CZ法砷化镓单晶生长中熔体流动状态转换

Flow Transitions in Melts during Czochralski Growth of GaAs Single Crystal

考虑浮力、热毛细力、离心力和科里奥利力的情况下,对CZ法砷化镓单晶生长中熔体流动和传热建立了三维时相关紊流数学模型．通过数值求解预测到了熔体中流动状态的转变．结果表明,熔体中温度梯度驱动的浮力与热毛细力的联合作用和晶体旋转产生的离心力与科里奥利力的联合作用相匹配时,熔体流动为非轴对称流动;当其中一方占优势时,熔体流动为轴对称流动．流动为非轴对称流动时,熔体中出现斜压热流体波．由轴对称流动转变为非轴对称流动的机制为斜压不稳定性．得到了能描述不同条件下熔体流动状态的流动区域图．数值结果对优质砷化镓单晶生长具有重要的参考价值．

The time-dependent and three-dimensional turbulent mathematics model is established for the flow and heat transfer of GaAs melt in the Czochralski system. The flow transitions in the melts are predicted. When the combined buoyancy and Marangoni forces induced by temperature gradient are comparable to the combined centrifugal and coriolis forces induced by crystal rotation, the flow in the melt is non-axisymmetric, and when either of them is dominant, the flow is axisymmetric. Baroclinic thermal wave is observed in the non-axisymmetric flow. The mechanism of to non-axisymmetric flow is the baroclinic instability. The flow regime diagrams classifying the flow mode under different conditions are obtained. The calculated results can be taken as a reference for growth of GaAs single-crystal with high quality.