Electromagnetic control of convection in semiconductor melts: thermoelectromagnetic convection (TEMC) and rotating magnetic fields

Abstract

Application of a low intensity axial magnetic field can promote significant convection during Bridgman growth of GeSi when resident thermoelectric currents at the growth interface are large due o difference of thermoelectric powers of the melt and of the crystal and the tangential temperature gradient at the interface. Thermoelectromagnetic convection (TEMC) in the GeSi melt is characterized by a meridional flow driven by the rotation of the fluid due to the azimuthal Lorentz force from currents in the radial direction, concentrated near the interface, and the axial magnetic field. A similar flow is caused by a rotating magnetic field (RMF). When the field is rotating sufficiently fast, a time-averaging azimuthal Lorentz force (almost uniform axially) causes a steady rotation of the melt, and an associated meridional convection (Ekman cells) near the interface. In this work, we developed a computational model to study convection of the GeSi melt in a microgravity environment in the presence of low intensity magnetic fields.