Bridgman-Stockbarger Growth of Binary Alloyed Semiconductor Crystals with Steady Magnetic Fields

摘要

Single crystals of alloyed compound semiconductor crystals such as gallium-aluminum-antimonide are needed for optoelectronic devices. These crystals are solidified from a solution of molten gallium-antimonide and aluminum-antimonide in a Bridgman-Stockbarger furnace. During the growth of alloyed semiconductor crystals, the solute's concentration is not small so that the density differences in the melt are very large. These compositional variations drive compositionally driven buoyant convection, or solutal convection, in addition to thermally driven buoyant convection. These buoyant convections drive convective species transport, which produce nonuniformities in the concentration in both the melt and the crystal. A numerical model is presented for the unsteady transport for the growth of alloyed semiconductor crystals during the vertical Bridgman-Stockbarger process with a steady axial magnetic field. Predictions of alloy concentration in the crystal and in the melt at several different stages during crystal growth are presented.