• 한국결정성장학회지
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• 제23권2호
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• pp.93-100
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• 2013

지구 온난화의 대표적인 주범인 $CO_2$를 저감하기 위하여 많은 연구가 진행되고 있다. 특히 가스 하이드레이트 형성원리를 이용한 $CO_2$ 분리 및 저장 공정이 주목을 받고 있다. 본 연구는 필름형 $CO_2$ 하이드레이트의 결정성장 거동에 관하여 성장 메커니즘을 규명하였다. 다양한 압력조건에서 반회분식 교반 반응기를 이용하여 $CO_2$ 하이드레이트를 형성시켰으며 객체가스의 용해도 차이를 최소화하기 위하여 모든 실험에서 온도는 고정하였다. 공급된 가스는 순도 99.999 %의 $CO_2$ 가스를 사용하였고, CCD 카메라(Nikon DS-5M/Fi1/2M-U2)가 장착된 광학현미경을 사용하여 관찰 결과를 실시간 기록하였다. 실험에 적용되는 압력에 따라서 하이드레이트 성장형태와 성장속도는 매우 큰 차이를 보였다. 특히 2.0 MPa 이상의 압력에서 가장 큰 변화를 관찰하였으며, 이것은 $CO_2$의 농도 차이와 모세관 힘에 의한 것으로 사료된다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 13th KACG Technical Meeting `97 Industrial Crystallization Symposium(ICS)-Doosan Resort, Chunchon, October 30-31, 1997
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• pp.1-5
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• 1997

The growth mechanism of AMT(Ammonium Meta-Tungstate) crystal was interpreted as two-step model. The contribution of the diffusion step increased with the increase of temperature, crystal size, and supersaturation. The crystal size distribution from a batch cooling crystallizer was predicted by the numerical solution of a mathematical model which uses the kinetics of nucleation and crystal growth. Temperature control of a batch crystallizer was studied using Learning control algorithm. The purity of AMT crystal producted in this investigation was above 99.99%.

• 한국결정성장학회지
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• 제1권1호
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• pp.66-73
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• 1991

During the growth of macroscopically dislocation-free Czochralski silicon crystal, micro precipitates causing stacking faults in the silicon wafer during the oxidation are formed Thermal history the cryscausing acquire during the growth process is known to be a key factor determining the nucleation of this micro precipitates. In this article, various mechanisms suggested on the formation of microdefects in the silicon crystal are reviewed to secure the nucleation mechanism of the micro precipitates causing OSF whose pattern is normally ring or annular in CZ silicon crytal. B-defects which are known as vacancy clustering are considered to be the heterogeneous nucleation sites for the micro precipitates causing OSF in the CZ silicon crystals.

• 한국결정성장학회지
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• 제10권1호
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• pp.13-16
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• 2000

Progress in Si crystal and wafer technologies is discussed on single crystal growth, wafer fabrication, epitaxial growth, gettering, 300 mm and SOI. As for bulk crystal growth, the mechanism of grown-in defects (voids) formation, the succes of grown-in defect free crystal growth technology and nitrogen doped crystal are shown. New wafer fabrication technologies such as both-side mirror polishing and etchingless process have been developed. The epitaxial growth of SiGe/Si heterostructure for high speed bipolar device is treated. Gettering technology under low temperature process such as RTP is important, and also it is shown that IG effect for Ni could be predicted using computer simulation of precipitate density and size. The development of 300 mm wafer and SOI has made progress steadily.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 The 9th KACG Technical Annual Meeting and the 3rd Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.399-421
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• 1996

(1) The solute distribution mechanism was analyzed for the Si0.95Ge0.05 single crystal fiber by u-PD method. (2) The steady-state solutions were obtained for the molten zone and the capillary zone. (3) The effect of the convection in the molten zone on partitioning was not significant for many cases. (4) Intermediate transient rise of Ge was shown by the sudden change of the growth velocity or molten zone height. (5) Periodic compositional modulation can be designed by using the intermediate transient.

• 한국세라믹학회지
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• 제31권3호
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• pp.249-256
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• 1994

By surface structure and X-ray topographic observation, growth mechanism of NAB single crystal grown by TSSG technique using a BaB4O7 flux was studied. Surface structure of grown crystals were investigated by optical microscope. Growth history and crystal defects included within grown crystal were investigated using X-ray topography. The {001} faces were grown by 2-D nucleation growth. As decreasing cooling rate, growth mechanism of {111} and {11} was changed from 2-D nucleation growth to the growth by screw dislocation. Only surface striations developed parallel to a-axis were observed on {010} faces. Growth sector of NAB crystals were divided into {001}, {111}, {010}, {021}, {11}. The inclusion which was usually trapped between {001} faces was investigated.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.51-59
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• 2012

Piezoelectric langasite crystals have superior properties such as high temperature performance and high quality Q and can be applied in combustion pressure sensors and surface acoustic wave (SAW) filters. Crystal growth, crystal structure and properties of langasite group are reviewed, and the mechanism of piezoelectricity of langasite is presented based on the crystal structure and deformation under high pressure. Finally, for the discovery of new piezoelectric materials, this paper presents the role of the framework, and recommends the search of framework crystal structure, because the characteristic of the mechanism exists on the framework of the crystal structure.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3397-3406
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• 2012

Three types of spherulitic morphologies have been investigated in dual substrate mode of Belousov-Zhabotinsky (BZ) type reaction system. Prior to growth of spherulites, three distinct patterning behaviors have been observed sequentially during the reaction process. Initial and the early-phase of reaction showed the emergence of concentric ring-like wave patterns. A colloidal-state of reaction consists of numerous fine solid particles, which forms primarily some nucleation centers of dendritic characters. The nucleation centers were found to grow in sizes and shapes with the progress of reaction. It leads to growth of dendritic-like spherulitic crystal patterns. The resultant spherulites showed transitions in their morphologies, including sea-weeds and rhythmic spherulitic crystal patterns, by the effects substituted organic substrate and in the higher concentration of bromate-initiator respectively. The branching mechanism and crystal ordering of spherulitic textures were studied with help of optical microscope (OPM) and scanning electron microscope (SEM). Characteristics of crystal phases were also evaluated using X-ray diffraction (XRD) and differential thermal analysis (DTA). Results indicated that the compositions of reactants and crystal orderings were interrelated with morphological transitions of spherulites as illustrated and described.

• 한국결정성장학회지
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• 제9권5호
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• pp.454-458
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• 1999

Hydrodynamic Thermal Capilary Model developed previously has been modified to study the transport phenomena in the Czochralski process. Our analysis is focused on the heat transfer in the system, convection in the melt phase, and the meniscus and interface shape. Four major forces drive melt flow in the crucible, which include thermal buoyancy force in the melt, thermocapillary force along the curved meniscus, crucible rotation and crystal rotation. Individual flow mechanism due to each driving force has been examined to determine its interaction with the meniscus and interface shape. A nominal 4-inch-diameter silicon crystal growth process is chosen as a subject for analysis. Heater temperature profile for constant diameter crystal is also present as a function of crystal height or fraction solidified.

• 한국결정성장학회지
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• 제7권2호
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• pp.185-190
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• 1997

승화법에 의한 단결정 성장장치를 자체 제작하여 직경 약 30 mm, 길이 약 10 mm의 6H-Sic 단결정을 성장하였다. 최적의 성장조건은 원료온도 $2150~2250^{\circ}C$, 기판온도 $1950~2050^{\circ}C$, 원료부와 기판과의 온도차 약 $200^{\circ}C$, 성장압력 50~200 torr이었고, 성장속도는 300~700 $\mu\textrm{m}$/hr이었다. 성장된 결정의 표면을 광학현미경으로 관찰하여 성장결함 생성기구를 현상학적으로 고찰하였고, 특히 표면에서 관찰되는 micropipes의 생성원인을 규명하였다.