LEC法GaSb晶体生长数值模拟研究

Research on Numerical Simulation for LEC-GaSb Crystal Growth

采用有限元模拟软件对液封直拉(LEC)法生长锑化镓晶体过程进行计算机建模。模拟分析了晶体旋转、坩埚旋转及隔热屏等因素对GaSb固-液界面形貌的影响。结果表明,晶体旋转与坩埚旋转分别具有促使凸向熔体的固-液界面曲率减小及增大的作用,且同等转速条件下,坩埚旋转对固-液界面形貌影响更大。此外,减小放肩角度、去除炉体上部的隔热屏等措施,均具有使凸向熔体的固-液界面曲率降低的作用。而使用液封剂使凸向熔体的固-液界面曲率增大。坩埚在加热器中存在某一位置,使熔体内部轴向梯度最大。炉膛内氩气流速最剧烈部位为保温罩与拉晶杆间的区域,Ar气对流导致上炉膛温度提高,并降低熔体表面温度约8℃。

The modelling of the LEC-GaSb crystal growth process was established by using the finite element simulation software.The influence of crystal rotation,crucible rotation,heat shield etc.on the solid-liquid interface morphology of GaSb was analyzed.The results show that the rotation of the crystal and the rotation of the crucible have the effect of increasing and decreasing the curvature of the interface,and the rotation of the crucible has a greater influence on the surface morphology under the same rotating speed condition.In addition,reducing the angle of the shoulder and removing the heat shield have a role in reducing the curvature of the solid-liquid interface;and the using of encapsulant increases the curvature of the solid-liquid interface.The crucible has a certain position in the heater,at which the axial gradient of the melt is the largest.In the furnace,the most intense flow rate of Argon gas is in the area between the pulling bar and the heat shield.Argon gas convection leads to an increase in the upper furnace temperature and the decrease of the surface temperature of the GaSb melt about 8 ℃.