Navier-Stokes modelling of coupled interfacial and convective transport during the Ge epitaxial growth experiments of D1 mission

Abstract

The 2-D Navier-Stokes species and energy conservation equations are solved to model the transport process during Ge crystal growth in GeI 2/Gel 4 system in closed cell. The coupling between convection and interface transport is taken into account through mixed type boundary conditions in which the net production term is deduced from the surface kinetics involving a limiting step of GeI 2 adsorption. It is found that: (a) for the real flight deposit temperature, the substrate evaporates as observed in the D1 experiment (15); (b) for the planned deposit temperature, the model shows a very light evaporation of the substrate; (c) for 3 K beneath the planned temperature, a deposit occurs on the substrate; and (d) the velocity on the substrate (deposition or evaporation) for similar thermal conditions depends on the gravity level. This numerical model, in which hydrodynamics and surface physics are really coupled, seems to be a good investigation tool.