底部保温结构对大尺寸蓝宝石晶体生长影响的数值模拟及实验研究

Simulation and Experimental Research on the Effect of Bottom Shield Structure on the Large-size Sapphire Crystal Growth

底部保温结构决定了坩埚底部径向温差的大小,底部径向温差的大小决定了晶体收尾生长的形态,合适的底部径向温差可以保证良好的晶体收尾生长,抑制界面翻转。利用CFD软件模拟底部保温结构对长晶功率、坩埚底部径向温差及界面凸出度的影响。结果表明,利用分体式底部保温结构,在扩肩及收尾阶段均可以获得最小的长晶功率、最大的底部径向温差、最大的晶体界面凸出度。依据优化的结果,采用分体式底部保温结构进行长晶实验,生长出的晶体底部表面呈现年轮状,晶体品质良好。

The radial temperature difference at the bottom of crucible is determined by the bottom shield structure.The morphology of crystal tailing growth is determined by the radial temperature difference at the bottom of crucible.The suitable radial temperature difference at the bottom of crucible can ensure good crystal tail growth and inhibit interface inversion.CFD software was used to simulate the effects of different bottom shield structure on the crystal power,the radial temperature difference at the bottom of crucible and the convexity.The results show that the smallest crystal power,the largest radial temperature difference at the bottom and the largest convexity can be obtained by using the splitting bottom shield structure whenever the shouldering and the tailing stage.According to the optimized results,the splitting bottom shield structure was used to carry out the experiment of crystal growth.The bottom surface of the crystal showed annual rings and the crystal quality was good.