• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.33-38
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• 2011

The p-type $(Bi_{0.2}Sb_{0.8})_2Te_3$ powers were fabricated by mechanical alloying and hot-pressed at temperatures of $350{\sim}550^{\circ}C$. Themoelectric properties of the hot-pressed $(Bi_{0.2}Sb_{0.8})_2Te_3$ were characterized as a function of the hot-pressing temperature. With increasing the hot-pressing temperature from $350^{\circ}C$ to $550^{\circ}C$, the Seebeck coefficient and the electrical resistivity decreased from 237 ${\mu}V/K$ to 210 ${\mu}V/K$ and 2.25 $m{\Omega}-cm$ to 1.34 $m{\Omega}-cm$, respectively. The power factor of the hot-pressed $(Bi_{0.2}Sb_{0.8})_2Te_3$ became larger from $24.95{\times}10^{-4}W/m-K^2$ to $32.85{\times}10^{-4}W/m-K^2$ with increasing the hot-pressing temperature from $350^{\circ}C$ to $550^{\circ}C$. Among the specimens hot-pressed at $350{\sim}550^{\circ}C$, the $(Bi_{0.2}Sb_{0.8})_2Te_3$ hot-pressed at $500^{\circ}C$ exhibited the maximum dimensionless figure-of-merit of 1.09 at $25^{\circ}C$ and 1.2 at $75^{\circ}C$.

• Reproductive and Developmental Biology
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• v.31 no.3
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• pp.193-198
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• 2007

The present study was examined the expression patterns of cdx2 gone, n lineage marker, in the mouse and bovine developmental stage embryos and whether one blastomere of two- and/or four-cell bovine embryos develop to specific lineage (ICM or TE) of blastocyst by injection of Texas red conjugated dextran as a lineage tracer. It was also investigated the allocation of ICM and n cells in bovine blastocysts derived from one blastomere of two-and/or four-cell stage embryos. Firstly, it was observed that expression of cdx2 appeared symmetric and asymmetric distribution at the two-cell stage mouse embryos. from four-cell to morula stage mouse embryos, the expression of cdx2 gene was observed in almost all blastomeres. In case of bovine embryos, localization of cdx2 was similar to pattern of mouse embryos. The Dextran-labeled blastomere of two- and/or four-cell embryos contributed to both ICM and TE cells in bovine blastocysts. And also, it was confirmed that a single blastomere derived from two-cell stage bovine embryos could develop to the normal blastocyst with both ICM and TE cells. These results show that two-and/or four-cell stage is not the specific stage to determine the cell rate for ICM and TE, and which is not correlated with the expression of cdx2 gene.

• Korean Journal of Animal Reproduction
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• v.20 no.3
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• pp.279-288
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• 1996

The objective of this study was to determine the effect of EGF on the development of IVM/IVF bovine embryos and their ICM and TE cell number. In addition, we examined the combined effect of EGF and coculture to the bovine embryo development and the expression of EGF-R protein on bovine embryos by indirect immunofluorescence. The results obtained in these experiments were summarized as follows: When the IVM/IVF 4- to 8-cell embryos were treated at 0, 1, 10, 100 ng/ml of EGF, EGF treatment group showed improved development to blastocyst and increased pattern of ICM and TE cell number compared with control, although there is not significantly different. The stimulating effect of EGF (10 ng/ml) to the develop ment level of IVM/IVF bovine embryos significantly increased development rate to blastocyst after 8-cell stage (p<0.05), although there is no significant effect to the increase of ICM and TE cell numbers. Also, expression of EGF-R on the bovine embryonic stage by indirect immunofluor escence presents after 4-cell stage and the intensity of the EGF-R staining was variable with the development progression. On the other hand, embryos cultured in coculture group added either with or without EGF commonly indicated the significant difference in development rate to blastocyst and Total cell number compared with control. These results suggest that the a addition of EGF to the coculture may stimulate the coculture effect between IVM/IVF bovineembryos and cumulus cells. Therefore, EGF could promote preimplantation bovine embryo development by binding with expressed EGF~R after 4-cell stage, and stimulate the production of embryotrophic factors from the coculture environment. Also, the present study showed that there was no significant effect of EGF to the increase of ICM and TE cell number although the rate of blastocyst significantly increased when treated with EGF after 8-cell stage (p<0.05).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.1
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• pp.44-49
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• 2022

In this paper, we investigated current (I)- and voltage (V)-sweeping properties in a double-stack structure, Ge₂Sb₂Te₅/Ti/W-doped Ge₈Sb₂Te₁₁, a candidate medium for applications to multilevel phase-change memory. 200-nm-thick and W-doped Ge₂Sb₂Te₅ and W-doped Ge₈Sb₂Te₁₁ films were deposited on p-type Si(100) substrate using magnetron sputtering system, and the sheet resistance was measured using 4 point-probe method. The sheet resistance of amorphous-phase W-doped Ge₈Sb₂Te₁₁ film was about 1 order larger than that of Ge₂Sb₂Te₅ film. The I- and V-sweeping properties were measured using sourcemeter, pulse generator, and digital multimeter. The speed of amorphous-to-multilevel crystallization was evaluated from a graph of resistance vs. pulse duration (t) at a fixed applied voltage (12 V). All the double-stack cells exhibited a two-step phase change process with the multilevel memory states of high-middle-low resistance (HR-MR-LR). In particular, the stable MR state is required to guarantee the reliability of the multilevel phase-change memory. For the Ge₂Sb₂Te₅ (150 nm)/Ti (20 nm)/W-Ge₈Sb₂Te₁₁ (50 nm), the phase transformations of HR→MR and MR→LR were observed at t<30ns and t<65ns, respectively. We believe that a high speed and stable multilevel phase-change memory can be optimized by the double-stack structure of proper Ge-Sb-Te films separated by a barrier metal (Ti).

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.3
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• pp.1-6
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• 1990

When TE waves incident to the infinite conductor grating plane, current distributions on the strip is found by the spectral domain analysis and the moment method. Current distributions on the strip as the parameter of incident angle of waves are calculated for the grating plane of which strip space is $0.05{\lambda}{\sim}5{\lambda}$, and of which the ration of strip width to its space is 0.4 - 0.8 . In order to varify the validity of the present method, the numerical results are compared with other method.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.839-842
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• 2009

In this paper, chalcogenide glasses material(Se, Te, Sb) is firstly used as encapsulation layer of OLEDs under high vacuum of $10^{-4}$Pa. In the experiments, properties of OLEDs encapsulated by Se, Te, Sb thin film is compared with that of device encapsulated by traditional method. It is found that Se, Te, Sb film can extend lifetime of devices to 1.4, 2, 1.3 times respectively. Chalcogenide glasses film as encapsulation layer has little effect on some characteristics of device. The research indicated that OLEDs can be well protected upon applying Se, Te, Sb film as encapsulation layer. It is clear that it can prolong the lifetime obviously.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.4
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• pp.135-139
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• 2015

$Bi_2Te_3-Bi_2Se_3$ alloy which is typical n-type thermoelectric material were grown by traveling heater method (THM) technique. We investigate the effect of the composition of $100-x(Bi_2Te_3)-x(Bi_2Se_3)$ and doping of n-type dopants such as $SbI_3$ and $CdCl_2$. Maximum figure of merit of $Bi_2Te_3-Bi_2Se_3$ alloy was observed with $CdCl_2$ 0.1 wt% (Z: $2.73{\times}10^{-3}/K$) and $SbI_3$ 0.05 wt% (Z: $2.29{\times}10^{-3}/K$). Deviation along the length of $Bi_2Te_3-Bi_2Se_3$ ingot grown by THM method is low, which indicates that the ingot is very homogenized. Also we observed the close relationship of between anisotropy ratio and dopant in the $90(Bi_2Te_3)-10(Bi_2Se_3)$ alloys. And we confirmed the fact that anisotropy ratio exerts thermoelectric performance in $Bi_2Te_3$ based n-type thermoelectric material.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.4
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• pp.171-174
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• 2004

The $Ag_2Te$ crystal was grown by the Bridgman method. The $Ag_2Te$ crystal was an monoclinic structure with lattice constance a = $8.1686{\AA}$, b = $9.0425{\AA}$, c = $8.0065{\AA}$. Hall effect shows a n-type conductivity in the $Ag_2Te$ crystal. The electrical resistivity was 1.080e-$3{\Omega}cm$ and electron mobility was $-5.48{\times}10^3cm^2/V{\cdot}sec$ at room temperature(RT).

• Journal of the Korean Ceramic Society
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• v.42 no.5 s.276
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• pp.326-332
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• 2005

Phase transformation effects on mechanical properties of $Ge_2Sb_2Te_5$, which is a promising candidate material for Phase Change Random Access Memory (PRAM), were studied. $Ge_2Sb_2Te_5$ thin films, which was thermally annealed with different conditions, were analyzed using XRD, AFM, 4-point probe method and reflectance measurement. As the temperature and the dwelling time increased, crystallity and grain size increased, which enhanced elastic modulus and hardness. Furthermore, N2 doping, which was used for better electrical properties, was proved to decrease elastic modulus and hardness of $Ge_2Sb_2Te_5$.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.158-158
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• 2003

수평 전기로에서 CuGaTe2 다결정을 합성하여 HWE 방법으로 CuGaTe2 단결정 박막을 반절연성 GaAs(100) 위에 성장하였다. CuGaTe2 단결정 박막은 증발원과 기판의 온도를 각각 67$0^{\circ}C$, 41$0^{\circ}C$로 성장하였다. 이때 단결정 박막의 결정성이 10K에서 측정한 광발광 스펙트럼은 954.5nm (1.2989eV) 근처에서 exciton emission 스펙트럼이 가장 강하게 나타났으며, 또한 이중결정 X-선 요동곡선(DCRC)의 반폭치(FWHM)도 139arcsec로 가장 작게 측정되어 최적 성장 조건임을 알 수 있었다. Hall 효과는 van der Paw방법에 의해 측정되었으며, 온도에 의존하는 운반자 농도와 이동도는 293K에서 각각 8.72$\times$$10^{23}$개/㎥, 3.42$\times$$10^{-2}$$m^2$/V.s였다. 상온에서 CuGaTe2 단결정 박막의 광흡수 특성으로부터 에너지 띠간격이 1.22 eV였다 Band edge에 해당하는 광전도도peak의 온도 의존성은 Varshni 관계식으로 설명되었으며, Varshni 관계식의 상수값은 Eg(0) = 1.3982 eV, $\alpha$= 4.27$\times$$10^{-4}$ eV/K, $\beta$= 265.5 K로 주어졌다. CuGaTe2 단결정 박막의 광전류 단파장대 봉우리들로부터 10K에서 측정된 $\Delta$cr (crystal Field splitting)은 0.0791eV, $\Delta$s.o (spin orbit coupling)는 0.2463eV였다. 10K에서 광발광 봉우리의 919.8nm (1.3479eV)는 free exciton(Ex), 954.5nm (1.2989eV)는 donor-bound exciton 인 I2(DO,X)와 959.5nm (1.2921eV)는 acceptor-bound exciton 인 I1(AO,X) 이고, 964.6nm(1.2853eV)는 donor-acceptor pair(DAP) 발광, 1341.9nm (0.9239eV)는 self activated(SA)에 기인하는 광발광 봉우리로 고찰되었다.