| Summary: | 碩士 === 國立成功大學 === 工程科學系碩博士班 === 91 === The crystal growth of GaAs includes the coupling of temperature, flow and concentration fields, the releases latent heat, the shape variation of solid/liquid interface, and the solute redistribution. In this complicated problem of crystal growth, the solute segregation attracts great attention. In this paper, an axi-symmetric model was built to simulate the crystal growth of GaAs in a Bridgman furnace. The SIMPLE algorithm was used to solve the flow field and the specific heat/enthalpy method was applied to handle the latent heat. A special control-volume treatment of concentration field at the solid/liquid interface was utilized to formulate the solute release there. The proposed model was used to investigate the relationship among the flow and temperature fields, the shape of solid/liquid interface, and the solute redistribution under different working conditions (different thermal boundary conditions, Rayleigh numbers, and Stefan numbers). From the computing results, by the latent heat and ks ¹ kL, the radiant temperature gradients were induced, which lead to the curved solid/liquid interface. And the natural convection is caused by the curved interface. The natural convection has a great effect on the solute redistributions, but not on the temperature fields. Modifying the temperature distribution along the furnace wall could make the solid/liquid interface flatter (less curved), which could improve the condition of solute segregation in either radial or axial direction.
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