Growth rate effects during indium-antimony crystal growth

Local interface velocities are tracked radioscopically in the III-V semicon ductor compound indium-antimony grown in a vertical Bridgman-Stockbarger fu rnace. Comparisons are made of interface velocities from five different com positions (40, 49, 50, 55, and 60 at.% Sb). Under specific growth condition s, the growth velocity for stoichiometric melts was comparatively constant and very close to the translation velocity. Measured chemical homogeneity w as excellent, though polycrystallinity could occur when concentration bound ary layers formed ahead of the interface. Off-stoichiometric melts exhibite d initial supercooling, resulting in transient interface velocities and pol ycrystallinity. The observed supercooling is governed by chemical segregati on in the melt. Thus, local growth velocity fluctuations are unambiguously attributed to a coupling of compositional effects in the melt and crystal f acetting kinetics.