Simplified numerical approach for estimation of effective segregation coefficient at the melt/crystal interface

• A thermal gravitational convection was investigated for a Bridgman technique in microgravity.
• The equations were calculated in the coordinate system moving with melt/crystal interface.
• The dependence of effective segregation coefficient Keff was studied upon microgravity and ampoule sizes.
• The resulting dependences were presented as Keff upon Vmax—maximum value of velocity magnitude.
• These dependences were compared with the data of semi-analytical and analytical models.

A thermo-gravitational convection and impurity transfer in the melt were investigated using a simplified numerical model for Bridgman GaSb(Te) crystal growth in microgravity conditions. Simplifications were as follows: flat melt/crystal interface, fixed melt sizes and only lateral ampoule heating. Calculations were carried out by Ansys®Fluent® code employing a two-dimensional Navier–Stokes–Boussinesq and heat and mass transfer equations in a coordinate system moving with the melt/crystal interface. The parametric dependence of the effective segregation coefficient Keff at the melt/crystal interface was studied for various ampoule sizes and for microgravity conditions. For the uprising one-vortex flow, the resulting dependences were presented as Keff vs. Vmax—the maximum velocity value. These dependences were compared with the formulas by Burton–Prim–Slichter׳s, Ostrogorsky–Muller׳s, as well as with the semi-analytical solutions.