• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.4
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• pp.135-138
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• 2016

It was observed that the single grain of crystallite growth behavior in AlN (Aluminum Nitride) single crystal growth by PVT (Physical Vapor Transport) method. The single grain of AlN was grown in sequent experiments and adjacent crystallites were joined together after small grain was grown. The sequential results of those grains observed by stereoscopic microscope were reported.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.1
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• pp.72-79
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• 1998

Journal of the Korean Society of Clothing and Textiles Vol. 22, No. 1 (1998) p. 72∼79 The purpose of this study was to investigate the effects of geometrical structure and fiber type on the water vapor transport properties of nonwoven batting materials. Two types of fiber were used such as polyester and wool. Correlation between physical properties of nonwovens and water vapor transport rate was analyzed by Pearson Correlation. Steady and dynamic state water vapor transport properties were measured by absorption, evaporation and cobaltots chloride method respectively. The results were as follows: 1) In geometrical structure, thickness of nonwovens was effected on absorption and evaporation rate and air permeability was more influencing factor on water vapor transport rate than porosity. There were no decreasing of water vapor transport rate in hydrophilic fiber at high relative humudity. 2) The hydrophilicity of fiber affected steady and dynamic state water vapor permeabilities and wool nonwoven showed higher water vapor transport rate than polyester at high relative humidity. 3) Thickness showed higher correlation coefficient with water vapor transport rate than other physical properties of nonwovens.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.4
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• pp.187-198
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• 2003

Zinc selenide (ZnSe) single crystals hold promise for many electro-optics, acousto-optic and green laser generation applications. This material is prepared in closed ampoules by the physical vapor transport (PVT) growth method based on the dissociative sublimation. We investigate the effects of diffusive-convection on the crystal growth rate of ZnSe with a low vapor pressure system in a horizontal configuration. Our results show that for the ratios of partial pressures, s=0.2 and 2.9, the growth rate increases with the Peclet number and the temperature differences between the source and crystal. As the ratio of partial pressures approaches the stoichiometric value of 2, the rate increases. The mass fluk based on one dimensional (1D model) flow for low vapor pressure system fall within the range of the predictions (2D model) obtained by solving the coupled set of conservation equations, which indicates the flow fields would be advective-diffusive. Therefore, the rate and the flow fields are independent of gravity acceleration levels.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.2
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• pp.54-58
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• 2014

AlN (Aluminum Nitride) crystals were grown by a PVT (Physical Vapor Transport) method and were characterized to phases on the growth temperature. The crystals phase and morphology were analyzed using an optical stereo-microscope and the optimum temperature for the growing was determined. In this report, the characteristics of the AlN crystals grown at various temperatures were reported.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.3
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• pp.140-142
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• 2019

AlN (Aluminum Nitride) crystal which could be used to substrates for UV LEDs was grown by PVT ((Physical Vapor Transport) method. 3 inch AlN single crystal with a thickenss of 4 mm was grown using Polycrystalline seed for 120 hours. In this report, a result of 3 inch polycrystalline bulk AlN growth behavior using large size crucible and growth condition were reported.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.1
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• pp.49-52
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• 2016

The effect of process parameters such as the growth pressure and temperature on the AlN crystal growth has been investigated. AlN crystal was grown onto 6H-SiC seed crystal using PVT (Physical Vapor Transport) method. Crystal properties and morphology of AlN crystal was changed with growth pressure and temperature. Raman analysis confirmed that AlN crystals with different orientation were successfully grown on SiC seed crystal.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.39-43
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• 1997

Mercurous chloride (Hg$_2$Cl$_2$) has many advantages in its applications to acousto-optic, and opto-electronic devices because it has the unique properties of a broad transmisson range, well into the far infra-red, a low acoustic velocity, a large birefringence, and a high acousto-optic figure of merit[1]. Hg$_2$Cl$_2$ has a high vapor pressure, hence single crystals are usually grown by physical vapor transport(PVT) method in closed silica glass ampoules. We discuss the application of the laser Doppler velocimetry to measure the flow field inside a closed ampoule. The experimental results, are discussed its relationship to computational model and compared to their expectations.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.4
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• pp.148-151
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• 2018

A large single crystal of AlN was grown by PVT (Physical Vapor Transport) method. The AlN crystal shaped hexagonal of the diameter of about 46 mm and the thickness of 7.6 mm was grown using 33 mm seed crystal which was grown and made by ourselves. We tried to find out repeatable growth possibility for AlN crystal growth and then to evaluate the repeatability of the growth condition of the temperature of $1950{\sim}2100^{\circ}C$ and the ambient pressure of 0.1~1 atm.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.5
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• pp.163-167
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• 2020

Ring-shaped SiC (Silicon carbide) polycrystals used as an inner material in semiconductor etching equipment was manufactured using the PVT (Physical Vapor Transport) method. A graphite cylinder structure was placed inside the graphite crucible to grow a ring-shaped SiC polycrystal by the PVT method. The crystal polytype of grown crystal were analyzed using a Raman and an UVF (Ultra Violet Fluorescence) analysis. And the microstructure and components of SiC crystal were identified by a SEM (Scanning Electron Microscope) and EDS (Energy Disruptive Spectroscopy) analyses. The grain size and growth rate of SiC polycrystals fabricated by this method was varied with temperature variation in the initial stage of growth process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.272-282
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• 2002

Mercurous bromide ($Hg_{2}0Br_{2}$) crystals hold promise for many acousto-optic and opto-electronic applications. This material is prepared in closed ampoules by the physical vapor transport (PVT) growth method. Due to the temperature gradient between the source and the growing crystal region, the buoyancy-driven convection may occur. The effects of thermal convection on the crystal growth rate was investigated in this study in a horizontal configuration for conditions ranging from typical laboratory conditions to conditions achievable only in a low gravity environment. The results showed that the growth rate increases linearly with Grashof number, and for 0.2 $\leq$ Ar (transport length-to-height, L/H)$\leq$1.0 sharply for Ar=5 and $\Delta$T=30 K. We have also shown that the magnitude of convection decreases with the Ar. For gravity levels of less than $10^{-2}$g the non-uniformity of interfacial distribution is negligible.