystal plates by EFG (Edge -defined Film-fed Growth) method, were investigated and the characterization, quality test were carried out for obtained BGO single crystal plates. The optimum growing conditions determined in this study were as follows: ${\cdot}$ temperature gradient: 22^{\circ}C/cm