| Summary: | 碩士 === 國立成功大學 === 工程科學系 === 88 === Abstract
The process of crystal growth of GaAs is a complex problem. The problem includes the heat transfer in melt, crystal and ampoule, the natural convection induced by radial temperature gradient, and solidification. The finite difference method and staggered grid were used for the transient analysis. The flow field was solved by using the SIMPLEST algorithm, and the effective specific heat method was applied to handle the solidification problem. In this paper, we studied the relationship among the temperature field, the flow field and the shape of melt/crystal interface under different boundary conditions. From the computing results, it was found that (1) the latent heat released during solidification leads to the radial temperature gradient near the solid-liquid interface, (2) the radial temperature gradient results in the natural convection and the deflection of the interface. According to the heat balance at the solid-liquid interface, we adjust the furnace temperature gradients (corresponding to the solid and liquid portions) so that the less curved interface and the smaller intensity of natural convection can be obtained. This is expected that in this working condition the better crystal quality (more uniform dopant distribution) can be obtained.
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