Analysis of GaAs Crystal Growth by Using Modified Effective Specific Heat Method and Interfacial Extra Node Scheme with Modified Furnace Wall Temperature

• Main Authors: Yau-chia Liu, 劉曜嘉
• Other Authors: Long-sun Chao
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/47813151091108218521

博士 === 國立成功大學 === 工程科學系碩博士班 === 95 === This work is to develop a new mathematical model to simulate the crystal growth in a Bridgman furnace. The relationship among the flow, temperature, concentration fields, the released latent heat and the curved solid/liquid interface was investigated. In this paper, the numerical scheme is the finite different method. The SIMPLEC algorithm is used to solve the flow field. The effective specific heat method is modified to handle the release of latent heat. Adding extra nodes at the interface is proposed to deal with the solute release at the solid/liquid interface. The computational results of these two new methods are compared with those of other methods and very consistent with the exact solutions from the literature. From the analysis of the crystal growth, it can be found that the curved solid/liquid interface is caused by the unequality of liquid and solid thermal conductivities and the latent heat. The curved interface induces the natural convection, which has a great effect on the solute redistribution, but not on the temperature field. To ease off the effect of curved interface, a modified temperature profile of furnace wall was applied according to the heat balance at the solid/liquid interface and its results have less curved interfaces, weaker flow fields and lower segregations along either the radial or the axial direction than those of unmodified one. With the modified method, it could be expected to have the better crystal quality, having more uniform distribution of dopant.