STR Group

Saint Petersburg, Russia

STR Group

Saint Petersburg, Russia
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Su W.,Jiangsu University | Zuo R.,Jiangsu University | Mazaev K.,STR Group | Kalaev V.,STR Group
Journal of Crystal Growth | Year: 2010

In solar-grade single crystal silicon Cz growth, the geometries of argon flow guide, heat shields and insulations are main parameters affecting the heat exchange and crystal growth conditions. By changing the above parameters, an optimization of crystal growth was attempted. Numerical simulations before and after optimization were provided to verify the results. Through analyses of the temperature distribution in the crystal and melt, the argon gas flow between the radiation shield and the quartz crucible, and the thermal stresses in the crystal, it was found that the optimized heat shield can reduce the baking of crystal by the heater; the optimized side insulation can prevent the heat loss upward, and the optimized flow guide can decrease the SiO deposition on the upper wall. After optimization, under the same heater power, the crystallization rate is increased over 35%, without increase in macro-dislocation probability; the optimized V/G ratios along crystal radius are greater than the critical value, thus the probability of occurrence of OSF-ring in the crystal is also reduced. © 2009 Elsevier B.V. All rights reserved.


Wang C.-Y.,Jiangsu University | Zuo R.,Jiangsu University | Smirnov A.,STR Group | Mazaev K.,STR Group
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2011

In sapphire crystal growth by Kyropoulos method, the thermal fields of the furnace have great influence on the crystal quality. By changing the radiation shield shape, heater position and thickness of the wall insulation, an optimization of the heat field was attempted. Through the numerical simulation of the thermal fields before and after optimization, the axial and radial temperature gradients, heater power and temperature distribution along the crystal surface were obtained. The axial heat transfer in the furnace was improved after the radiation shield was tilled, which played a role of after-heater, thus the thermal stress in the crystal was reduced. The thermal resistance between heater and crucible, and the Mo insulation in the bottom furnace were also reduced. After the optimization the energy savings of about 8% is obtained.


Su W.-J.,Jiangsu University | Zuo R.,Jiangsu University | Kalaev V.,STR Group
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2010

In solar-grade single crystal growth with CZ method, the geometries of flow guide, radiation shield and side wall insulation are main parameters affecting the heat fields and crystal growth. By changing the above parameters, an optimization of the heat fields was attempted. Numerical simulations of the thermal fields before and after optimization were conducted. Through analysis of the temperature distribution in the crystal and melt, the argon gas flow between radiation shield and quartz crucible, and the thermal stress in the crystal, it was found that the optimized flow guide can decrease the SiO deposition on the upper wall; the optimized radiation shield can reduce the baking of crystal by the heater; and the optimized side insulation can prevent the heat loss upward. In general, after optimization, under the same heater power, the crystallization rate increases over 35%, without increase of macro-dislocation probability.

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