砷化鎵於單晶成長的過程中，包含了溫度場、流場、濃度場的互相耦合、液固相變化時的潛熱釋放效應、液固界面的形狀變化、長晶時的濃度再分佈等，是一個很複雜的問題，其中濃度場中的溶質偏析現象，特別受到關注。
本文藉由軸對稱的模式來模擬砷化鎵在布氏爐中的長晶過程。在數值方法上在採用SIMPLE演算法來求解速度場，再以等效比熱-熱焓法來處理凝固相變化時潛熱釋放的問題，並使用特殊增加格點的方式去處理濃度場在液固界面的效應。本文使用上述方法來探討砷化鎵在不同工作條件(潛熱、雷利數)下，溫度場、液固界面形狀、流場變化及濃度再分佈間的相互關係。
從結果中發現，由於液、固態熱傳導係數的差異造成徑向的溫度梯度，而使得液固界面產生撓曲，進而產生自然對流。而自然對流對於溶質在分佈具有強烈的主導性。當考慮潛熱釋放效應後，會使俓向溫度梯度加大，形成更撓曲的液固界面的形狀及更強的流場分佈，本文藉由調整爐壁溫度分佈，得到較平坦的液固界面，進而提昇界面之溶質分佈均勻度，來改善長晶之偏析現象。

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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