• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.221-225
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• 2007

We have prepared $\delta$-phase SbTe alloy with various Sb contents of 64, 72, and 76 at. % and investigated the phase change temperature, the crystal structures of $\delta$-phase SbTe alloy, and determined the ovonic threshold switching voltages with edge contact type phase transition dimensions. As a result, the crystallization temperature is slightly reduced from 126 to $122^{\circ}C$, whereas the melting temperature is not changed. The ovonic threshold switching voltage is reduced from 1.6 to 0.9 V as increasing the Sb content from 64 to 76 at. %. It is found that the reductions of crystallization temperature and the ovonic threshold switching voltage are closely related with the interplanar spacing between adjacent atomic layers and the stacking number of atomic layers in a unit cell.

• Korean Journal of Materials Research
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• v.16 no.7
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• pp.412-415
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• 2006

Te-doped $CoSb_3$ was prepared by the encapsulated induction melting, and its doping effects on the thermoelectric properties were investigated. Single phase ${\delta}-CoSb_3$ was successfully obtained by the subsequent annealing at 773 K for 24 hrs. Tellurium atoms acted as electron donors by substituting antimony atoms. Thermoelectric properties were remarkably improved by the appropriate doping. Dimensionless figure of merit was obtained to be 0.83 at 700K for the $CoSb_{2.8}Te_{0.2}$ specimen.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.106-107
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• 2007

A detailed investigation of cell structure and electrical characteristic in chalcogenide-based phase-change random access memory(PRAM) devices is presented. We used compound of Ge-Se-Te material for phase-change cell. Actually, the performance properties have been improved surprisingly then conventional Ge-Sb-Te. However, crystallization time was as long as ever for amorphization time. We conducted this experiment in order to solve that problem by doping-Sb with annealing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.156-157
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• 2007

For tens of years many advantages of Phase-Change Random Access Memory(PRAM) were introduced. Although the performance improved gradually, there are some portions which must be improved. So, we studied new constitution of $Ge_1Se_1Te_2$ chalcogenide material to improve phase transition characteristic. Actually, the performance properties have been improved surprisingly. However, crystallization time was as long as ever for amorphization time. We conducted this experiment in order to solve that problem by doping-Sb.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1274-1276
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• 1997

We have investigated the crystallization properties of $Te_x(Sb_{85}Ge_{15})_{100-x}$ (x=0.3, 0.5, 1.0 at.%) thin films as observing the reflectance change, XRD and SEM. The reflectance difference(${\Delta}R$) between amorphous and crystalline phases appears appoximately 20%, in all films, at 780nm(diode laser wavelength). In the case of $Te_{0.5}(Sb_{85}Ge_{15})_{99.5}$ thin film, especially, ${\Delta}R$ is about 30%. Also, amophous-to-crystalline phase change is observed at all films. Therefore, $Te_{0.5}(Sb_{85}Ge_{15})_{99.5}$ thin film can be evaluated as attractive optical recording material with low loss and high contrast ratio.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.215-215
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• 2010

The feasibility of InSbTe (IST) chalcogenide materials prepared by metalorganic chemical vapor deposition (MOCVD) for phase-change memory (PRAM) applications was demonstrated. Films grown below $225^{\circ}C$ exhibited an amorphous structure, and the films grown at $300^{\circ}C$ Cincluded various crystalline phases such as In-Sb-Te, In-Sb, In-Te, and Sb-Te. The composition of the amorphous films grown at $225^{\circ}C$ was dependent on the working pressure. Films grown at $225^{\circ}C$ exhibited a smooth morphology with a root mean square(rms) roughness of less than 1nm, and the step-coverage of the films grown on a trench structure with an aspect ratio of 5:1 was greater than 90%. An increase in deposition time increased the filling rate, while retaining the conformal step-coverage. Films grown at $225^{\circ}C$ for 3h in a working pressure of $13{\times}10^2$ Pa exhibited a reproducible and complete filling in a trench structure.

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.196-197
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• 2002

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.78-79
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• 2003

타원법(ellipsometry)을 사용하여 광기록 매체용 Ge$_2$Sb$_2$Te／sub 5／(GST) 박막의 성장과정에 따른 타원상수 Ψ와 $\Delta$를 측정하여, GST 박막의 최적성장조건을 연구하였다. 아르곤기체압력과 DC 출력 그리고 기판의 온도를 변화시키면서 GST 박막을 성장시켰다. 제작된 시료들의 분광타원 데이터를 모델링분석하여 GST 박막의 밀도분포를 구하고 한편으로는 GST 박막이 성장하는 동안 측정한 in situ 타원 성장곡선을 분석하여 박막의 밀도분포의 변화를 추적하였다. (중략)

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.520-527
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• 1999

As a new approache(extrusion-sintering process) to fabricate the thermoelectric materials, it has been at tempted to extrude and sinter the powders simultaneously. It was possible to produce the highly dense <$(Bi,Sb)_2(Te,Se)_3$-based thermoelectrics with sound surface appearances and microstructures by adjusting the process variables. For the p-type materials, the Seeback coefficient was increased with the amount of Te dopants, and the thermoelectric figure of merit appeared to be $2.5\times10^{-3}/K$ at room temperature when doped with 3 at % Te. The n-type specimen doped with 0.16 mol% $SbI_3$ showed the thermoelectric figure of merit of $1.8\times10^{-3}/K$. In both p-type an 우-type materials, the carrier mobility an the thermoelectric figure of merit parallel to the extrusion direction were higher than those perpendicular to it.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2167-2170
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• 2013

A low-cost and simple recycling process of waste thermoelectric modules has been investigated using chemical reduction methods. The recycling is separated by two processes, such as dissolving and reduction. When the waste thermoelectric chips are immersed into a high concentration of $HNO_3$ aqueous solution at $100^{\circ}C$, oxide powders, e.g., $TeO_2$ and $Sb_2O_3$, are precipitated in the $Bi^{3+}$ and $HTeO{_2}^+$ ions contained solution. By employing a reduction process with the ions contained solutions, $Bi_2Te_3$ nanoparticles are successfully synthesized. Due to high reduction potential of $HTeO{_2}^+$ to Te, Te elements are initially formed and subsequently $Bi_2Te_3$ nanoparticles are formed. The average particle size of $Bi_2Te_3$ was calculated to be 25 nm with homogeneous size distribution. On the other hand, when the precipitated powders reduced by hydrazine, $Sb_2O_3$ and Te nanoparticles are synthesized because of higher reduction potentials of $TeO_2$ to Te. After the washing step, the $Sb_2O_3$ are clearly removed, results in Te nanoparticles.