• 한국결정학회지
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• 제14권2호
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• pp.62-66
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• 2003

VGF법을 사용하여 CuBr₂ dopant가 첨가된 Bi₂Te/sub 2.55/Se/sub 0.45/ 열전재료를 제조하였다. 이 방법을 사용하여 일방향으로 성장된 Bi₂Te/sub 2.55/Se/sub 0.45/ 잉곳의 제조가 가능하였으며 XRD 분석 결과 우선성장 방향이 (0 1 5)면임이 밝혀졌다. 본 실험을 통하여 제조한 열전재료의 Seebeck 계수와 전기전도도를 373∼523 K 범위에서 측정하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2001년도 추계 학술발표강연 및 논문개요집
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• pp.102-102
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• 2001

• 대한약침학회지
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• 제21권1호
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• pp.35-40
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• 2018

Objective: The role of BDNF (brain-derived neurotrophic factor), CREB (cAMP response element binding) and VGF neuropeptide has been proved in antidepressant activity of long term saffron administration in the rat hippocampus. In this study we evaluated the role of these proteins in antidepressant activity of saffron in long term administration in the rat cerebellum. Methods: Saffron aqueous extract (40 and 80 mg/kg/day) and imipramine (10 mg/kg/day) were administered intraperitoneally for 21 days to rats. At the end of experiment, animals were sacrificed and cerebellums were separated. The protein levels of BDNF, VGF, CREB and P- CREB in the rat cerebellum were evaluated using western blot analysis. Results: Saffron aqueous extract (80mg/kg/day) caused significant increase in protein level of P-CREB in long term treatment in the rat cerebellum. The increases in the protein levels of VGF, CREB and BDNF were not significant. Conclusion: In summary, our results showed that antidepressant effect of saffron in rat cerebellum might be due to the enhanced phosphorylation of CREB.

• 한국결정성장학회지
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• 제4권1호
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• pp.33-41
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• 1994

단결정 성장과정에서 고액계면의 위치와 형상이 결정의 품질에 영향을 준다는 사실은 이미 잘 알려져 있다. 따라서 이를 결정해 주는 노내 온도분포의 파악은 매우 중요하다. 본 연구에서는 VGF 단결정법을 대사응로 발열체의 온도만을 이용하여 노내 온도분포를 구할 수 있는 프로그램을 개발하였으며,이를 사용하여 지지봉 및 도가니의 재질과 크기가 고액계면의 형상에 미치는 영향을 검토해 보았다. 지지봉의 반경이 클수록, 열전도도가 작을수록 평활한 고액계면이 나타나 . 열전도도가 등방성을 가진 도가니의 경우, 열확산계수의 증가에 따라 고액계면이 더 오목해지는 경향을 보였다. PBN과 석영 도가니의 계산 결과 비교를 통하여 도가니 열전도돋의 이방성이 고액계면에 미치는 영향을 고찰해 본 결과, 계면의 위치에 따라서 다른 양상을 보인다는 것을 알았다.것을 알았다.

• 한국결정성장학회지
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• 제1권1호
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• pp.17-25
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• 1991

The construction details of VGF apparatus with a DM(direct monitoring) furnace for the growth of low defect crystal and characteristics of GaAs crystal grown by this apparatus are described. The average dislocation densities and EL2 concentration of as-grown undoped GaAs along the different solidified fractions exhibit $4{\times}10^{2}-7{\times}10^{3}cm^{-2}$ and $6{\times}10^{14}-4{\times}10^{15}cm^{-3}$, which are less than those observed for liquid encapsulated Czochralski(LEC) or high-pressure vertical gradient freeze(VGF) crystals. These remarkable reduction of the dislocation densities and EL2 concentrations were explained by the lower temperature gradient ($dT/dx-10^{\circ}/cm$) and slower rates of post - growth cooling ($20^{\circ}C/hr:1240-1000^{\circ}C,\;30^{\circ}C/hr:1000-700^{\circ}C$). Also, The Hall mobilities, carrier concentrations show uniform distribution throughtout 80% of the ingot length.

• 한국결정성장학회지
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• 제19권2호
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• pp.75-78
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• 2009

PBN 도가니를 이용하여 Si이 도핑된 GaAs 단결정을 수직경사 응고법으로 성장시켰다. PBN 도가니에 산화막인 $B_{2}O_{3}$의 양을 $0{\sim}0.2wt%$ 범위에서 변화시키면서, 성장 후 캐리어 농도를 측정하였다. $B_{2}O_{3}$ 첨가량이 증가함에 따라, 초기 0.1 정도의 Si 도판트의 편석계수는 0.01 부근까지 급격히 감소하고, 동시에 캐리어 농도도 감소하는 것을 알 수 있었다. 이는 성장도중 도판트인 Si이 $B_{2}O_{3}$과 반응하며 도너인 Si 양을 감소시키며, 동시에 억셉터인 B 양을 증가시키기 때문으로 보인다. 한편 PBN 도가니 내면에 얇은 유리질의 $B_{2}O_{3}$층 형성이 용이한 고온 산화막 처리가 결함감소에 효과적임을 확인하였다.

• 한국결정학회지
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• 제1권2호
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• pp.115-125
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• 1990

We have investigated bulk and hetero-epitaxial growth of GaAs single crystal. Various growth techniques such as HB, HZM, and VGF for high quality bulk GaAs were successfully developed by appling the specially designed DM(direct monitoring) furnace. Al GaAs/GaAs superlattice structure and In(x)Ga(1-x) As/GaAs epilayers were also grown by MOCVD and VPE, respectively. The characterization of GaAs single crystals and epilayers was made by X-ray diffraction, Hall effect, PL, chemical etching and angle lapping technique.

• 한국결정성장학회지
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• 제9권6호
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• pp.542-546
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• 1999

InP single crystal, III-V binary compound semiconductor, was grown by VGF(vertical gradient freeze) method using quartz ampoule and its electrical optical properties were investigated. Phosphorous powders were put in the bottom of quartz ampoule and Indium metal charged in conical quartz crucible what was attached at the upper side position inside the quartz ampoule. It was vacuous under the pressure of $10^5$Torr and sealed up. Indium metal was melted at $1070^{\circ}C$ and InP composition was formed by diffusion of phosphorous sublimated at $450^{\circ}C$ into Indium melt. By cooling the InP composition melt ($2^{\circ}C$~$5^{\circ}C$/hr of cooling rate) in range of $1070^{\circ}C$~$900^{\circ}C$, InP crystal was grown. The grown InP single crystals were investigated by X-ray analysis and polarized optical microscopy. Electrical properties were measured by Van der Pauw method. At the cooling method. At the cooling rate of $2^{\circ}C$/hr, growth direction of ingot was [111] and the quality of ingot was better at the upper side of ingot than the lower side. It was found that the InP crystals were n-type semiconductor and the carrier concentration, electron mobility and relative resistivity were $10^{15}$~$10^{16}/\textrm{cm}^3$ , $2\times 10^3$~$3\times 10^4{\textrm}{cm}^2$/Vsec and$2\times 10^{-1}$~$2\times 10^{-3}$/ Wcm in the range of 150K~300K, respectively.

• 한국결정학회지
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• 제7권1호
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• pp.81-87
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• 1996

석영 boat를 반응용기로 쓰는 수평 Bridgman 법에서, GaAs 단결정에 유입되는 Si 농도를 Ga-As 계의 상평형에 근거한 열역학적 평형을 가정하여 성장방법 별로 계산하였고, Hall 측정에 의한 전자 농도 측정치와 비교하였다. 단일 온도대역 수평 Bridgman(1-T HB) 법의 경우 Si 농도의 계산치가 5.3 ×10 15(atoms/cm3)인데 비해 실험치는 9.8 ×10 15(/cm3) 이었고, 이중 온도대역 수평 Bridgman(2-T HB) 법에서는 계산치가 1.1 ×10 16(atoms/cm3), 측정치가 1.5 ×10 16(/cm3) 인 것으로 각각 나타났다. 한편 1-T나 2-T HB 법에 비하여 성장시간이 절반 정도인 VGF(vertical gradient freeze) 방법의 경우 이론치와 실험치가 비교적 일치 하였고 그 값은 (6∼8) ×10 15 (atoms/cm3)인 것으로 나타났다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1999년도 PROCEEDINGS OF 99 INTERNATIONAL CONFERENCE OF THE KACG AND 6TH KOREA·JAPAN EMG SYMPOSIUM (ELECTRONIC MATERIALS GROWTH SYMPOSIUM), HANYANG UNIVERSITY, SEOUL, 06월 09일 JUNE 1999
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• pp.419-431
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• 1999

InP, III-V binary compound semiconductor, single crystal was grown by VGF (vertical gradient freeze) method using quartz ampoule and its electrical optical properties were investigated. Phosphorous powders were put in the bottom of quartz ampoule and Indium metal changed in conical quartz crucible hat was attached at the upper side position inside the quartz ampoule. It was vacuous under the pressure of 10-5 Torr and sealed up. In metal in the quartz crucible was melted at 1070$^{\circ}C$ and phophorous sublimated at 450$^{\circ}C$, there after it was diffused in In melt and so InP composition was formed. By cooling the InP composition melt (2$^{\circ}C$∼5$^{\circ}C$/hr of cooling rate) in range of 1070$^{\circ}C$∼900$^{\circ}C$, InP crystal was grown. the grown InP single crystals were investigated by X-ray analysis and polarized optical microscopy. Electrical properties of them were measured by Van der Pauw method. At the cooling rate of 2$^{\circ}C$/hr, its direction was (111), quality of the ingot ws better upper side of the ingot than lower. It was found that the InP crystals were n-type semiconductor and the carrier concentration, electron mobility and relative resistivity were 1015∼1016/㎤, 2x103∼3x104$\textrm{cm}^2$/Vsec and 2x10-1∼2x10-3Ωcm in the range of 150K∼300K, respectively.