• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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• pp.74-81
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• 1991

The temperature profile of Czochralski single crystal growth system was simulated considering the fluid flow and surface radiation heat transfer. View factors of surface elements were calculated for radiation heat transfer. Two phases(solid and liquid) were treated as a continuous phase by assigning artificial large viscosity to the solid phase and latent heat was accounted by iterative heat revolution method. The solidification model was applied to solid front of the pure Ga during the melting to verify the model. The whole simulation model of CZ system was applied to the growth Al single crystal.

• Korean Journal of Crystallography
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• v.7 no.1
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• pp.1-7
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• 1996

We developed an automatic diameter control system to control the diameter of single crystal for Czochralski growth. The system is composed of load cell, software program and data acquisition system connected to computer which controls RF power. This study describes the basic principle, characteristics and components of the system. The diameter of Nd:YAG crystal could be controlled within ±5% tolerance by this system.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.202-206
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• 2010

Single crystals of $ZnWO_4$ were grown successfully in the [100], [010] and [001] directions using the Czochralski method. The growth parameters and the formation of slip plane in $ZnWO_4$ crystals were studied. $ZnWO_4$ crystals had a cleavage plane of (010). The dislocation density on the (010) plane at the center of the crystal was lower than that of the edge region. It was inferred that the high density at the edge of the crystals was caused by the thermal gradient during crystal growth. The etch pit arrangement revealed the (100) slip plane to be most active during crystal growth.

• Journal of the Korean Ceramic Society
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• v.27 no.5
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• pp.698-701
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• 1990

The necessary conditions for the growth of high quality Bi12SiO20 single crystals by the Czochralski method have been determined. The interface of melt and crystal was transformed convex to concave above 7 rpm. For growth <001> and <111> directions, facet morphology exhibited 4-fold and 6-fold symmetry. When the crystal of <001> growth direction was broadened, minor facet {110} was developed outstandingly.

• Analytical Science and Technology
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• v.23 no.2
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• pp.103-108
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• 2010

Single crystals of $ZnWO_4$ with [100], [010] and [001] directions were successfully grown by the Czochralski method. The seed crystals for the single crystal growth of $ZnWO_4$ could be induced by the crystal growth using platinum wires applied by the capillary action from the melt. The growth conditions in each direction were investigated in terms of the variations of rotation speed, pulling rate and diameter of the grown crystals. The formation of cracking in the grown crystals during the cooling process could be prevented by annealing effect. The growth directions of the grown crystals were determined using Laue back reflection. The microscopic characteristics of the grown crystals in each direction were discussed, and their physical properties were evaluated for hardness, thermal expansion coefficients and dielectric constants.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.4
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• pp.620-626
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• 1996

$LiNbO_{3}$ single crystals were grown using a self-designed radio-frequency heating Czochralski crystal grower. Congruently melting composition was used and the optimum growth conditions were established. The compensated power control method was very effective to control the outer diameter of the crystal ingots within ${\pm}5\;%$. Scanning electron microscopy was performed to characterize the effect of the $Mg^{2+}$ ions on the formation of the ferroelectric domain in $LiNbO_{3}$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.27-40
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• 1997

The heat in Czochralski method is transfered by all transport mechanisms such as convection, conduction and radiation and convection is caused by the temperature difference in the molden pool, the rotations of crystal or crucible and the difference of surface tension. This study delvelops the simulation model of Czochralski growth by using the finite difference method with fixed grids combined with new latent heat treatment model. The radiative heat transfer occured in the surfce of the system is treated by calculating the view factors among surface elements. The model shows that the flow is turbulent, therefore, turbulent modeling must be used to simulate the transport phenomena in the real system applied to 8" Si single crystal growth process. The effects of a cusp magnetic field imposed on the Czochralski silicon melt are studied by numerical analysis. The cusp magnetic field reduces the natural and forced convection due to the rotation of crystal and crucible very effectively. It is shown that the oxygen concentration distribution on the melt/crystal interface is sensitively controlled by the change of the magnetic field intensity. This provides an interesting way to tune the desired O concentration in the crystal during the crystal growing.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1308-1318
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• 1995

The influence of varying rotation speed of both crystal and crucible was numerically investigated for the Czochralski silicon-crystal growth. Based on a simplified model assuming flatness of free surfrae, the Navier-Stokes Boussinesq equations were employed to identify the flow pattern, temperature distribution as well as the shape of the melt/crystal interface. The present results showed that the interface shape was relatively convex with respect to the melt at lower pulling rate and tended to be concave as the pulling rate increased. In particular, the experimentally observed gull-winged shape of the interface was qualitatively in agreement with the predicted shape. The rotation of crystal alone little affected the growth system. When the rotation speed of the crucible was increased, there occurred inversion of the interface shape from convex to concave pattern. At rapid rotation of the crucible, an interesting channel formation was predictied primarily due to the assumption of laminar flow.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.4
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• pp.137-139
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• 2008

Floating zone, neutron transmutation-doped and magnetic Czochralski silicon crystals are being widely used for fabrication power devices. To improve the quality of these devices and to decrease their production cost, it is necessary to use large-diameter wafers with high and uniform resistivity. Recent developments in the crystal growth technology of Czochralski silicon have enable to produce Czochralski silicon wafers with sufficient resistivity and with well-controlled, suitable concentration of oxygen. In addition, using Czoehralski silicon for substrate materials may offer economical benefits, First, Czoehralski silicon wafers might be cheaper than standard floating zone silicon wafers, Second, Czoehralski wafers are available up to diameter of 300 mm. Thus, very large area devices could be manufactured, which would entail significant saving in the costs, In this work, the conventional Czochralski silicon crystals were grown with higher oxygen concentrations using high pure polysilicon crystals. The silicon wafers were annealed by several steps in order to obtain saturated oxygen precipitation. In those wafers high resistivity over $5,000{\Omega}$ cm is kept even after thermal donor formation annealing.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.175-180
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• 1998

Nd:YAG single crystal widely used as solid state laser was grown by Czochralski method. <111> single crystal with 0.9at% of $Nd^{3+}$ was grown from the Czochralski furnace with a automatic diameter control system. The vertical temperature gradient in the liquid was the major factor that influence the crystal quality, and the crystal diameter was controlled by the home made computer program. The crystal boule with $\phi$50mm$\times$ι100mm effective size was cut, polished, and antireflection coated. The optical evaluation such as absorption spectrum, fluorescence spectrum coincide with typical features of Nd:YAG single crystal. The laser rod was assembled into the CW laser generator with a Kr lamp. The maximum CW laser output was 70 W and the threshold power and efficiency was 1.3kW and 1.64% respectively.