• Analytical Science and Technology
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• v.5 no.2
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• pp.213-216
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• 1992

Semiinsulating GaAs crystals employing LPLEC technique should be grown from the Ga-rich melt due to a very low incorporation of unintentional impurities such as carbon (<$10^{15}cm^{-3}$). High resisitivity of this material can be derived from the balanced compensation among not only EL2 deep donors and carbon acceptors but also H1 double charge native acceptors(Ev + 77meV, Ev + 200 meV) and H2 native acceptors(Ev + 68 meV). Considering of the complicated compensation mechanism using statistical calculation of the electron occupancy of each level, SI GaAs crystal with low impurity contents(<$10^{15}cm^{-3}$) can be successfully obtained by maintaining the melt composition around 0.45 As mole fraction.

• Journal of the Korean Ceramic Society
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• v.43 no.8 s.291
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• pp.509-514
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• 2006

In this study, chopped Hi-Nicalon SiC fiber Reinforced Porous Reaction Bonded SiC (RBSC) composites and it fabrication process were developed by using Si melt infiltration process. The porosity and average pore size in fabricated chopped SiC fiber reinforced porous RBSC composites were in the range of $30{\sim}40%$ and $40-90{\mu}m$, which mainly determined by the SiC powder size used as starting material and amount of residual Si in porous composites. The maximum flexural strength of chopped SiC fiber reinforced porous RBSC composite was as high as 80 MPa. The delayed fracture behavior was observed in chopped SiC fiber reinforced porous RBSC composites upon 3-point bending strength test.

• Journal of the Korean Ceramic Society
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• v.37 no.11
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• pp.1119-1125
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• 2000

용융 Si 침윤 방법에 의한 새로운 다공질 RBSC 제조공정이 개발되었으며, 용융 Si 침윤공정 방법으로 제조된 다공질 RBSC의 최대 3-점 파괴 강도는 18 MPa, 최대 기공율은 46% 범위이었다. 용융 Si 침윤방법으로 제조된 다공질 RBSC의 기계적 특성 및 기공율은 성형체내 SiC 입자 표면의 카본 source의 양 및 침윤시 사용된 Si의 양에 직접적으로 영향을 받는 것으로 나타났다. 침윤시 상대 Si 양은 40%를 사용하였으며, SiC 입자 표면에 graphite와 phenol resin을 함께 코팅한 성형체를 사용하여 제조된 다공질 RBSC에서 최대 파괴강도 값을 얻었다. 상대 Si의 양의 증가는 다공질 RBSC의 파괴강도를 감소시켰으며, SiC 입자 표면의 카본 source 코팅층은 graphite와 phenol resin을 같이 사용하였을 때 다공질 RBSC의 파괴강도는 증가되었으나, RBSC 내 기공율은 감소되었다.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.369-380
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• 2020

Most mono-crystalline silicon ingots are manufactured by the Czochralski (Cz) process. But If there are oxygen impurities, These Si-ingot tends to show low-efficiency when it is processed to be solar cell substrate. For making single-crystal Si- ingot, We need Czochralski (Cz) process which melts molten Si and then crystallizing it with seed of single-crystal Si. For melts poly Si-chunk and forming of single-crystalline Si-ingot, the heat transfer plays a main role in the structure of Cz-process. In this study to obtain high-quality Si ingot, the Cz-process was modified with the process design. The crystal growth simulation was employed with pulling rate and rotation speed optimization. Studies for modified Cz-process and the corresponding results have been discussed. The results revealed that using crystal growth simulation, we optimized the oxygen concentration of single crystal silicon by the optimal design of the pulling rate, rotation speed and melt charge level of Cz-process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.3
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• pp.120-125
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• 2002

Si-wafers for solar cells were cast in a size of $50{\times}46{\times}0.5{\textrm}{mm}^3$ by vacuum casting method. The graphite mold coated by BN powder, which was to prevent the reaction of carbon with the molten silicon, was used. Without coating, the wetting and reaction of Si melt to graphite mold was very severe. In the case of BN coating, SiC was formed in the shape of tiny islands at the surface of Si wafer by the reaction between Si-melt and carbon of the graphite mold on the high temperature. The grain size was about 1 mm. The efficiency of Si solar cell was lower than that of Si solar cell fabricated on commercial single and poly crystalline Si wafer. The reason of low efficiency was discussed.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.207-209
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• 1997

Influences of boron addition on the oxygen solubiligy in silicon melt and the amount of evaporation loss from the melt surface were investigated. It has been found the oxygen concentration increases from 2${\times}$1018 to 4${\times}$1018 atoms/㎤. The amount of evaporation loss was found to vary widely depending on the melt temperature. The amount of SiO evaporating form boron doped (∼102121 atoms/㎤) silicon melt at 1550$^{\circ}C$ is about twice as much as the value of non-doped melt.

• Journal of Electrochemical Science and Technology
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• v.10 no.1
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• pp.82-88
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• 2019

Here, we report on nanocrystalline Si-Al-M (M = Fe, Cu, Ni, Zr) alloys for use as an anode for lithium-ion batteries, which were fabricated via a melt-spinning method. Based on the XRD and TEM analyses, it was found that the Si-Al-M alloys consist of nanocrystalline Si grains surrounded by an amorphous matrix phase. Among the Si-Al-M alloys with different metal composition, Ni-incorporated Si-Al-M alloy electrode retained the high discharge capacity of 2492 mAh/g and exhibited improved cyclability. The superior $Li^+$ storage performance of Si-Al-M alloy with Ni component is mainly responsible for the incorporated Ni, which induces the formation of ductile and conductive inactive matrix with crystalline Al phase, in addition to the grain size reduction of active Si phase.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.446-461
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• 2005

본 연구에서는 반응소결 탄화규소 다공질 지지체 개발을 위하여 SiC/C로 이루어진 성형체를 사용한 Si melt infiltration 공정 및 SiC/C/Si으로 이루어진 성형체를 사용하는 Si embedding 공정 개발이 이루어졌다. 개발된 반응소결 탄화규소 다공질 지지체의 기공률은 38% 이상이었으며 평균기공은 130 ${\mu}m$ 크기이었다. Si melt infiltration 방법으로 제조된 반응소결 탄화규소 다공질 지지체의 파괴강도는 상용 반응소결 탄화규소 지지체의 파괴강도보다 최대 200% 이상 높게 나타났다. 본 연구에서는 용융 Si의 침윤공정을 이용하여 반응소결 탄화규소 여과층을 갖는 반응소결 탄화규소 필터 및 그 제조공정이 개발되었다. 개발된 반응소결 탄화규소 필터의 필터 특성은 상용 탄화규소 필터의 필터 특성과 대체적으로 대등한 것으로 조사되었다.

• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.287-294
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• 2012

Ceramic Matrix Composites (CMCs) represent a class of non-brittle refractory materials for harsh and extreme environments in aerospace and other applications. The quasi-ductility of these structural materials depends on the quality of the interface between the matrix and the fiber surface. In this study, a manufacture route is described where in contrast to most other processes no additional fiber coating is used to adjust the fiber/matrix interfaces in order to obtain damage tolerance and fracture toughness. Adapted microstructures of uncoated carbon fiber preforms were developed to permit the rapid infiltration of molten alloys and the subsequent reaction with the carbon matrix. Furthermore, any direct reaction between the melt and fibers was minimized. Using pure silicon as the reactive melt, C/SiC composites were manufactured with an aim of employing the resulting composite for friction applications. This paper describes the formation of the microstructure inside the C/C preform and resulting C/C-SiC composite, in addition to the MAX phases.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.475-478
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• 2005

Permalloys were successfully fabricated by melt drag casting in the present study, and their variation of microstructure and consequent magnetic properties were investigated as a function of Si contents and annealing temperature. The increases in Si content and annealing temperature resulted in the increases of grain size and amount of $Ni_3Fe$ ordered phase. Both the grain size and $Ni_3Fe$ ordered phase controlled by Si and annealing temperature had a important role on permeability of permalloys.