• Korean Journal of Crystallography
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• v.11 no.4
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• pp.207-211
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• 2000

In a Czochralski silicon single crystal, the relation between the growth twin and the crystal morphology was investigated. The growth twin is nucleated on the {111} facet planes near the growth ridges. When a {111} growth twin is formed in the <100> silicon crystal, the growth ridge where twin is nucleated will continuous through the twin plane. Other two ridges at the 90。 apart will be displaced about 33° and be deformed to facets. The ridge on the opposite side of twin nucleation will disappear by forming a slight hill. Because the growth ridges of silicon is due to the {111} planes, the variation in the growth ridge formation can be predicted clearly by considering the change of the {111} plane traces in the stereographic projection after twining.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.4 no.1
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• pp.121-131
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• 2000

Melt flow, heat and mass transfer of oxygen have been analyzed numerically in the process of Czochralski single crystal growth of silicon under the influence of misaligned cusp magnetic fields. Since the silicon melt in a crucible for crystal growth is of high temperature and of highly electrical-conducting, experimentation method has difficulty in analyzing the behavior of the melt flow. A set of simultaneous nonlinear equations including Navier-Stokes and Maxwell equations has been used for the modelling of the melt flow which can be regarded as a liquid metal. Together with the melt flow which forms the Marangoni convection, a flow circulation is observed near the comer close both to the crucible wall and the free surface. The melt flow tends to follow the magnetic lines instead of traversing the lines. These flow characteristics helps the flow circulation exist. Mass transfer characteristics influenced by the melt flow has been analyzed and the oxygen absorption rate to the crystal has been calculated and turned out to be rather uniform than in the case of an aligned magnetic field.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.1
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• pp.1-11
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• 1993

A suppression of turbulent fluid motion and a control of oxygen and dopants could be improved by application of magnetic field in Czochralski growth of silicon. The effect of an axial magnetic field on Czochralski system was numerically calculated. The fluid motions induced by temperature gradients and by crystal and crucible rotations were suppressed by magnetic force. The S/L interface was gradually flattened in proportion to the increase of magnetic field due to a reduced ascending velocity in the vicinity of center line. The t.emperature distributions in the melt at 8=0.3 Tesla were similar to those analyzed by the conduction heat transfer only. The dissipated amounts of heat flux from melt and crystal surfaces by Ar gas blowing was Jess than 3 %.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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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.

• International Journal of Control, Automation, and Systems
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• v.3 no.2
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• pp.252-257
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• 2005

In this work, we propose a simple but efficient method to design a target temperature trajectory for pulling speed tracking control of the crystal grower in the Czochralski crystallization process. In the suggested method, the model predictive control strategy is used to incorporate the complex dynamic effect of the heater temperature on the pulling speed into the temperature trajectory design quantitatively. The feedforward trajectories designed by the proposed method were implemented on 200 mm and 300 mm silicon crystal growers in the commercial Czochralski process. The application results have demonstrated its excellent and consistent tracking performance of pulling speed along whole bulk crystal growth.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.5
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• pp.222-229
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• 2003

InP crystal is an increasingly important semiconductor material in the application of long-wave optoelectronic and high frequency devices. The equilibrium vapor pressure of phosphorus at the melting point of InP is so high that the synthesis process is very difficult. Liquid-encapsulated Czochralski (LEC) pulling from the melt at high pressure is a generally favored technique to grow InP single crystals. This technique involves two steps: the synthesis of polycrystalline powder and the growth of single crystal from the melt at high pressure. This article reviewed the latest development in the preparation of InP crystal and the evaluation on the crystal quality.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.555-562
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• 1998

Under the influence of non-uniform magnetic field, melt flow in steady state and oxygen concentration in unsteady state are numerically investigated. The strength of the applied characteristic magnetic fields are B=0.1T, 0.2T, and 0.3T, respectively. The buoyancy effects due to the crucible wall heating and the thermocapillary effects due to the surface tention at the free surface are suppressed differentially by the non-uniform magnetic fields. As the intensity of characteristic magnetic fields is increasing, the recirculation region in the meridional plane is moving toward the growing crystal, and is diminishing. The oxygen concentration on the growing surface of crystals is decreasing and the uniformity of the oxygen concentration is increasing as the intensity of the magnetic fields is increasing.

• 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 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.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.3
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• pp.388-397
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• 1999

Numerical simulations are carried out for the magnetic Czochralski single crystal growth system. It Is shown that a magnetic field significantly suppresses the convective flow and as the strength of magnetic field becomes to be stronger, the heat transfer in the melt is dominated by conduction rather than convection. By imposing a cusp magnetic field, the growth interface shape becomes convex toward the melt. When the axial magnetic field is imposed, there occurs an inversion of the interface shape with increase of the magnetic field strength. The oxygen concentration near the interface decreases with increasing cusp magnetic field strength while axial field causes an increase of an oxygen concentration at the central region and decrease of that at the edge of the crystal. The results show that the cusp magnetic field has advantages over an axial magnetic field In the radial uniformity of oxygen as well as in the additional degree of control.