[en] The recrystallization behavior during annealing of thin films of amorphous (α) silicon, in contact with a single crystal silicon substrate (referred to as C), has been studied in the transmission electron microscope (TEM). The amorphous film is created during high dose phosphorus ion implantation at 100 keV. It was found that the crystal substrate orientation and the implantation temperature have dramatic effects on the recrystallizaton rate, and the defect microstructure produced during annealing. Specifically, (100) wafers implanted at 77⁰K contain only a low density of dislocation loops, but when the same wafer is implanted at room temperature the dislocation density is increased drastically. (111) wafers, when implanted at 77⁰K show a high density of microtwins, but as the implantation temperature is increased a gradual increase in the density of dislocation loops is observed along with a reduction of the microtwins. At an implantation temperature of about 100⁰C both orientations give an identical defect microstructure when annealed, which is a dense tangle of dislocations