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 supe rcooled melt. The kinetic anisotropy is based on the motion of element ary seeps and the stability of a planar interface with respect to the formation of macrosteps or step bunching is considered. Kinetic anisot ropy and capillarity stabilize the interface, while the temperature gr adient in the melt is destabilizing. Linear stability calculations for dislocation and nucleation controlled growth of salol indicate that a nisotropic kinetics provides stabilization for sufficiently low growth velocities for crystals of practical dimensions. Although the critica l crystal size depends on the growth velocity, for materials like salo l, instability may occur for dimensions larger than tens of centimeter s, while for materials like germanium the critical size is less than a centimeter.