利用焓-多孔介质法对垂直Bridgman生长CdTe的数值模拟

利用数值模拟研究了碲化镉在垂直Bridgman炉中生长时的固-液界面的形状．采用焓-多孔介质法，在固定网格上对碲化镉的固液两相用统一的控制方程进行了整场求解，用一特征参数确定界面的位置和形状．结果表明，当晶体的生长速率较低时，界面的形状与物质在固态和液态两相下的热扩散率有关．如果两种热扩散率的数值相近，界面的形状是平坦的．液态区自然对流是界面形状的影响因素之一，而积聚在固态区的结晶潜热是形成弯曲固-液界面的主要原因．

Numerical simulation of CdTe vertical Bridgman growth using enthalpy-porosity technique

A CdTe crystal vertical Bridgman system is introduced, and its heat and momentum transport are analyzed by means of numerical simulation. An enthalpy-porosity formulation based fixed grid methodology incorporated into a pressure-based algorithm is employed to determine the position and shape of the melt/crystal interface. A single set of conservation equations and boundary conditions are used for the whole domain comprising the solid and liquid phases. This approach avoids the need to determine the interface explicitly, but defines a suitable characteristic parameter to describe the interfacial conditions. The results have shown that the melt/crystal interface shape is related to the thermal diffusivities of CdTe, and the similar thermal diffusivities between the melt and solid CdTe give rise to flat interface at lower growth rate. Natural convection in melt CdTe has influence on the interface shape, while it is the main reason for a concave shape that poor thermal conductivity of solid CdTe restrains the great amount of latent heat of solidification from being conducted away.