Morphological variations of graphite strip heater recrystallized silicon‐on‐insulator formed in the initial stage of seeded growth have been analyzed to examine the thermal gradient effect upon the growth stability. Systematic transition of the stable growth into an orderly breakdown of faceted, cellular, and dendritic configurations has been attributed to the decreasing temperature gradient in this region. There are indications that constitutional supercooling could be responsible for the interface stability breakdown and that increased thermal gradients can suppress the onset of breakdown and maintain the stable growth over an extended distance.