• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.2
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• pp.45-50
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• 2005

During oxidation process, several type of defects are formed on the surface of the silicon crystal which was damaged mechanically before oxidation. As the size of abrasive particle increases multiple dislocation loops are produced favorably over oxidation-induced stacking faults, which are dominantly produced when ground with finer abrasive particle. These defects are not related with the crystal growth process like Czochralski or directional solidification. During directional solidification process, twins and stacking faults are the two major defects observed in the bulk of the silicon crystal. On the other hand, slip dislocations produced by the thermal stress are not observed. Thus, not only in single crystalline silicon crystal but also in multi-crystalline silicon, extrinsic gettering process with programmed production of surface defects might be highly applicable to silicon wafers for purification.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.168-172
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• 1999

The 9 $\mu\textrm{m}$ GaN films on sapphire substrate were grown by Hydride vapor phase epitaxy. Dislocation density of these GaN films was measured by TEM. GaN film with crack free and mirror surface was directly grown on sapphire substrate. The dislocation density of this GaN film was $2{\times}10^9/cm^2$. The surface of GaN film on patterned GaN layer also presented a smooth mirror. But a part of GaN surface included holes because of incomplete coalescence. The dislocation density of GaN film above the mask region was lower than that in the window region. Especially, the dislocation density in the region between mask center and window region was close to dislocation free. The average dislocation density of ELO GaN was $8{\times}10^7/cm^2$.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.5
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• pp.239-244
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• 2021

Following Silicon Carbide, single crystal diamond continues to attract attention as a next-generation semiconductor substrate material. In addition to excellent physical properties, large area and productivity are very important for semiconductor substrate materials. Research on the increase in area and productivity of single crystal diamonds has been carried out using various devices such as HPHT (High Pressure High Temperature) and MPECVD (Microwave Plasma Enhanced Chemical Vapor Deposition). We hit the limits of growth rate and internal defects. However, HFCVD (Hot Filament Chemical Vapor Deposition) can be replaced due to the previous problem. In this study, HFCVD confirmed the distance between the substrate and the filament, the accompanying growth rate, the surface shape, and the Raman shift of the substrate after vapor deposition according to the vapor deposition temperature change. As a result, it was confirmed that the difference in the growth rate of the single crystal substrate due to the change in the vapor deposition temperature was gained up to 5 times, and that as the vapor deposition temperature increased, a large amount of polycrystalline diamond tended to be generated on the surface.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.2
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• pp.75-80
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• 2021

The crystal grains of polycrystalline diamond vary depending on deposition conditions and growth thickness. The diamond thin film deposited by the CVD method has a very rough growth surface. On average, the surface roughness of a diamond thin film deposited by CVD is in the range of 1-100 um. However, the high surface roughness of diamond is unsuitable for application in industrial applications, so the surface roughness must be lowered. As the surface roughness decreases, the scattering of incident light is reduced, the heat conduction is improved, the mechanical surface friction coefficient can be lowered, and the transmittance can also be improved. In addition, diamond-coated cutting tools have the advantage of enabling ultra-precise machining. In this study, the surface roughness of diamond was improved by thermal diffusion reaction between diamond carbon atoms and ferrous metals at high temperature for diamond thin films deposited by MPCVD.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.1
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• pp.1-4
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• 2003

In the present work we consider morphological structure of the faces of BGO crystals grown by Czochralski technique under the conditions of low temperature gradient (0.1~1 deg/cm) and interconnection between the morphological features of faces at the crystallization front and the formation of defects within the crystal volume. It is demonstrated that the {112} faces retain stability while the growing surface deviates from the crystallographic (112) plane up to 1 degree. At larger deviation, the region of the stable facet growth passes either to the region of macrosteps or to the region of normal growth. depending on conditions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.2
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• pp.68-71
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• 2008

AlN crystals were grown by the sublimation process. As grown AlN crystals were the polycrystalline boule in the form of the agglomerate of small AlN single crystalline AlN. As-grown AlN boule has a length about 2${\sim}$3 mm long and a diameter of 1 inch. The carbon impurities were observed on the surface and inside of the grown AlN crystals and the growth behavior was investigated by optical microscopy and SEM observation.

• Journal of the Korean Ceramic Society
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• v.29 no.3
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• pp.189-194
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• 1992

In order to grow a 127.86$^{\circ}$rotated LiNbO3 single crystal with good characteristics of surface acoustic wave (SAW) up to 80 mm in diameter, the temperature gradient of furnace, the growth rate and the rotation rate of crystal were changed. We could grow a crystal which had few macro defects at the conditions of temperature gradient as 30~6$0^{\circ}C$/cm, growth rate as 5 mm/hr and rotation rate as 8 rpm. The experimental ranges of the growth conditions are as follows. Temperature gradient was varied from 20 to 20$0^{\circ}C$/cm, growth rate as 5~7 mm/hr and crystal rotation rate as 6~12rpm.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.337-350
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• 1999

Thick diamond film having ~700${\mu}{\textrm}{m}$ thickness was deposited on polycrystalline molybdenum (Mo) substrate using high power (4kW) microwave plasma enhanced chemical vapor deposition (MPECVD) system. We could achieve free-standing diamond film via detaching as-deposited diamond film from the substrate by rapid cooling them under vacuum. We investigated the variation of photoconductivity after exposing the film surface to either oxygen or hydrogen plasma. At as-grown state, the growth side (the as-grown surface of the film) showed noticeable photoconductivity. The oxygen plasma treatment of this side led to the insulator. After exposing the film surface to hydrogen plasma, on the other hand, we could observe the reappearing of photoconductivity at the growth side. Based on these results, we suggest that the hydrogen plasma treatment may enhance the photoconductivity of free-standing diamond film.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.351-360
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• 1999

A large NaX type zeolite crystal of a uniform particle size of 20${\mu}{\textrm}{m}$ are grown with various H2O content by hydrothermal reaction and added seed crystal (2~3 ${\mu}{\textrm}{m}$) to reactant solution as a function of different adding seed levels from 3 to 15 %. The result that increased purity of NaX zeolite above 95% and homogeneity of crystal size by increasing adding seed levels, also decreased crystallization time. It was explained that adding seed to synthesis solution leaded out increase of surface area of physical contact reaction and directed growth of seed crystal, so more rapid consumption of reaction gel as increase seeding levels.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.5
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• pp.198-202
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• 2006

We could achieve the bridge-type formation of the iridium-catalyzed carbon nanofibers across the gap on the MgO substrate using microwave plasma enhanced chemical vapor deposition method. On the plane surface area of the MgO substrate, the iridium-catalyzed carbon nanofibers were grown as a lateral direction to the substrate. The bridge-type formation and/or the lateral growth of the iridium-catalyzed carbon nanofibers were interconnected with each other. Finally, they could form an entangled network having the bridge-type formation of the carbon nanofibers across the gap on the substrate and the laterally-grown carbon nanofibers on the plane surface area of the substrate. The entangled network showed the semiconductor electrical characteristics.