KINETIC SELF-STABILIZATION OF A STEPPED INTERFACE - GROWTH INTO A SUPERCOOLED MELT

We investigate the effect of anisotropic kinetics on the morphological stability of a pure material growing at constant velocity into a supercooled melt. The kinetic anisotropy is based on the motion of elementary seeps and the stability of a planar interface with respect to the formation of macrosteps or step bunching is considered. Kinetic anisotropy and capillarity stabilize the interface, while the temperature gradient in the melt is destabilizing. Linear stability calculations for dislocation and nucleation controlled growth of salol indicate that anisotropic kinetics provides stabilization for sufficiently low growth velocities for crystals of practical dimensions. Although the critical crystal size depends on the growth velocity, for materials like salol, instability may occur for dimensions larger than tens of centimeters, while for materials like germanium the critical size is less than a centimeter.