Three-dimensional modeling of Ge₁₋xSix by the traveling solvent method to study the effect of gravity orientations under different rotational speed

Abstract

This thesis presents a 3-D numerical simulation study for the growth of germanium-silicon (Ge₁₋xSix) under different gravity orientation and axial rotation. The process use for crystal growth of Ge₁₋xSix is traveling solvent method known as TSM. The TSM process has been tested on many alloys producing uniform and uncontaminated crystal products. In this model a mesh sensitivity analysis his been carried out to find an optimum mesh which provides accurate results while saving computational time. The full Navier-Stokes equations together with the energy, mass transport and continuity equations were solved numerically using the finite element technique. The application of gravity orientation and crucible rotation to the traveling solvent method is an attempt to control the buoyancy induced convection throughout the melt and to suppress the three-dimensional characteristics of unsteady heat flow. These different speeds of rotation were shown to have a considerable effect on the buoyancy induced flow. The solute distribution throughout the melt was also affected substantially. Taking these two factors into account plays a crucial role in the crystal growth process. The speed of rotation showed to have a significant effect on the intensity of the convective flow in the melt and an optimal rotational speed was encountered.