Mathematical Modelling and Computer Simulation of Crystal Growth from LiquidPhase under Microgravity Conditions, Phase 2

摘要

A two-dimensional model based on fluid flow and mass transport was used tosimulate dissolution and liquid phase epitaxial growth of Si from an In solution in a sandwich system. The results are found to be in very good qualitative and quantitative agreement with experiments. In particular, the observed differences between upper and lower substrate thicknesses are correctly predicted for both dissolution and growth processes. This phenomenon is explained in terms of the predominance of convection in the lower part of the sandwich cell, in the case of dissolution, and in the upper part, in the case of growth. In both processes, a smooth substrate surface was obtained in the diffusion dominated region, and this behavior has been confirmed in experiments. The effects of gravity on dissolution depths were also tested in simulations. For liquid phase electroepitaxy (LPEE) growth of GaAs, the first step in the modelling which is concerned with the two-dimensional thermal analysis of the growth furnace, has been completed. The model is based on heat transport considerations. A new definition of the temperature change at the solution substrate interface has been devised which clearly characterizes the contribution of the Peltier effect in the process.